To receive government funding, academic scientists submit proposals and are judged by peer-review for their science – not for either validating or negating, for example, the dangers or benefits of GMOs. Only the best of the proposals (less than 10%) are funded to do the research outlined in the proposal. There is only pressure to produce results that will be useful to the community for which the research is relevant, and that address the goals outlined in the proposal.

Academic research scientists are driven to arrive at scientific truths. This means that we don’t receive any kudos or funds for either validating or negating the issue at hand. I am only aware of one USDA program specifically aimed at examining the risks and benefits of GE crops, and the end results are not judged by which side of the fence the results end up. To bring this argument regarding academic scientists to the end point that “big business likes the concepts that they can develop a product which they can profit from” simply makes no sense in the academic world in which I and my other scientific colleagues live.

Throughout my 20 years at UC Berkeley, I have struggled to obtain funding for my outreach efforts. I have never taken money from private corporations for those efforts, and instead, receive funds from Cooperative Extension, the American Society of Plant Biologists, the National Science Foundation, and the United States Department of Agriculture’s Coordinated Agriculture Programs.

As a public sector scientist, I have no obligation to speak either for or against the private sector or their efforts. I analyze available scientific evidence and come to my own conclusions. 

Over the past four decades the number of livestock and poultry farms in the United States has decreased while the number of animal units produced has increased. The USDA Economic Research Service reports that between 1982 to 1997, the number of farms in the United States with confined animals decreased by 51% from 435,000 farms in 1982 to 213,000 farms in 1997. During this same period however, the number of animal units (where one animal unit is defined as 1,000 lbs of live animal weight) increased by 10% (Gollehon, et al, 2001). The overall decrease in farms with confined animals was due to decreases in the number of farms classified as very small or small in size. At the same time, farms classified as medium and large increased in number. During this period, the number of farms with over 1,000 animal units doubled in the United States. It is important to note that the increase in animal numbers during this period was due to an increase in the number of large farms, and not an increase in the size of large farms. Plainly stated, the clear trend in the US is that animal production has shifted away from many small farms to an increasing number of larger farms.

The reorganization of the US livestock and poultry sector away from smaller farms and into larger farms raises the question; are large farms bad for the environment ? A by-product of any animal production farm is manure. Manure contains both organic matter and nutrients. When manure is applied at agronomically appropriate rates as a crop fertilizer, it increases biological activity in soils, improves physical soil properties and provides valuable nutrients required for crop production. The environmental benefits associated with land application of manures are well documented and include increased soil water and nutrient holding capacity, increased water infiltration, improved soil aeration and reduced soil erosion (CAST, 1992). The ability for manure to become an environmental pollutant when it is released into waterbodies or the atmosphere is equally well documented. The organic matter, nutrients, bacteria and salinity in manure can become an environmental pollutants if they are allowed to reach surface and groundwater supplies (CAST, 1992).

To compare the potential environmental impact of small or large farms, the management of the manure by the farm must be considered. Manure becomes an environmental pollutant if it is miss-managed and allowed to enter streams and waterbodies. As such, the proper management of manure is of critical importance. If we compare a single small farm to a single large farm, it is clear that the larger farm will produce a greater amount of manure. It is the management of the manure on a given farm that determines if the manure is an environmental benefit or determent however. For the same level of animal production however, one large farm and several small farms will produce the same amount of manure. On the large farm the management responsibility lies with one farm for all of the manure, while for the same production level by several smaller farms, the management of an equivalent amount of manure would be distributed between several smaller farms.

Based on a survey of 391 Minnesota swine producers of various sizes, it was found that farm size had a statistically significant effect on manure management practices (Schmitt, et al, 1996). This peer-reviewed study reported that the level of manure management implemented on the farm increased with farm size. The study found that as farm size increased, so did the frequency of analytical testing to determine manure nutrient values, manure application equipment calibration, application during the appropriate time, sub-surface injection increased over broadcast spreading and manure application record keeping increased. The study findings indicate that larger farms implement more comprehensive manure management practices than smaller farms. If we consider the regulatory structure in place for animal feeding operations, the findings of the Schmitt study are not surprising. The storage and land application of manure is regulated on larger livestock and poultry farms. In addition to the fact that large farms must comply with stricter regulations than smaller farms, larger farms are more often able to employee personnel, or contract with consultants, who specialize in manure management to better address manure management issues.

In summary, while manure from any size livestock or poultry operation has the potential to be an environmental pollutant if miss-managed, it also has the potential to replace inorganic fertilizer and provide environmental benefits when managed correctly. As such, it is not farm size that determines if a livestock or poultry operation has a good or bad impact on the environment, but rather it is the management of the manure generated by a given farm. Well managed large farms with good nutrient management plans in place and that comply with state and federal regulations are just as sound environmentally as several small animal production farms that produce a similar number of animals. In fact, data collected to date suggests that large farms as a group may practice better manure management than smaller farms as a whole.

_References:

_{Council for Agricultural Science and Technology (CAST). 1992. Water quality: Agriculture’s role. CASTRep. 120. Ames, IA.
Gollehon, Noek, Margriet Caswell, Marc Ribaudo, Robert Kellogg, Charles Lander, and David Letson. 2001. Confined Animal Production and Manure Nutrients. Agriculture Information Bulletin No. (AIB771) 40 pp, June 2001. Economic Research Service, USDA.
Schmitt, M. A., D. R. Schmidt, L. D. Jacobson, 1996. A Manure Management Survey Of Minnesota Swine Producers: Effect Of Farm Size On Manure Application. Applied Engineering In Agriculture. Vol. 12(5):595-599}

 

Are large farms bad for the environment?? If one listens only to the general public print and broadcast media sources, you would probably say yes. However, if one takes a more in depth and scientific look at size (# of acres and/or animals owned and operated by a single farm) only, there are valid arguments that large farm are no worse at harming the environment than small farms.

First of all, let’s define large farms. Turns out that this is not an easy question to answer. The average farm size by area from the latest National Agricultural Statistics Service (NASS) report (Feb, 2008) is 418 acres. However, for the U.S., this farm area size varies greatly by state from 2,700+ acres in Montana to 57 acres in Rhode Island. So a large farm in one of the Northeastern states (say 500 acres) would be a small farm in one of the western states!!

For animal production operations, it may be a little easier to define what might be considered large. The Environmental Protection Agency (EPA) has come up with a common unit to “size” livestock and poultry operation that is called an animal unit (AU). This is defined as 1000 lbs of animal live weight. So a 1000 lb beef steer would be one AU while four 250 lb pigs (4x 250 lbs = 1000 lbs) would also be one AU. The EPA has defined a Confined Animal Feeding Operation or CAFO, as a farm having 1000 AUs, which the animal production industry, regulatory community, environmental groups all defines as large.
There are other criteria that might be used. Again the NASS report divides up the U.S. farms into economic (annual) sales classes. These are between $1,000 and $10,000, between $10,000 and $100,000, between $100,000 and $250,000, between $250,000 and $500,000, and finally those farms that have annual sales > $500,000. In 2007, the NASS report estimated there were 1.22 million farms in the first economic class (between $1,000 and $10,000) while there were 126,000 farms in the fifth class (> $500,000). These are gross sales figure and most economists would estimate that nearly all farms only would have net or profit figures from 10 to 30 % of their gross receipts, so if someone wants to be a full-time farmer they will probably need to have sales at least above $100,000 and possibly over $250,000, especially if they have debt to service and want a reasonable living expense for themselves and their families.

How about the question of impacting the environment? Production agriculture operations or farms could impact the environment by degrading the nation’s soil, water, or air. Let’s look at each separately.

Production agriculture uses soil as one of its main resources to produce food (plants directly and animals indirectly). Crops remove nutrients and they must be replaced to maintain a sustainable soil system. Also, some cropping practices (and maybe some animal grazing practices) may promote soil erosion through water or wind forces. So soil can be degraded by excessive nutrient removal (mining) and/or soil erosion. Almost every farm, large or small, will maintain the soils nutrients by the addition of natural (cover crops), organic (animal manure), or chemical fertilizers otherwise it will not produce the crops planted. Similarly, soil conservation practices such as contour farming, wind breaks, and vegetative buffer strips are practiced or built on both large and smaller farms. I’m not aware of a breakdown by size of farms from the Natural Resource Conservation Service (NRCS) on who receives cost share funding to implement the soil conservation practices mentioned above but I think it is farms of all sizes and might even favor larger farms. Therefore, I believe the statement that large farms are bad for the environment as pertaining to impact on the nation’s soil is misguided.

Obviously, farms need lots of water, either if they raise crops or produce animal products. Larger farms may need to draw from either surface or ground water sources to irrigate crops or water livestock or poultry so they may locally impact the quantity of water more than smaller farms, but when expressed on a per unit of production (bushel of crop or lb of milk or meat) this would not be different than for small farms. So barring some very local situations, the perception that large farms are bad for water quantity is also misguided.

The situation for water quality is more complicated. Larger farm certainly have greater potential to negatively impact water quality no matter if they produce only crops (larger fields and probably a higher usage of commercial fertilizers and other chemicals than smaller farms). However, on the positive side, large farm often participate in more conservation programs that reduce erosion (runoff to surface waters). Large farms often have more modern and high-tech machinery that practice so-called precision farming (apply only the fertilizer and herbicide/pesticide needed by the crop / land). Small farms, because of smaller equipment and fields may leave existing vegetative buffers along fence rows and windbreaks that would restrict field runoff. Conservation practices that are advocated by such governmental service as the NRCS are available to all size operations but do have funding limits that might restrict implementation on large farms.
For animal operations, large farms (>1000 AU) are required by EPA regulations to have nutrient management plans (NMP) which forces them to apply their animal manure produced on these operations at agronomic rates based on nitrogen (N) or in some cases phosphorous (P) levels in the manure onto cropland (their own or to someone they have a contractual agreement). Depending on the state, some smaller livestock farms under 1000 AU are also required to develop and use NMP but most states these are not required for small farms (< 100 or 50 AU). Thus, although they again have potential to impact water quality, because of regulations and the large financial incentive to use this resource (animal manure) wisely, the perception that large farms (crop or animals) have a greater negative impact on water quality is again misguided.

