Academic journal article Environmental Health Perspectives

What Do We Feed to Food-Production Animals? A Review of Animal Feed Ingredients and Their Potential Impacts on Human Health

Academic journal article Environmental Health Perspectives

What Do We Feed to Food-Production Animals? A Review of Animal Feed Ingredients and Their Potential Impacts on Human Health

Article excerpt

OBJECTIVE: Animal feeding practices in the United States have changed considerably over the past century. As large-scale, concentrated production methods have become the predominant model for animal husbandry, animal feeds have been modified to include ingredients ranging from rendered animals and animal waste to antibiotics and organoarsenicals. In this article we review current U.S. animal feeding practices and etiologic agents that have been detected in animal feed. Evidence that current feeding practices may lead to adverse human health impacts is also evaluated.

DATA SOURCES: We reviewed published veterinary and human-health literature regarding animal feeding practices, etiologic agents present in feed, and human health effects along with proceedings from animal feed workshops.

DATA EXTRACTION: Data were extracted from peer-reviewed articles and books identified using PubMed, Agricola, U.S. Department of Agriculture, Food and Drug Administration, and Centers for Disease Control and Prevention databases.

DATA SYNTHESIS: Findings emphasize that current animal feeding practices can result in the presence of bacteria, antibiotic-resistant bacteria, prions, arsenicals, and dioxins in feed and animal-based food products. Despite a range of potential human health impacts that could ensue, there are significant data gaps that prevent comprehensive assessments of human health risks associated with animal feed. Limited data are collected at the federal or state level concerning the amounts of specific ingredients used in animal feed, and there are insufficient surveillance systems to monitor etiologic agents "from farm to fork."

CONCLUSIONS: Increased funding for integrated veterinary and human health surveillance systems and increased collaboration among feed professionals, animal producers, and veterinary and public health officials is necessary to effectively address these issues.

KEY WORDS: animal feed, animal waste, concentrated animal feeding operations, fats, human health effects, nontherapeutic antibiotics, rendered animals, roxarsone, zoonoses. Environ Health Perspect 115:663-670 (2007). doi:10.1289/ehp.9760 available via http://dx.doi.org/ [Online 8 February 2007]

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Animal-based food products derived from cattle, swine, sheep, poultry, and farmed fish constitute a significant portion of the current U.S. diet. In 2003, the U.S. per capita consumption of total meats (including beef, pork, veal, lamb, poultry, fish, and shellfish) was 90.5 kg/year [U.S. Department of Agriculture (USDA) 2005a]. Data from animal-production researchers demonstrate that the quality of these products is directly related to animal feeding practices (Capucille et al. 2004; Gatlin et al. 2003; Zaghini et al. 2005). Therefore, given the high consumption of animal-based food products in the United States, the ingredients used in animal feed are fundamentally important in terms of both the quality of the resulting food products and the potential human health impacts associated with the animal-based food-production chain.

In the early 1900s, animals produced for food in the United States were raised on small family farms where cows predominantly grazed on pasture and young chickens were fed primarily a corn-based diet (Erf 1907). However, in the past 60 years, farms and animal feed formulations have undergone significant changes. Small family-owned and -operated farms have been replaced almost entirely by a system of large-scale operations where individual farmers contract with vertically integrated corporations. High rates of food production have been achieved through these systems in which the scale of operations requires the high throughput generation of animals for processing. Animals are raised in confinement and fed defined feeds that are formulated to increase growth rates and feed-conversion efficiencies. These present day animal feeds contain mixtures of plant-based products, as well as other ingredients ranging from rendered animals and animal waste to antibiotics and organoarsenicals. …

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