Objections to the use of animal products

Objections to the use of animals to provide human food are also made on environmental grounds. Overgrazing can destroy plant communities, demand for additional grazing can cause deforestation, the excreta of intensively kept livestock cause pollution problems, and methane from ruminants contributes to global warming. These raise complex issues that cannot be explored fully in this book. 

The direct nutritional objections to animal-derived foods arise mainly from two sources. First, farm animals may harbour organisms such as pathogenic bacteria and intestinal parasites that may be transmissible to man through the consumption of animal products. Second, some of the supposedly valuable nutrients in animal products - fats, in particular - have been implicated in the causation of certain diseases of man. 

The Merck Veterinary Manual lists 150 diseases transmissible from animals to man (known collectively as zoonoses), but the majority of these are transferred by contact or bites or are carried by wild animals. The food-borne diseases of man that arise from farm animals form a relatively small, but nevertheless important, group and are summarised in Box 25.2. The infection of man with these diseases can be minimised by various means, the first of which involves their restriction in, or 

Antibiotics in feeds (see Chapter 24) have been used in intensive livestock systems to restrict infections, but their routine administration is now prohibited or discouraged because of the danger of producing antibiotic-resistant organisms. 

Of the diseases hsted, those regarded today as being the most important in developed countries are the enteric infections from Campylobacter, E. coli and Salmonella organisms. Although cases of food poisoning have always occurred, people today are now less tolerant of them, both mentally (food is expected to be safe) and perhaps physically (as a generally cleaner environment has prevented the development of resistance to the organisms responsible). 

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The most serious objections to the presence of drug residues in food intended for human consumption arise as a consequence of human health considerations. With tire extensive use of drugs in animal production, residues of the parent drugs and/or metabolites have a high potential to be present in the edible animal products. The public health significance of such adulteration of the food supply is determined mainly by the level of the residues and the individual drugs they are originated from. 

The legal controls on animal testing were introduced at the European level by a Directive in 1986. The central objectives cited in the formulation of the controls were to avoid disparities in the controls applied across Member States that might affect the functioning of the common market, and also to limit to a minimum the number of animals used in product development whose use was necessary to meet testing requirements, and to ensure, as far as possible, the best care and treatment of the animals during the conduct of the research and in the method of their disposal. 

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