Finally the issue of air quality. Here, I believe large farms, especially animal operations, have a problem (Jacobson, 2007). Because large CAFO’s concentrate animals in a single location they often produce large single source emissions of gases, odors, and particulates from the animal buildings and any associated manure storage / treatments systems. These can have local (odor), regional (acidification of vegetation and surface waters), and global (climate change) impacts. Most damaging of these are the local and regional impacts since the global (greenhouse gases – GHG) effects would be cumulative even for small farms. Small livestock and poultry operation will also produce emissions but typically are sufficiently low that their impact is considerably less on the environment. Also, crop farms can impact air quality by the emissions of particulates or dust from fossil fuel sources such as tractors, irrigation engines, or through tillage practices. Mitigation technologies are being developed to reduce air emissions from animal operations and even crop farms, but these are expensive and typically need more developmental work before they become commonly used on farms. So at this time, when it comes to air quality issues, I believe the statement that large farms are bad for the environment is plausible.

In summary, for soil and water quality components, I believe the statement that large farms are bad for the environment is misguided but for air quality this statement is plausible.

_References:

_{National Agricultural Statistics Service (NASS) report (Feb, 2008). Farms, Land in Farms, and Livestock Operations 2008 Summary (available on web).}

_{Environmental Protection Agency website ( “http://cfpub.epa.gov/npdes/afo/info.cfm“). “General Information on Concentrated Animal Feeding Operations”}

_{Jacobson, Larry D. (2007) ‘Animal Structures: Air Quality’ Encyclopedia of Agricultural, Food, and Biological Engineering, 1:1, 1-3, DOI: 10.1081/E-EAFE-120007233.}

An abundance of confusion has complicated the use of high fructose corn syrup (HFCS) since it was introduced as an industrial sweetener – a substitute for sugar – in the 1960s.

Some of the controversy derives from the dramatic increase in the prevalence of obesity in the US (and in the rest of the world). The numbers of obese people started rapidly increasing at about the same time that HFCS became available as a substitute for sugar in the production of hundreds of sweetened food products; most notably in soft drinks. The simultaneous occurrence of these two events is striking and it is tempting to relate the one to the other. (1)

Some of the controversy also derives from the selection of its name, high fructose corn syrup, by the chemists who created it. They were tinkering with the process of creating sugar from corn. Table sugar, sucrose, is a chemical compound containing equal parts of two smaller sugar molecules, glucose and fructose. Until 1968 the sugar derived by deconstructing the complex corn starch molecule yielded glucose alone. Mechanisms were developed then to convert some of that glucose to fructose. Eventually, the chemists were able to increase the production of fructose so that the mixture contained equal amounts of glucose and fructose, comparable to table sugar. Pleased with their achievement of increasing the fructose content of corn syrup, the new product was given the unfortunate and misleading name “high fructose corn syrup.” Quite reasonably, HFCS is thought to contain high amounts of fructose, with all of the assumed consequences which derive from high amounts of fructose. Higher, yes, than corn syrup alone, but not higher in fructose than ordinary table sugar. HFCS is the equivalent of table sugar, nutritionally, chemically and functionally. It does not have significantly high fructose content if you compare it to sucrose which is what it replaces in so many of the foods we eat

Most of the commercial HFCS now being used in the US contains either 42% or 55% fructose. (Table sugar is 50% fructose.) These different products have slightly different properties in commercial food production but their endocrine, metabolic and nutritional effects are similar. There are no differences in comparing sugar and HFCS in their impact on appetite or on levels of blood sugar, insulin or on a variety of metabolic measurements or hunger signaling hormones. (2,3)

If you consume an ordinary sugar-sweetened beverage your intestinal tract rapidly splits the sucrose molecule into its two component molecules, glucose and fructose; equal amounts of each. The process is simple, quick and complete. The body then processes the glucose and fructose in exactly the same manner as it processes the two components of HFCS. Actually, in a mildly acidic soft drink the chemical breakdown of sucrose to glucose and fructose starts spontaneously in the bottle (or can) on the shelf and may even be substantially complete before it is consumed depending on the acidity of the drink, the temperature and the time on the shelf.
The realization that obesity is increasing with equivalent rapidity in many parts of the world in which HFCS is not commercially available further undermines the argument that HFCS is a cause of obesity. (4) If HFCS were a factor which contributes to obesity, one could not establish that it is a necessary condition for the weight gain of populations not exposed to HFCS.

Although the population statistics establish that the dramatic increase in the prevalence of obesity coincided with the substitution of HFCS for sucrose, the logical conclusion is that, since there is no difference in the two sweeteners, there is no reason to blame HFCS for obesity. HFCS seems, then, to be functionally identical to table sugar and it should be easy to say that HFCS is not any greater a culprit than sucrose; and to conclude that obesity is not caused by HFCS. Isn’t the temporal association just a mere coincidence?

As with all controversies in science, it really is not that simple. It gets complicated for three linked reasons.

First, HFCS lowers the cost of sweetening foods and producing certain kinds of foods and beverages. With lower costs we have increased consumption. This is particularly true for HFCS sweetened beverages. If the cost of it is kept low more of it gets used, or, at the least, cost is less of an obstacle in purchasing decisions. HFCS is not the culprit, no more than sugar, but it is an innocent participant in the complex process of manufacturing and selling food. To assume, however, that the availability of an inexpensive sweetener causes obesity would be comparable to assuming that the availability of cheap weapons is why we have wars.

Second, the human brain controls calorie intake in response to calories consumed. Although we assume that eating is merely a matter of choice, eating is actually largely regulated by an array of complex brain signals. The brain measures food (calorie) intake and then transmits start and stop eating signals. But, for reasons poorly understood, the brain fails to recognize liquid food calories as well as it recognizes solid foods calories. (5) Liquids are more of a menace for calorie control than solids. If HFCS (or sugar) is put into a beverage it will contribute more to your total daily calorie consumption than the same amount of HFCS or sugar consumed as jelly beans or pastry. The body’s regulatory system gets clearer feedback signals from calories consumed as food than it does from calories consumed as liquid. The amount of HFCS or sugar consumed in soft drinks contributes disproportionately to our community’s consumptions of calories.

Finally, fructose seems to be a particular culprit in weight gain, but again, it’s an equal opportunity culprit, and the brain doesn’t seem to care if the fructose comes from sugar or HFCS. Fructose does not signal the body’s control mechanism as effectively as does glucose. If we consume more sweetened foods, particularly more sweetened drinks, we are going to get more calories, more sugar or HFCS, and we will get more total fructose. The name, high fructose corn syrup, is misleading, suggesting that it contains a disproportionately high amount of fructose. It does not, compared to table sugar. But, an increased total consumption of beverages means more of everything and a pattern which predicts more weight gain.

There is no dispute that weight management mandates decreasing the consumption of high calorie foods, particularly sweetened foods, and more so with beverages sweetened with sugar or HFCS. Nevertheless, there is no metabolic, nutritional or chemical reason to assign unique responsibility to HFCS. For weight management, it’s every bit as bad as sugar, but not worse.

1. Bray GA, Nielsen SJ, Popkin BM. Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity. Am J Clin Nut. 2004; 79: 537-43.

2. Melanson KJ, Zukley L, Lowndes J, Nguyen V, Angelopoulos TJ, Rippe JM. Effects of high-fructose corn syrup and sucrose consumption on circulating glucose, insulin, leptin, and ghrelin and on appetite in normal-weight women. Nutrition. 2007; 23: 103-12.

3. Stanhope KL, Griffen SC, Blair BR, Swarbrick MM, Keim NL, Havel PJ. Twenty-four hour endocrine and metabolic profiles following consumption of high-fructose corn syrup-, sucrose-, fructose-, and glucose-sweetened beverages with meals. Am J Clin Nut. 2008; 87: 1194-203.

4. Forshee RA, Storye ML, Allison DB, Glinsmann WH, Hein GL, Lineback DR, Miller SA, Nicklas TA, Weaver GA, White JA. A critical examination of the evidence relating high fructose corn syrup and weight gain. Crit Rev Food Sci Nut. 2007; 47: 561-82.

5. DiMeglio DP, Mattes RD. Liquid versus solid carbohydrate: effects on food intake and body weight. Int J Obes Relat Metab Disord. 2000; 24: 794-800.

There will be no bacon shortage. The price may be higher, but the bacon will be there. This rumor started in England, I am told, and came here. The pork industry does not like the feed prices, but they are still hard at the task of ‘makin’ bacon.’ You can have as many BLTs as you wish!

U.S. farm policies have had a negligible effect on the consumer price of food and food consumption. While many arguments can be made for changing farm subsidies, entirely eliminating the current programs would not have any significant influence on obesity trends.

Obesity has increased rapidly in the United States and in many other countries. The proximal cause of obesity is simple and not disputed: people consume more food energy than they use. Farm subsidies could have contributed to lower relative prices and increased consumption of fattening foods by making certain farm commodities more abundant and therefore cheaper. However, each of several component elements must be true for farm subsidies to have had a significant effect on obesity rates.

• First, farm subsidies must have made farm commodities significantly more abundant and cheaper.
• Second, the lower commodity prices caused by farm subsidies must have resulted in significantly lower costs to the food industry
• Third, the cost savings to the food marketing firms must have been passed on to consumers in the form of lower prices of food.
• Fourth, food consumption patterns must have changed significantly in response to these policy-induced changes in prices.

In fact, the magnitude of the impact in each of these steps is zero or small, so the overall effect is negligible. Let us consider each step briefly.

