Case Study: What’s in Livestock Feed?
In recent years, livestock producers, and consumers have become
concerned about some of the substances that are added to livestock
feed. These include hormones, antibiotics, and animal by-products. Each
of these substances is associated with its own set of concerns.
Raising large numbers of animals in a confined space can allow for
spread of disease among livestock. To combat this, low levels of
antibiotics are added to animals feed on a long-term basis. The
widespread use of antibiotics in livestock operations has contributed to many pathogens becoming resistance to
antibiotics. Studies conducted by Health Canada have shown that antibiotic resistance strains of bacteria, including
salmonella, commonly occur in Canadian livestock. The constant use of antibiotics on livestock can also make pathogens
more resistance to antibiotics that are used to treat human illnesses. This has made it difficult for some types of illnesses
to be treated in humans.
Another substance added to livestock feed is growth hormones. Growth hormones help animals grow faster so they can
be sold sooner. Some types of growth hormones increase lean tissue growth and reduce fat. This results in a healthier
product that is sold at a lower cost to the consumer. Concerns about the use of hormones in livestock are related to
their impact on human health and whether they may be a cause of cancer.
Between 1993 and 2010, almost 200 000 cases of bovine spongiform encephalopathy (BSE) were confirmed in the
United Kingdom. BSE, also referred to as “mad cow disease” is caused by mutated protein that damages the central
nervous system of cows and eventually kills them. The likely source was cattle feed that contained animal by-products
infected with BSE. There is strong evidence that the consumption of meat containing the protein that cases BSE cause a
similar neurological disease in humans called Creutzfeldt-Jakob disease (CJD). As a result of the BSE outbreak in the
United Kingdom and the effect it had on human health, Canada updated laws concerning animal feed in 2007. The
updated law prohibits most proteins, including those potentially infected with BSE, from all animal feed, pet foods, and
fertilizers.
(http://www.cdc.gov/ncidod/dvrd/bse/)
Jackson , Ann, Ellen Murray , et al, et al. Environmental Science: A Canadian Perspective. 1. Whitby: McGraw-Hill Ryerson, 2013. Print.
Research and Analyze
1. Research more about the long term effects the use of antibiotics in animal feed has on human health. What
significance of antibiotics resistance strains of bacteria to human health? How important is the issue to public
health? Is it possible to raise livestock without antibiotics and still make a profit? How?
2. Is there a correlation between the use of growth hormones in beef and dairy cattle and cancer in humans? Do
research and summarize.
3. Research more about the use of animal by-products in livestock feed and the incidence of BSE and CJD. Why
should people be concerned about this issue? Do you think the updated laws will protect cattle and humans
from becoming infected with the proteins that cause BSE and CJD? Why or why not?
Communicate
1. Choose one of the issues you researched and design an information campaign about it. Include the facts about
the issues, as well as your opinion about its importance and solutions to the problem.
Jackson , Ann, Ellen Murray , et al, et al. Environmental Science: A Canadian Perspective. 1. Whitby: McGraw-Hill Ryerson, 2013. Print.