First, farm subsidies have had very modest (and mixed) effects on the total availability and prices of farm commodities that are the most important ingredients in more-fattening foods. U.S. farm subsidy policies include both Farm Bill programs and trade barriers that raise U.S. farm prices and incomes for favored commodities. These policies support farm incomes either through transfers from taxpayers, or at the expense of consumers, or both. Thus, they might make agricultural commodities cheaper or more expensive and might therefore increase or reduce the cost of certain types of food. Indeed, for several important food products (dairy, sugar, and orange juice) that have been associated with obesity, barriers to imports are used to raise the prices paid by consumers in order to support the prices received by producers. In fact, balancing the effects of these types of policies with policies that make other food commodities cheaper (such as corn, wheat, and soybeans), the effect of farm price support policies has been to make food commodities overall a little more expensive for buyers.

Second, such small commodity price impacts would imply very small effects on costs of food at retail, which, even if fully passed on to consumers, would mean even smaller percentage changes in prices faced by consumers. The cost of farm commodities as ingredients represents only a small share of the cost of retail food products; on average about 20 percent, and much less for products such as soda and for meals away from home, which are often implicated in the rise in obesity. Hence, a very large percentage change in commodity prices would be required to have an appreciable percentage effect on food prices.

Third, given that food consumption is relatively unresponsive to changes in market prices, the very small food price changes induced by U.S. farm subsidies could not have had large effects on food consumption patterns. Simple causation from farm subsidies to obesity is also inconsistent with international patterns across countries. For example, obesity trends for adult males and children in Australia are similar to those in the United States, but Australia phased out its farm commodity programs, over the 1980s and 1990s.

Corn is often the target of criticism as a contributor to obesity, especially because of its use to make high fructose corn syrup (HFCS) which is used as a caloric sweetener in many foods and beverages. The use of HFCS as a sweetener has been encouraged by U.S. sugar policy that made sugar much more expensive and gave food manufacturers economic incentive to substitute HFCS for sugar. Corn itself does receive subsidies that encourage production and have made it cheaper and more abundant for consumers in the past. But even for corn the subsidies have not had a very large effect—increases in availability and reductions in buyer prices for the farm commodity of well less than 10 percent in the years of greatest subsidy, and much less than that in recent years given the high world market prices and the demand for corn as feedstock for ethanol plants. Most corn is actually consumed in the form of meat or dairy products. Corn and other feedstuff represent less 8 percent of the retail cost of meat such that a 10 percent cut in the farm price of corn would imply at most a 0.8 percent reduction in the retail price of meat facing consumers. Similar calculations apply for other retail foods. Consequently, eliminating corn subsidies could not be expected to have large and favorable effects on consumer incentives to eat more-healthy diets such that obesity rates would be meaningfully reduced.

The sweetener market merits some explicit discussion. Farm subsidies are responsible for the growth in the use of corn to produce high fructose corn syrup (HFCS) as a caloric sweetener, but not in the way it is often suggested. The culprit here is not corn subsidies; rather, it is sugar policy that has restricted imports, driven up the U.S. price of sugar, and encouraged the replacement of sugar with alternative caloric sweeteners. Combining the sugar policy with the corn policy, the net effect of farm subsidies has been to increase the price of caloric sweeteners generally, and to discourage total consumption while causing a shift within the category between sugar and HFCS. In this context, eliminating the subsidy policies would result in cheaper caloric sweeteners and, if anything, more rather than less total consumption of sweeteners, with a switch in the mix back towards sugar.

Farm commodities have indeed become much more abundant and cheaper over the past 50 years in the world as a whole as well as in the United States, but not because of subsidies. This abundance mainly reflects the effects of technological innovations and increases in farm productivity that have rescued billions of the world’s poor from the shackles of poverty and starvation, while at the same time reducing pressure on the world’s natural resources. If cheaper and more abundant food has contributed to obesity, then we should look to agricultural innovation rather than farm subsidies as the fundamental cause. Even so, it would be a dreadful mistake to seek to oppose and slow agricultural innovation with a view to reducing obesity rates. Conversely, though it might be beneficial in other ways, eliminating U.S. farm subsidies would have negligible consequences for obesity rates. The challenge for policy makers is to find other—more effective and more economically rational—ways to reduce the social consequences of excess food consumption while at the same time enhancing consumption opportunities for the poor and protecting the world’s resources for future generations.

_{Further Reading}

_{Alston, J.M., D.A. Sumner, and S.A. Vosti. “Are Agricultural Policies Making Us Fat? Likely Links between Agricultural Policies and Human Nutrition and Obesity, and Their Policy Implications.” Review of Agricultural Economics 28(3)(Fall 2006): 313-322.}

_{Alston, J.M., D.A. Sumner, and S.A. Vosti, “Farm Subsidies and Obesity in the United States: National Evidence and International Comparisons.” Food Policy 33(6) (December 2008): 470-479.}

The popular agrarian vision of US livestock farming involves a small family farm with animals grazing on sunlit pasture, a farmer in bib coveralls and a gable-roofed red barn in the background. Self-proclaimed food experts and activist organizations often embrace this vision, suggesting that a return to the agricultural systems of yesteryear will provide solutions to current economic, environmental and nutritional issues ranging from the energy crisis (Pollan, 2008) to global warming (Koneswaran and Nierenberg, 2008) and obesity (Pimentel et al., 2008).

During the 20th century, average farm size increased from 146 acres to 487 acres and US farm numbers decreased from 5.7 million to 1.9 million (USDA/NASS, 2009). Small farms account for 91 percent of all farms, however, due to low productivity, these farms only account for 23% of total US agricultural production (Hoppe et al., 2010). Interestingly, in recent years the agricultural industry has seen a reduction in the number of medium-sized farms (Ahearn et al., 2005) while the numbers of large and small farms have increased. It is worth noting that despite changes in farm size, 98% of US farms are currently classified by the USDA as family farms, and these farms account for 85% of production (USDA/ERS, 2007). Just as moving from draft horse-power to mechanized tractors and equipment allowed farmers to produce greater crop yields using considerably less manual labor and time, increased farm size allows for financial and physical economies of scale (McDonald and McBride, 2009) and greater profit margins (MacDonald et al., 2006, USDA/ERS, 2007). Large and small farms fulfill differing roles – large farms produce significant volumes of food for widespread consumption, whereas small farms often cater to niche markets or are considered retirement/lifestyle farms (USDA/ERS, 1999), with heavy reliance on off-farm income (Hoppe et al., 2007).

Individual farms may differ in terms of efficiency, but the overall effect of changing from small-scale to large-scale production is to improve productivity (McDonald and McBride, 2009). This is exemplified by the poultry and swine industries, where vertical integration has allowed for specialization and improved efficiency within every tier of the production system (Ahearn et al., 2005). Within the non-integrated dairy and beef industries, increasing farm size has also had a positive effect on productivity. The USDA National Animal Health and Monitoring Service reported an 3,965 lb increase in annual milk production per cow in large herds (>500 cows) vs. small herds (<100 cows). This is largely driven by specialized management – a 100 cow dairy herd may have two or three farm workers (owners or employees) who are responsible for all tasks, a 1,000 cow herd can employ specialized labor to improve the efficiency of each component of the system. Moving back towards an agricultural system containing many small farms would have a major impact on the amount of labor required per unit of food produced – it is no coincidence that as average farm size increased, the percentage of the population employed in agriculture decreased from 39% in 1900 to less than 2% in 1990 (USDA/NASS, 2009). The question thus remains, in a society largely disconnected from agricultural production, if farm size regresses, where will the extra labor be found?

Productivity is a crucial contributor to the environmental impact of food production. Regressing from a highly efficient feedlot beef system to a low-input pasture-based system may appear to be more eco-friendly, but due to reduced growth rates, pasture-finishing increases energy use by 2.8x, methane production by 2.5x and land use by 12.6x per lb of beef (Capper et al., 2009a). Over the thirty years between 1977 and 2007, beef production (expressed as lb beef per animal slaughtered) increased from 604 lb to 774 lb, allowing the industry to produce 2.9 billion lb more beef from 5 million fewer slaughter animals. Within the dairy industry, annual milk yield per cow increased from 4,800 lb in 1944 to 20,300 lb in 2007 allowing 59% more milk to be produced using 64% fewer cows. Reducing the herd size required to produce a set amount of milk or beef reduces resource use and GHG emissions per gallon of milk or lb of beef. Indeed, the productivity improvement between 1944 and 2007 reduced the US dairy industry’s total carbon footprint by 41% (Capper et al., 2009b). As noted by a recent FAO report, in order to reduce environmental impact there exists “a need for continued efficiency gains in resource use for livestock production” (Steinfeld et al., 2006).

The reduction in productivity (yield per acre, per animal or growth rate) associated with small farms increases the environmental impact of food production. This would be further exacerbated if the current popularity of ‘locovorism’, i.e. purchasing food produced within the local area (often defined as a 100 mile radius from home) continues to grow. Relying upon ‘food miles’ (i.e. the distance food travels from production facility to consumer) as a measure of environmental impact has significant negative consequences, as transport accounts for a relatively small percentage of total energy use and GHG emissions and is directly dependent upon the productivity of the system. Capper et al. (2009a) compared the fuel use associated with purchasing one dozen eggs under three scenarios: the local chain grocery store supplied by a large-scale production facility some miles away; 2) a farmer’s market supplied by a source much closer than the grocery store’s source; or 3) directly from a local poultry farm. The total ‘food miles’ associated with the grocery store eggs were considerably higher (1,603 miles) compared to the farmers market (186 miles) or local poultry farm (54 miles) and the fuel efficiency was lowest in the grocery store example which employed a refrigerated tractor-trailer compared to the local farm example (average passenger car. However, the productivity of the refrigerated trailer as a mode of transport (23,400 dozen egg capacity) compared to the passenger car reduced the fuel use per dozen eggs from 2.4 gallons when buying from the local poultry farm, to 0.63 gallons for the farmers market to 0.14 gallons for the grocery store eggs.

Changes in the structure and regional location of different food production systems have occurred in response to differing land resources, animal species and climate (Diamond, 2005). Moving towards a small farm system whereby all foods are produced locally would mean that consumer food choice would be severely curtailed and food production decoupled from resource availability. The potential inefficiencies associated with such a system would have a significant environmental and economic impact as well as retarding the ability of US agricultural producers to fulfill the population’s demand for food.

The small-scale, extensive farming systems of yesteryear were ideally suited to supply the milk and meat requirements of the US population in the 1930’s and 1940’s. As the population grows and competes with agriculture for land, energy and water resources, the need to improve efficiency and productivity becomes ever more crucial. This can only be achieved by continuing specialization and intensification. Small farms will continue to occupy a small niche within food production, but are not a sustainable or practical solution for the economic and environmental issues currently facing US agriculture.

_References

_{Ahearn, M. C., P. Korb, and D. Banker. 2005. Industrialization and contracting in US agriculture. Journal of Agricultural and Applied Economics 37:347-364.}

_{Capper, J. L., R. A. Cady, and D. E. Bauman. 2009a. Demystifying the environmental sustainability of food production. in Proceedings of the Cornell Nutrition Conference. Cornell University, Syracuse, NY.}

_{Capper, J. L., R. A. Cady, and D. E. Bauman. 2009b. The environmental impact of dairy production: 1944 compared with 2007. J. Anim. Sci. 87:2160-2167.}

_{Diamond, J. 2005. Guns, Germs and Steel: The Fate of Human Societies. W. W. Norton & Co., New York, NY.}

_{Hoppe, R. A., P. Korb, E. J. O’Donoghue, and D. E. Banker. 2007. Structure and Finances of U.S. Farms – Family Farm Report 2007. USDA/ERS, Washington, DC.}

_{Hoppe, R. A., J. M. MacDonald, and P. Korb. 2010. Small Farms in the United States: Persistence Under Pressure. USDA/ERS, Washington, DC.}

_{Koneswaran, G. and D. Nierenberg. 2008. Global farm animal production and global warming: impacting and mitigating climate change. Environ. Health Perspect. 116:578-582.}

_{MacDonald, J. M., R. A. Hoppe, and D. Banker. 2006. Growing Farm Size and the Distribution of Farm Payments. USDA/ERS, Washington, DC.}

_{McDonald, J. M. and W. D. McBride. 2009. The Transformation of U.S. Livestock Agriculture: Scale, Efficiency, and Risks. USDA/ERS, Washington, DC.}

_{Pimentel, D., S. Williamson, C. E. Alexander, O. Gonzalez-Pagan, C. Kontak, and S. E. Mulkey. 2008. Reducing energy inputs in the US food system. Hum. Ecol. 36:459-471.}

_{Pollan, M. 2008. Farmer in Chief. in New York Times. New York, NY.}

_{Steinfeld, H., P. Gerber, T. Wassenaar, V. Castel, M. Rosales, and C. de Haan. 2006. Livestock’s Long Shadow – Environmental Issues and Options. Food and Agriculture Organization of the United Nations, Rome.}

_{USDA/ERS. 1999. Agricultural Outlook: What Makes a Small Farm Successful? USDA/ERS, Washington, DC.}

_{USDA/ERS. 2007. America’s Diverse Family Farms. USDA/ERS, Washington, DC.}

_{USDA/NASS. 2009. Trends in U.S. Agriculture. http://www.nass.usda.gov/Publications/Trends_in_U.S._Agriculture/. Accessed: March 2010.}

The two most common arguments used in favor of farm subsidies are either that farmers would go out of business if they were eliminated and that farm subsidies are responsible for the fact that Americans spend less of their disposable income on food than any other country.  These two arguments are effective because there is some historical truth to the first argument and the second argument seems to follow the first law of economics that we get more of what government subsidizes.  But a close examination of how farm subsidies work and how farmers make production decisions reveals that their elimination would have little impact on food prices and that while farm subsidies can provide short-run help to farm finances, over time, the most efficient farmers will be making a living from agriculture with or without farm subsidies.

Market prices for farm commodities are determined by how much of a particular commodity is produced and the demand for the commodity.   Production depends on how much land is planted to the crop and the weather during the growing season.  The amount of land devoted to corn, soybeans, wheat, and other crops depends on the relative returns among them. If farmers expect to be able to make more money from corn than soybeans or wheat, then more corn will be planted.  If wheat returns are expected to be high, then more wheat will be planted. 

The importance of relative returns means that if farm subsidies were focused on a particular crop, and farmers needed to plant that crop to obtain payments, then more of the crop would be planted.  Traditional subsidies are delivered directly to producers of the principle field crops (corn, soybeans, wheat, barley, cotton, rice, grain sorghum, oats and peanuts) through farm programs.  All the major field crops that compete with each other for land are subsidized.  Unsubsidized crops mainly consist of tree crops, other fruit, and vegetables which are not strong competitors for land with the subsidized commodities.  Because subsidies increase the relative returns of all land-competing crops, not just a chosen few, the impact of farm subsidies on relative returns is generally minor.  This means that the mix of the major crops grown is not significantly affected by farm subsidies.

But subsidies can increase the overall profitability of farming because they increase farm revenue.  The most direct impact of higher profitability is that it increases the ability of farmers to buy or rent land, which, in turn, increases the price of land.  Subsidy-induced increases in the price of land do not enhance farmers’ ability to make a living.  For farmers that do not own land, land price increases are just an increase in the cost of production. For farmers who own land, land price increases help their balance sheet, but they do not help cover production costs.  Put more simply, higher land prices increase the returns to owning land but not the returns to farming. 

A secondary impact of subsidies is that they can induce farmers to plant more crops by shifting land out of pasture or other grassland into crop production.  Cropland expansion will result if farm subsidies are tied directly to production levels. That is, if farmers must produce a crop to receive a subsidy then they are likely to produce more crops. 

But in 1996, traditional farm programs largely broke the link between production levels and farm payments by basing payments on what farmers produced in the past.  The link is not completely broken because if prices get low enough, farmers enjoy the benefits of a floor price that protects all of their production. But these floor prices are so low that when market prices fall below these floor prices, high-cost farmers cut acreage rather than produce for the floor price. 

Thus, both the total amount of land devoted to crop production and the mix of crops is largely unaffected by the existence of farm programs.  This means that crop prices-hence food prices-would change little if all farm programs were eliminated.  There simply is no truth to the argument that farm subsidies benefit consumers by lowering the price of food. Inexpensive food has resulted from improved seed varieties, better farm management practices and herbicides, more efficient food processing technologies and improved logistical networks, not farm subsidies.

A portion of farm payments run counter to market prices.  When market prices fall below the floor price (the commodity loan rate), then farmers receive compensatory payments that make up the difference.  Farm prices can fall dramatically, usually because of bumper crops or because of a sharp drop in export demand.  Farmers who have made production and investment decisions based on the expectation of high prices can face financial trouble when market prices unexpectedly fall, particular when prices stay low for a number of years.  For example, farm prices fell dramatically in the mid-1980s and from 1998 to 2001.  The infusion of farm payments during these periods kept some farmers from having to declare bankruptcy and helped the balance sheet of all subsidized farmers. Thus there is some truth to the argument that some farmers have needed farm programs to stay in business.

A general characterization of farm programs is that when crop prices are high they deliver payments to farmers when the payments are not needed and when prices are low, they automatically provide a government bailout to a portion of producers who grow subsidized crops who otherwise would have to go out of business.  But government bailouts are not permanent solutions. If GM does not produce high quality cars that consumers want to buy, it has no future despite its government bailout.  Similarly, the discipline of the marketplace means that the most efficient farmers will be the farmers who make money from farming, with or without government help during tough times. 

Thus, there is some truth to the statement that some farmers need farm payments to stay in business when prices are low and stay low, but over time, farm payments do not determine which farmers make a living from agriculture.  The fact that farm programs have allowed some farmers to survive tough times does not mean that a significant amount of land would have remained idle had the programs not been in place. Land rents would have fallen and surviving farmers would have immediately expanded their own farm operations.  Thus food prices and aggregate production are largely unaffected by the existence of farm programs.

One often hears the statement  “The food supply of the United States is the safest in the world”.   This is a hard statement to support in view of the fact that the food supply of the United States is comprised of both domestically produced foods and imported foods and ingredients from over 150 countries.  Should we be concerned about the safety of foods imported into the U.S. or is imported food just as safe as the food we produce ourselves?

Foods produced and processed in the most industrially developed countries such as the United States, Canada, Australia/New Zealand and the European Union (EU) are similar in quality and safety.  However, food produced, processed and exported from developing nations varies widely in quality and safety depending on the standards implemented and enforced by their governments or trade associations.  The US imports approximately 78% of fish and seafood products and approximately 31% of all fruit, fruit juices and nuts. (5)  These items are primarily imported from countries where sanitary standards may, or may not be up to US standards.  One of the most common causes for rejection of seafood imports is “filth”. (4)  This can create valid concerns about the safety of imports from developing countries.

Chile is a good example of a less developed country that has taken steps to protect their massive fruit and vegetable export market.  They have established food safety programs based on and comparable to those of the US Good Agricultural Practices (GAP) (1).  Chile has some of the most comprehensive GAP programs in the world. They include use of modern production and handling practices, strict control of pesticides, residue monitoring, state-of-the-art packaging, well maintained storage facilities and a constant emphasis on worker hygiene and sanitation. 

Producing high quality and safe foods in every country, especially developing countries presents additional challenges.  For example, developing countries may lack sanitary water supplies or be faced with extreme levels of pollution in their water supply.  Neither the food safety infrastructure nor the educational programs regarding food safety and sanitation may be comparable to the US. 

Programs like GAP  and  Hazard Analysis Critical Control Point (HACCP) systems are widely used in the U.S. to help ensure safe transportation, production and processing practices in handling food but getting them established and implemented in developing countries exporting to the U.S. is often difficult.   In addition to industry and regulatory commitment, all of these food safety programs depend on one paramount source to achieve implementation – revenue.   With the current global recession, finding additional funding for safety inspectors and services is often put on the back burner. 

For a country to produce, process and export safe high quality food, a stable government is essential. (7)  Countries that have these standards – like the US, Canada, the EU nations, Australia and New Zealand – tend to base their consumer protection programs on three key areas:  (1) food safety legislation, (2) regulations based on sound science and (3) enforcement of food laws– particularly laws that control safety and sanitation.  Producing safe food requires shared understanding among government agencies and clear communication between government and industry.   A stable and responsible regulatory infrastructure certainly enhances the efforts to keep food safe – not always an easy task – even for highly developed countries.  (7)

With the increasing number of recalls in the news lately, many Americans are wondering if their food supply is safe.  The massive number of recalls involving products containing peanut butter produced by the Peanut Corporation of America (largely recalled in 2008) underscores these trepidations.  Food products and feeds produced with ingredients from China involving the use of melamine—a toxic nitrogen based chemical – added to the fears.  American consumers turn on their TV and computers nightly to watch and read about these problems – and they worry – rightfully so. People got sick and people died from eating unsafe food.  

In the weeks between May 1 and May 31, 2009, there were at least 20 recalls associated with food products announced by the US Food and Drug Administration (FDA) or USDA.  Recalls of pistachio nuts, alfalfa sprouts and cantaloupe – all positive for Salmonella – voluntarily recalled by food companies – with no reported illnesses were announced (4).   Some of these products came from countries like Chile (lemon pistachio) and some came from the U.S.

There are routinely recalls due to labeling and allergen issues such as unlabeled additions of milk and peanuts to food products. (4)    Over $1.5 million of adulterated (filthy) food ingredients was seized by US Federal Marshals from the American Mercantile Corp of Memphis, Tennessee at the request of the FDA  on May 7, 2009.  (2)  The most important point to remember is that there have been no reports of illness from these foods. (4)   Our food safety system is working even though it is not perfect.

The US imports food from over 150 countries in the world – through approximately 300 ports of entry including land, sea and air. (5)   Examination of data on imports  refused by the FDA  just in the month of April 2009 (3),  showed that 250 were
rejected from China –  mostly for melamine contamination.  Other countries had sizable number of exports rejected in the month of April including India (122), Mexico (146), Japan (53), Korea (50), Viet Nam (48),  EU countries (~133),
Canada (89),   Chile (33) and Australia (7). 

So, the FDA and USDA are keeping a lot of harmful food products out of the US. However, as diligent as their efforts are, it is a daunting task to keep everything that might be harmful from entering America.  This is mainly due to the cost and lack of personnel required to police such massive shipments of food and the time and resources needed to test each shipment of food – some of which is highly perishable such as fruits and vegetables.
           
Proponents of the EU food system argue that the EU  has higher standards of food safety than the US.  Genetically modified foods,  animal hormone use and standards for certain toxic chemicals like aflatoxins are more strict in the EU.  However, the EU is hampered in establishing and enforcing both these and traditional food safety regulations since the 27 countries of the EU sometimes lack a shared understanding or uniformity in enforcement of regulations. (7)  Food safety regulatory authorities in each EU country are not identical and the languages of the law. . not to mention translation. . often impede efforts in uniformity of enforcement.  The EU thrives on a global flow of goods. (7)  Anyone who tries to block that flow risks criticism and occasionally opposition by the “offended” country.   

Through the Centers for Disease Control and Prevention (CDC), the United States has the best and most transparent foodborne disease surveillance and documentation of foodborne illnesses in the world.  The  CDC has led the way in developing methods to identify and track foodborne disease outbreaks with their PulseNet USA system. (6) Initiated in 1996, PulseNet provides a means to identify DNA fingerprints of bacteria involved in foodborne illnesses. This data is provided to the CDC by public health departments.  Once this data is collected and analyzed,  the CDC and regulatory agencies alert the public to a pattern of illnesses.   It was the CDC that sounded the warning that Salmonella was involved with the Peanut Corporation of America products.  It was a timely warning indeed!

Thousands of illnesses and deaths have been avoided by this early warning system.    Health Canada has joined the CDC and formed PulseNet Canada (2000-2003).  PulseNet shares information freely between Canada and the US to track and identify disease outbreaks.  The goal of the developers of these systems is to have an international warning system.  PulseNet Europe was born in 2004. (6)  Certain countries within the EU have excellent surveillance systems – primarily developed by independent and dedicated scientists but prior to 2005 the EU did not have a counterpart to the U.S. CDC (established in 1946).  (7)  The U.S. is fortunate to have an established agency like the CDC with over 50 years of experience in protecting public health and their early warnings help to protect the food supply. 

Providing a high quality and safe food supply for Americans and other people of the world  is a daunting task as the world’s population continues to grow unchecked.  Furthermore, less and less people are involved in the production and processing of food products which means that food production and processing is centralized requiring lengthy transportation of food .  Many of the foods US consumers enjoy travel an average of 1100 miles to reach dinner tables.

Large volumes of food are processed centrally and stored regionally.  Foods and ingredients arrive in the US from over 150 countries using every imaginable type of transportation.  Consumers expect variety, fresh foods, convenience, long shelf-life, optimal taste and nutrition. . .all for inexpensive prices.  Keeping these foods safe while meeting consumer demands is a challenge!

Nonetheless, the USDA and the FDA work consistently with producers and processors in the U.S. and in other countries to set and enforce the standards that provide for safe high quality food.  We help supply the world’s markets and give generously to the poorer nations often rift with famine and hunger.  We set the standards and help monitor the way food is grown, processed, shipped and distributed around the world. 

There is still a lot of room for improvement but overall,  the U.S. food system works as well or better than most countries.  Salmonella remains a constant threat but salmonellosis outbreaks are detected or prevented much more effectively than in the past decade.

Thanks to the efforts of  the U.S. government, regulatory agencies, producers, the food industry and dedicated scientists, the food produced and processed in the US is as safe or safer. . .as that produced anywhere in the world and the U.S. is committed to continually making the food supply safer.

_References:

_{Chilean Fresh Fruit.  About Our Fruit Food Safety Standards.  (http://www.cffausa.org/dev/about_fruit/food_standards/index.php).  Accessed 5/12/09.}

_{FDA.  Over $1.5 million of adulterated (filthy) food ingredients was seized by US Federal Marshals from American Mercantile Corporation of Memphis, TNhttp://www.fda.gov/bbs/topics/NEWS/2009/NEW02012.html. Accessed 5/21/09.}

_{FDA.  OASIS refusals by Country of Manufacture for April 2009.  Food and Drug Administration.  Operational and Administrative System for Import Support (OASIS)  http://www.fda.gov/ora/oasis/4/ora_oasis_cntry_lst.html.  Accessed 5/24/09.}

_{FDA Recalls.  (http://www.fda.gov/opacom/7alerts.html.  Accessed 5/26/09}

_{Jerardo, Alberto.  The US Ag Trade Balance – More than Just a Number.  US Economic Research Service.  Amber Waves 2 (1):  36-41.  2004.}

_{Swaminathan et al.  Building Pulse-Net International:  An interconnected system of laboratory networks to facilitate timely public health recognition and response to foodborne disease outbreaks and emergency foodborne diseases.  Foodborne Pathogens and Disease 3 (1):  36-50.  2006.}

_{Wong, Lo Fo et al.  Food Contamination Monitoring and Food-Borne Disease Surveillance at the National Level.  Proceedings of the 2nd WHO/FAO Global Forum on Food Safety Regulators.  20 pages. http://www.fao.org/docrep/meeting/008/y5871e/y5871e0n (accessed 5/26/09)}

In reacting to the statement, “Meat from Grass Fed Cattle is Safer than Meat from Cattle that are Corn Fed”, the first question that comes to mind is “safer how”? Most consumers think of safety in terms of microbial contamination, hormone and antibiotic residues.

Commercially, cattle are grazed on grass or pasture for some or all of their lives. Many go to feed lots at 12-18 mo of age where they are fed a high carbohydrate grain diet for 4-6 months to increase their growth rate and bring them to market more quickly. In the latter situation, they live in higher density environments and may be treated with antibiotics to treat infections or hormones to increase growth rate. Because their use is under our control, the FDA and USDA have set stringent standards based on exhaustive safety and efficacy testing for antibiotics and hormones in the livestock industry. Because of consumer concerns about antibiotics and hormones, the USDA has certain label claims relative to beef.

No Hormones (beef): Sufficient documentation to show that the animal was raised without hormones.

No Antibiotics (beef): Sufficient documentation to show that the animal was raised without antibiotics.

Certified Organic: Sufficient documentation to show that animals are fed 100% certified organic feed. Some vitamin and mineral supplements are permitted but hormones and antibiotics are not. Animals must have access to pasture but may be finished in a feedlot.

Grass Fed: The Ag Marketing Service established a voluntary claim for grass-fed livestock. It stipulates that animals receive at least 99% of their lifetime energy from a grass- or forage-based diet. Hormones, antibiotics and long-term confinement use are allowed. Verification of the label claim is voluntary. This standard is under consideration by the USDA.

If we consider that the antibiotic and hormone issues are under federal control, and that feeding regimen precludes neither, then the remaining primary concern with beef is microbiological safety. Cattle are asymptomatic natural reservoirs of both harmless bacteria and harmful bacteria (Escherichia coli O157:H7, Salmonella spp., Campylobacter spp.). These pathogens can enter the food supply from cattle via fecal contamination of carcasses at slaughter. In beef cattle, the prevalence of E. coli O157 ranges from <1 to 20% in feedlots and from <1 to 27% on pasture. Hussein (2007). Calves (<3 mo) are more likely to have higher levels of E. coli O157 and Campylobacter spp. in their waste (15). Stocking density has no direct effect on pathogen level.

Rapidly growing (feedlot) and high-producing dairy cattle are fed large grain rations as a calorie source to increase growth rate and milk production. Attempts to correlate the incidence of E. coli O157:H7 (and other pathogens) with specific diets or feeding management practices have resulted in inconsistent findings. It is unclear if diet can influence the survival of E. coli O157:H7 in the gastrointestinal system or in feces in the environment, and if so, whether that has any direct impact on meat derived from animals receiving different diets.

All cattle eat grass for some portion of their lives. Some are fed grains in the months immediately preceding slaughter. Cattle have bacteria in the rumen and gut that break down the cellulose in plant materials. They shed these bacteria continually in their waste. Starch from a corn based diet can escape degradation in the rumen and pass into the colon where it is broken down to sugars. E. coli can ferment these sugars increasing the acidity (lowering pH) in the colon (12). The numbers of acid-resistant E. coli, which are more likely to survive the gastric acidity of the human stomach, can then increase (18). This acid-tolerance could increase the capacity of E. coli to cause human disease. In some studies, E. coli numbers have been higher in grain fed cattle (7) while in others. Feeding corn, with the resultant change in pH, had no relationship to E. coli O157 (8). Some studies report differences due to type of grain in the diet. E. coli O157:H7 prevalence and fecal excretion has been shown to be higher in barley-fed than in corn-fed cattle (5). Other studies have shown that E. coli in feces and ruminal fluid are unaffected by diet (hay or corn silage) during in the growing period, however switch to a corn-based finishing diet increases the concentration in both locations (6). When switched from a feedlot ration to a forage-based diet, fewer cattle naturally infected with E. coli Ol57:H7 shed the pathogen (18). Some reports indicate that fecal shedding of E. coli can be reduced by feeding forage (1 month) prior to slaughter (20, 7, 18, 10) while other studies have found that fecal shedding of pathogenic bacteria was unaffected (3, 11).

E. coli may be suppressed by specific acids produced when forages (hay, rye grass, silage) are digested (16). Prior to transport for slaughter, feeding pasture-fed cattle forage, rather than fasting, can reduce the risk of carcass contamination with bacteria of digesta or fecal origin. Specific feed components may impact the frequency and magnitude of fecal excretion of E. coli O157:H7. Some phenolic acids found in forage plants can decrease viable counts of E. coli O157:H7 in animals finished on corn (20).

Low numbers of beef cattle shed Salmonella spp. at slaughter (7%). This varies little as a function of the pre-slaughter production system (grass or lot feeding) (11). Feedlot cattle are more likely to have Campylobacter spp. in their intestinal tracts and on their carcasses than are pasture-fed cattle (13). However, post-slaughter carcass chilling reduces the incidence by 10 fold in 20 hr. More rumen (78%) and fecal (94%) samples from pasture fed cattle have been shown to be positive for Campylobacter spp. than those from concentrate (grain) fed cattle (50% rumen, 72% fecal) (17).

This brings us to the second question, “do higher levels of fecal pathogen loads and excretion rates have an effect on the meat derived from their carcasses”?

Muscle tissue is sterile unless it is contaminated by an external source. Livestock hides, which can become a significant source of microbial contamination, can occur at the feedlot, in transport trailers, and in contaminated lairage pens (9). Long transport times and time off feed prior to slaughter also increases hide contamination (2, 3). E. coli and Salmonella spp. transfer onto cattle hides that occurs in the holding environments of U. S beef processing plants accounts for a larger proportion of hide and carcass contamination than does the initial bacterial population found on the cattle exiting the feedlot (1). Hide wash cabinets, carcass trimming, spraying with sanitizers (4), hot-water washing, irradiation, and using dips (14) all reduce microbial load.

Diet per se appears to have some, if small, effects on pathogens in the rumen, gut and feces of cattle. However, once they are slaughtered, whether those bacteria end up on the carcass or on the meat cut from it is largely a function of sanitary practices during transport, lairage, slaughter, chilling, and processing. Therefore, the statement, “Meat from Grass Fed Cattle is Safer than Meat from Cattle that are Corn Fed” is between “Unknown” and “Misguided” because if we don’t have good repeatable scientific evidence that changes in microbe distributions in the rumen, hindgut, feces and hides that result from dietary alterations do, in fact carry over onto the meat, we would be remiss in saying that the diet is the (one and only) cause of the problem.

_References

_{Arthur, TM, Bosilevac, JM, Brichta-Harhay, DM, Kalchayanand, N, King, DA, Shackelford,-SD, Wheeler, TL, Koohmaraie, M. 2008. Source tracking of Escherichia coli O157:H7 and Salmonella contamination in the lairage environment at commercial U.S. beef processing plants and identification of an effective intervention. J. Food Protect. 71(9): 1752-1760}

_{Arthur,TM, Bosilevac, JM, Brichta-Harhay, DM, Guerini, MN, Kalchayanand, N, Shackelford, SD, Wheeler, TL, Koohmaraie, M. 2007. Transportation and lairage environment effects on prevalence, numbers, and diversity of Escherichia coli O157:H7 on hides and carcasses of beef cattle at processing. J. Food Protect. 70(2): 280-286}

_{Beach, JC, Murano, EA, Acuff, GR. 2002. Prevalence of Salmonella and Campylobacter in beef cattle from transport to slaughter. J. Food Protect. 65(11): 1687-1693}

_{Bell, KY, Cutter, CN, Sumner, SS. 1997. Reduction of foodborne micro-organisms on beef carcass tissue using acetic acid, sodium bicarbonate, and hydrogen peroxide spray washes. Food Microbio. 14(5): 439-448}

_{Berg, J, McAllister, T, Bach, S, Stilborn, R, Hancock, D, LeJeune, J. 2004. Escherichia coli O157:H7 excretion by commercial feedlot cattle fed either barley- or corn-based finishing diets. J. Food Protect. 67(4): 666-671}

_{Berry, ED, Wells, JE, Archibeque, SL, Ferrell, CL, Freetly, HC, Miller,DN. 2006. Influence of genotype and diet on steer performance, manure odor, and carriage of pathogenic and other fecal bacteria. II. Pathogenic and other fecal bacteria. J. An. Sci. 84(9): 2523-2532}

_{Callaway, TR, Elder, RO, Keen, JE, Anderson, RC, Nisbet, DJ 2003. Forage feeding to reduce preharvest Escherichia coli populations in cattle, a review. J. Dairy Sci. 86(3): 852-860}

_{Depenbusch, BE, Nagaraja, TG, Sargeant, JM, Drouillard, JS, Loe, ER, Corrigan, ME. 2008. Influence of processed grains on fecal pH, starch concentration, and shedding of Escherichia coli O157 in feedlot cattle. J. An. Sci. 86(3): 632-639}

_{Dewell, GA, Simpson, CA, Dewell,RD, Hyatt, DR, Belk, KE, Scanga, JA, Morley, PS; Grandin,-T; Smith,-GC; Dargatz,-DA; Wagner,-BA; Salman,-MD. 2008. Risk associated with transportation and lairage on hide contamination with Salmonella enterica in finished beef cattle at slaughter. J. Food Protect. 71(11): 2228-2232}

_{Diez-Gonzalez, F, Callaway, TR, Kizoulis, MG, Russell, JB . 1998. Grain feeding and the dissemination of acid-resistant Escherichia coli from cattle. Sci. 281(5383), 1666-166}

_{Fegan, N, Vanderlinde, P, Higgs, G, Desmarchelier, P. 2004. Quantification and prevalence of Salmonella in beef cattle presenting at slaughter. J. App. Microbio. 97(5), 892-89}

_{Gilbert, RA, Denman, SE, Padmanabha, J, Fegan, N, Al-Ajmi, D, McSweeney, CS. 2008. Effect of diet on the concentration of complex Shiga toxin-producing Escherichia coli and EHEC virulence genes in bovine faeces, hide and carcass. Internat. J. Food Microbio.. 121(2): 208-216}

_{Grau, FH. 2008. Campylobacter jejuni and Campylobacter hyointestinalis in the intestinal tract and on the carcasses of calves and cattle. J. Food Protect. 51(11) p. 857-861}

_{Hussein, H S, Lake, SL, Ringkob, TP. 2001. Cattle as a reservoir of Shiga-like toxin-producing Escherichia coli including O157:H7 – pre- and post-harvest control measures to assure beef safety. Prof. An. Sci. 17(1), 1-16}

_{Hutchison, ML, Walters, LD, Avery, SM, Munro, F, Moore, A. 2005. Analyses of livestock production, waste storage, and pathogen levels and prevalences in farm manures. App. Environ. Microbiol. 71(3): 1231-1236}

_{Jacobson, LH, Nagle, TA, Gregory, NG, Bell, RG, Le-Roux, G, Haines, JM. 2002. Effect of feeding pasture-finished cattle different conserved forages on Escherichia coli in the rumen and faeces. Meat Sci. 62(1): 93-106}

_{Krueger, NA, Anderson, RC, Krueger, WK, Horne, WJ, Riley, DG, Loneragan,GH, Phillips,WA, Gray, JT, Fedorka-Cray, PJ. 2008. Fecal shedding of foodborne pathogens by Florida-born heifers and steers in U.S. beef production segments. J. Food Protect. 71(4): 807-81}

_{Russell, JB, Diez-Gonzalez, F, Jarvis, GN. 2000. Invited review: effects of diet shifts on Escherichia coli in cattle. J. Dairy Sci. 83(4): 863-873}

_{Wesley, IV, Callaway,TR, Edrington, TS, Carstens, GE, Harvey,RB, Nisbet, DJ. 2008. Prevalence and concentration of Campylobacter in rumen contents and feces in pasture and feedlot-fed cattle. Foodborne Path. Disease. 5(5): 571-577}

_{Wells,JE, Berry,ED, Varel,VH, 2005. Effects of common forage phenolic acids on Escherichia coli O157:H7 viability in bovine feces. App. Environ. Microbiol. 71(12): 7974-7979}

Introduction
The global population is predicted to increase to 9.5 billion people in the year 2050 (U.S. Census Bureau, 2008). This is predicted to increase total food requirements by 100% (Tilman et al., 2002) and will be further complicated by demand for milk and meat protein as formerly-low-income populations become more affluent (Keyzer et al., 2005). The challenge to the beef industry is to reconcile the need for sufficient safe, affordable, high-quality meat for the growing population, with consumer quality and safety perceptions related to different feeding or production systems.

The US beef production cycle
The majority of US beef systems can be summarized into three stages: 1) cow-calf operations where calves are born, suckle and graze until weaning at 6-10 months old; 2) weanling/stocker operations where animals graze until 12-18 months of age and; 3) feedlots where stock are group-housed and fed a corn-based diet until slaughter (18-22 months; IBISWorld, 2009). Most of a ‘corn-fed’ animal’s life is therefore spent grazing on pasture: high-corn diets are only fed in the final finishing period to ensure animals meet processor weight and condition specifications. Feedlots have been a major contributor to increased production efficiency over the past 30 years: in 1975, 24.0 billion lb of beef was produced in 1975 from 40.9 million beef animals (USDA, 1976), compared to 26.7 billion lb from 34.5 million head in 2008 (USDA, 2009). This is equivalent to an extra 187 lb of beef being produced per animal.

The term ‘grass-fed’ is used to refer to cattle that are finished by grazing on pasture. The USDA certification process for grass-fed livestock specifies that animals must be fed only grass and forage after weaning, with no grain or grain byproducts in the diet (USDA/AMS, 2007). Nonetheless, it is important to note that unlike organic certification, this process is strictly voluntary and any producer may label their product as ‘grass-fed’ without third-party verification. Furthermore, ‘grass-fed’ certification does not contain any provision re: the use of antimicrobials or hormones. Therefore although the label may imply a quality attribute for the product, it refers only to feeding practices and should not be considered as a guarantee of other management, safety or quality considerations. Grass-fed beef systems are demonstrably less efficient than conventional production, with greater resource use and environmental impact per pound of beef produced (Avery and Avery, 2008). Although grass-fed beef often commands a premium price for the producer, this may be beyond the purchasing capacity of many consumers; therefore the economic and social sustainability of the system is questionable.

Beef product safety
The USDA Food Safety and Inspection Service (FSIS; http://www.fsis.usda.gov/) acts to ensure a safe and wholesome US meat supply via a variety of regulations, policies and inspection programs. Nonetheless, media coverage of potential human health risks associated with beef, combined with readily-available (but not necessarily scientifically-verified) information from the internet, may lead to its safety being questioned by the consumer.

Beef product safety was seriously questioned by the consumer after a link was discovered between the UK outbreak of bovine spongiform encephalopathy (BSE) and the incidence of variant Creutzfeldt–Jakob (vCJD) disease in humans. This led to consumer concern that was exacerbated further when the first US BSE case was noted in 2003 (CDC, 2008). Nonetheless, removing animal protein from ruminant diets, surveillance testing and policies to prevent at-risk cattle from entering the human food chain have prevented BSE from becoming endemic in the USA (CDC, 2008) and the risk of contracting vCJD from US beef, regardless of production system, is extremely low (Donnelly, 2004).

Aggressive publicity campaigns by activist groups opposed to conventional agriculture have led to feedlots being labeled as ‘factory farms’ (Nierenberg, 2005), claiming that corn-fed beef is not ‘natural’ (Pollan, 2006) and may threaten human health (O’Brien, 2001). This leads to the misconception that foodborne diseases are the prevalence of feedlots alone and that meat from grass-fed animals is intrinsically safe. For example, the bacteria E. coli 0157:H7 is found naturally in animal and human intestines, but via ingestion of insufficiently-cooked contaminated meat, is responsible for ~73,000 cases of foodborne disease per year (Mead et al., 1999). Indeed, E. coli 0157:H7 contamination led to the recall of 21.7 million lb of beef in 2007 (USDA, 2007). Contamination of meat by intestinal contents or fecal matter at slaughter is a major factor in E. coli 0157:H7 transmission (National Academy of Sciences, 2002), but this risk is reduced to almost zero by effective slaughterhouse management policies (Bacon et al., 2000). Despite activists’ claims, studies show similar prevalence of E. coli 0157:H7 between pasture and feedlot systems (Renter et al., 2004; Rasmussen & Casey, 2001) and there is no scientific evidence to suggest that beef from grass-fed cattle may be microbiologically safer than from cattle that are fed corn.

Absence claims (e.g. ‘no hormones’, ‘no antibiotics’) are increasingly used as marketing tools within the livestock industry to differentiate between nutritionally-identical products. Two classes of pharmaceuticals used in beef production are highlighted as areas of consumer concern: antimicrobials and hormones (Brewer & Rojas, 2008). Antimicrobials are used within the beef production system for therapeutic and feed additive purposes. Animal welfare is paramount within animal agriculture; therefore rigorously-tested therapeutic drugs approved by the U.S. Food and Drug Administration (FDA) are used to treat disease in both corn- and grass-fed beef animals (FDA/CVM, 2000). Use of therapeutic antimicrobials only when necessary and under the guidance of a veterinarian, ensures optimum animal health, welfare and the production of safe food for human consumption. Feed antimicrobials improve the efficiency by which feed is converted into weight gain, thus reducing resource use (NRC, 1999). The majority (83%) of feedlots added antimicrobial drugs to feed or water in 1999 (USDA, 2000) and although similar data is not available for pasture-based systems, the ‘grass-fed’ label does not automatically infer their absence. Nevertheless, bacterial resistance to antimicrobial drugs is a growing concern. The FDA (2000) considers the sporadic nature of therapeutic drug use unlikely to contribute to antimicrobial resistance; but, following a European ban on feed antimicrobial use in swine and poultry, evidence suggests that these drugs may also be removed from US production systems in future (Fajt, 2007). One often-repeated myth is that antimicrobials from feedlot systems are concentrated in meat, whereas grass-fed beef is ‘natural’ and therefore healthy. Regardless of feeding system, strict regulations govern the minimum time period that must elapse between therapeutic and feed antimicrobial use and slaughter to prevent antimicrobial residues being in meat. Products that exceed residue limits do not enter the food supply and confer significant financial penalties to the producer (FSIS, 2008). Despite marketing claims by individual producers, there is no scientific evidence to suggest that antimicrobial use differs between corn-fed or grass-fed systems, and the regulatory, monitoring and testing procedures in place ensure that beef products from all systems are safe for human consumption.

Growth-promoting steroid hormones are integral to US beef production, facilitating increased meat production using fewer resources and with a lower environmental impact (Avery & Avery, 2007). A constant supply of hormones is provided by a subcutaneous implant in the ear, which is discarded at slaughter (Preston, 1999). Despite the rigorous animal and human safety certification programs in place, some organizations suggest that supplemental hormones given to beef animals may lead to undesirable human health effects including early puberty and cancer (Balter, 1999). However, the hormones used in implants are natural or synthetic equivalents of steroids naturally produced by the animal and the quantities found in meat are extremely low (Preston, 1999). For example, an individual would have to consume >13 lb of beef from an implanted steer to equal the amount of estradiol naturally found in a single egg (Foreign Agricultural Service, 1999). As with antimicrobial drugs, the ‘grass-fed’ label is no indication of whether growth-promoting hormones are used in a beef production system and there is no published scientific data to imply a difference in hormone use between pasture and corn-based feeding systems.

Conclusion
Opportunities exist for all food production systems within US agriculture and individual producers may gain economic benefits from niche marketing strategies. However, the safety and quality of all beef products is assured by federal regulatory, monitoring and testing procedures, therefore marketing claims solely relating to feeding practices should not be considered to confer any quality or safety benefits above other production systems.

_{References
Avery, A. and D. Avery (2007) The Environmental Safety and Benefits of Pharmaceutical Technologies in Beef Production. Hudson Institute, Center for Global Food Issues, Washington, DC.
Bacon, R. T., K. E. Belk, J. N. Sofos and G. C. Smith (2000) Executive summary: Incidence of Escherichia coli O157:H7 on hide, carcass and beef trimmings samples collected from United States packing plants. 53rd Annual Reciprocal Meat Conference, Ohio State University, Columbus, OH.
Balter, M. (1999) Scientific cross-claims fly in continuing beef war. Science 284:1453-1455.
Brewer, M. S. and M. Rojas (2008) Consumer attitudes towards issues in food safety J. Food Saf. 28:1-22.
CDC (2008) BSE (Bovine Spongiform Encephalopathy, or Mad Cow Disease)http://www.cdc.gov/ncidod/dvrd/bse/
Donnelly, C. A. (2004) Bovine Spongiform Encephalopathy in the United States — An Epidemiologist’s View. New Enlg. J. Med. 350:539-542.
Fajt, V. R. (2007) Regulation of drugs used in feedlot diets. Vet. Clin. North Am. 23:299-307.
FDA (2000). HHS Response to House Report 106-157- Agriculture, Rural Development, Food and Drug Administration, and Related Agencies, Appropriations Bill, 2000. Human-Use Antibiotics in Livestock Production. U.S. FDA, Washington, DC.
FDA/CVM (2000) Judicious Use of Antimicrobials for Beef Cattle Veterinarians. FDA/CVM, Washington, DC.
FSIS (2008) 2008 FSIS National Residue Program Scheduled Sampling Plans. USDA/FSIS, Washington, DC
Foreign Agricultural Service (1999) A Primer on Beef Hormones.http://stockholm.usembassy.gov/Agriculture/hormone.html
IbisWorld (2009) Beef Cattle Production in the US #11211. IBISWorld, Santa Monica, CA.
Keyzer, M. A., M. D. Merbis, I. F. P. W. Pavel, and C. F. A. van Wesenbeeck (2005) Diet shifts towards meat and the effects on cereal use: can we feed the animals in 2030? Ecological Economics 55:187-202.
Mead, P. S., L. Slutsker, V. Dietz, L. F. McCaig, J. S. Bresee, C. Shapiro, P. M. Griffin, and R. V. Tauxe (1999) Food-Related Illness and Death in the United States. Centers for Disease Control and Prevention, Atlanta, GA.
National Academy of Sciences (2002) Escherichia coli O157:H7 in Ground Beef: Review of a Draft Risk Assessment. Committee on the Review of the USDA E. coli O157:H7, Farm-to-Table Process Risk Assessment, Washington, DC.
Nierenberg, D. (2005) Happier Meals: Rethinking the Global Meat Industry. Worldwatch paper # 171. Worldwatch Institute.http://www.wellfedworld.org/PDF/WorldWatch%20Happier%20Meals.pdf
NRC (1999) The Use of Drugs in Food Animals: Benefits and Risks. National Academy Press, Washington, DC.
O’Brien, T. (2001) Factory farms and human health. The Ecologist. 31:5 30-34, 58-59.
Pollan, M. (2006) The Omnivore’s Dilemma. The Penguin Group (USA) Inc, New York, NY.
Preston, R. L. (1999) Hormone containing growth promoting implants in farmed livestock. Adv. Drug Del. Rev. 38:123-138.
Rasmussen, M. A. and T. A. Casey (2001) Environmental and food safety aspects of Escherichia coli O157:H7 infections in cattle. Crit. Rev. Microbiol. 27:57-73.
Renter, D. G., J. M. Sargeant and L. L. Hungerford (2004) Distribution of Escherichia coli O157:H7 within and among cattle operations in pasture-based agricultural areas. Am. J. Vet. Res. 65:1367-1376.
Tilman, D., K. G. Cassman, P. A. Matson, R. Naylor and S. Polasky (2002) Agricultural sustainability and intensive production practices. Nature 418:671-677
U.S. Census Bureau (2008) Total Midyear Population for the World: 1950-2050.http://www.census.gov/ipc/www/idb/worldpop.html
USDA (1976) Livestock Slaughter Annual Summary 1975. USDA, Washington DC.
USDA (2000) Part III: Health Management and Biosecurity in U.S. Feedlots, 1999. USDA/APHIS/NAHMS, Fort Collins, CO.
USDA (2007) New Jersey Firm Expands Recall of Ground Beef Products due to Possible E. coli 0157:H7 Contamination.http://www.fsis.usda.gov/pdf/recall_040_2007_exp_update.pdf
USDA (2009) Data and Statistics.http://www.nass.usda.gov/Data_and_Statistics/Quick_Stats/index.asp
USDA/AMS (2007) United States Standards for Livestock and Meat Marketing Claims, Grass (Forage) Fed Claim for Ruminant Livestock and the Meat Products Derived From Such Livestock. Docket # AMS–LS–07–0113;LS–05–09. USDA/AMS, Washington, DC.}

Introduction: What do we mean by safe?
To begin this discussion, we need to understand what “safe” really means. From the standpoint of meat and poultry products, the U.S. Department of Agriculture, Food Safety Inspection Service (USDA-FSIS) classifies hazards as either physical, chemical or biological. The risks associated with either physical or chemical hazards in live cattle are primarily related to animal husbandry practices, and are generally unrelated to the diet of the animals. There is nothing inherent in the production of either grass or grain fed cattle that would be likely to change the risk associated with either physical or chemical hazards. This leaves biological hazards, which in the United States are commonly thought of as bacterial contaminants. These would include various species of Salmonella and the pathogenic Escherichia coli species, especially E. coli O157:H7. This document will focus exclusively on the potential differences in biological hazards between grass fed and grain fed cattle.

What the Science says: Live Animal
Live cattle may harbor E. coli O157:H7 with no external signs of illness. This makes detection in the live animal difficult, as the bacterium may be not only in the intestinal tract and feces, but also on the hide, hair and hooves of the animal. Since the early 1990â€s there has been a growing body of scientific evidence on the impact of cattle diets on the presence of bacteria of public health significance in or on the live animal. In particular, feeding large amounts of corn has been reported to increase the populations of Escherichia coli (both pathogenic and non-pathogenic) in the cowâ€s digestive tract. These bacteria are also more resistant to acid conditions. Switching the diet of the live cow from grain to grass has been reported to result in a decrease in the overall population as well as a decrease in the acid resistance of the E. coli population.
When humans consume food, the food collects in the gastric fluid in the stomach, which is very acidic. This exposure to acid may kill many potential human pathogens, preventing the human host from becoming ill. Increasing the acid resistance of any group of bacteria may increase the probability of survival, and therefore the likelihood that the human host may become ill. It is biologically plausible that bacteria which are more acid-tolerant may be more likely to survive passage through the stomach and therefore be more likely to cause illness in humans. However, many enteric bacteria have a natural occurring acid tolerance response which allows significant numbers of bacteria to survive exposure to the low pH of gastric fluid. E. coli O157:H7 in particular has a very low infectious dose for humans, which suggests that it has the innate mechanisms to survive passage through the human stomach already, without any increase in acid resistance.

What the Science says: Processing
E. coli O157:H7 follows a seasonal pattern both in terms of occurrence on cattle and in numbers of human illnesses, with the peak times for both during the summer months. In some studies, up to 75% of the cattle entering slaughter establishments have been reported to carry E. coli O157:H7 on their hides. However, in those same studies, the bacterium is rarely isolated from the finished carcasses in the holding coolers. This is directly attributable to the hygienic slaughter and dressing of the carcasses, as well as the widespread use of a variety of antimicrobial interventions, which have been developed over the last twenty years. In addition, the USDA-FSIS made a substantial change in the meat inspection regulations in 1996, with the focus of inspection now on the prevention of contamination during processing.
E. coli O157:H7 does not infect cattle in the sense that it does not enter the edible muscle tissue. It is confined to the gastro-intestinal tract or the external surface of the animal, and contamination occurs as accidental contact between the hide or intestinal contents with the edible muscle tissue. Modern slaughter establishments focus on reducing microbial contamination by both physical means (avoidance of contamination) and direct interventions. Although no system is perfect, as evidenced by the continuing recalls and human illnesses linked to meat, it is overall remarkably effective in controlling contamination in an industry that slaughters over 30 million cattle every year.

What are the practical implications:
The science suggests that cattle fed grass in place of grain may have lower populations of E. coli in their intestinal contents and that these bacteria may be less resistant to acid. However, whether these lower numbers of E. coli relate to less contamination of beef carcasses is at best hypothetical. In spite of popular opinion, contamination of beef carcasses with bacteria of public health significance is a relatively rare occurrence, although it is certainly regrettable when it occurs. Whether an increase in acid resistance of E. coli O157:H7 results in a greater risk of infection would appear unlikely, as naturally occurring E. coli O157:H7 already seem to possess the mechanisms necessary to survive passage through the human stomach.

Is meat from grass-fed cattle is safer than meat from cattle that are fed corn?

Probably not from a biological point of view. The practical implications of lower E. coli populations to carcass contamination have not been demonstrated, and it is unlikely that an increase in acid resistance will materially affect the number of human infections from E. coli O157:H7.

No matter which diet the animals are fed, there is still the need for the consumer to exercise reasonable care in handling any raw foods. Much like driving an automobile where the driver takes reasonable precautions, such as wearing a seat belt and driving defensively, consumers need to handle and cook food safely. The USDA-FSIS has many consumer resources for handling and cooking foods, but the pamphlet “Basics for handling food safely” probably summarizes these practices best. The basics are:

• Clean – Wash hands and surfaces often
• Separate – Keep raw and cooked foods separate
• Cook – Cook to proper temperatures
• Chill – Refrigerate foods promptly

_References

_{Arthur, T.M., J. M. Bosilevac, X. Nou, S. D. Shackelford, T. L. Wheeler, M. P. Kent, D. Jaroni, B. Pauling, D. M. Allen, and M. Koohmaraie. 2004. Escherichia coli O157 Prevalence and Enumeration of Aerobic Bacteria, Enterobacteriaceae, and Escherichia coli O157 at Various Steps in Commercial Beef Processing Plants. J. Food Protect. 67: 658–665}

_{Diez-Gonzalez, F., T. R. Callaway, M. G. Kizoulis, J. B. Russell 1998. Grain Feeding and the Dissemination of Acid-Resistant Escherichia coli from Cattle. Science 281, 1666-1668.}

_{Martz, F. 2000. Pasture-based finishing of cattle and eating quality of beef.
http://aes.missouri.edu/fsrc/research/pasture.stm (accessed 21 May 2009)}

_{Russell, J.B. F. Diez-Gonzalez and G.N. Jarvis. 2000. Potential effect of cattle diets on the transmission of pathogenic Escherichia coli to humans. Microbes and Infection, 2: 45−53.}

_{U.S. Department of Agriculture – Food Safety and Inspection Service. 2009. Safe Food Handling.http://www.fsis.usda.gov/factsheets/Safe_Food_Handling_Fact_Sheets/index.asp(accessed 21 May 2009)}

_{U.S. Department of Agriculture – Food Safety and Inspection Service. 2009. Basics for handling food safely.
http://www.fsis.usda.gov/PDF/Basics_for_Safe_Food_Handling.pdf (accessed 21 May 2009)}