Besides the addition of antimicrobials to promote growth, animal feed is also routinely spiked with hormonal growth promoters of which some may be carcinogenic. Hormone residues that have been isolated from beef include trenbolone acetate, zeranol and stilbene diethylstilboestrol (DES), oestradiol, dienoestrol, hexaestrol, 17α-ethynyloestradiol, ketosteroids, testosterone, progesterone and progesterone acetate, which are all used as anabolic steroids to promote weight increase. To promote lean meat production, animals are fed β-agonists, a group of drugs that convert fats to fatty acids and stimulate the formation of proteins, to promote rapid weight gain. In addition in some countries growth hormone is administered and even genetically-engineered hormones are used, such as PST, which is used
to promote lean meat production in pigs. Some of these growth promoters, such as clenbuterol, are banned, but there is a healthy black market trade in these growth-promoting drugs as shown by the clenbuterol scandal in 1996 when German authorities found that the drug was being used on more than 40 calf fattening farms in Nordrhein-Westfalen and consequently prohibited the slaughter of 2400 calves and arrested a veterinary drug dealer. In a further case around the county of Gütersloh, calves were found with the banned antibiotic Chloramphenicol.82
Farm animals today are often treated as commodities, like inanimate consumer goods. They are frequently housed in unhealthy environments and fed virtually anything that will promote growth and increase profits, even though the long-term effect on the health of the animals or the human consumer is not known. In large chicken hatcheries the chicks never see sunlight, but are subjected to low-intensity light for close on 24 hours per day. The lights are switched off only for approximately 15 min each day so that the chickens can get used to darkness, lest they panic during a power failure and cause production losses. Animals are cramped together to limit their movements and energy expenditure, because growth and mass increase are the paramount criteria that are taken into account when designing these facilities. New breeds of chickens are selected for growth performance with virtual disregard for all other parameters. In the past, a free range chicken could be assumed to consume approximately 17kg of feed to grow to a market mass of 1.5kg. Today, some breeds utilise only 3.5kg to achieve the same mass increase, and this in only six weeks. The chickens are geared for rapid growth, but their other systems are severely compromised. The cardiovascular system, internal organs and immune systems are poorly developed so that extreme care must be taken not to induce stress or exposure to infectious bacteria lest they die before reaching market size.
Farm animals are fed carcass meal, fish meal, edible plastic, sewage, petro-chemical residues and excrement. On some farms veritable food chains have been set up where chicken manure, from battery chickens, is fed to the sheep and cattle, and dead chicks and unhatched eggs in turn are the feed items used in the piggery. In the chicken industry, the slaughter offal such as entrails, legs and heads are often dried, ground and recycled as feed , thus effectively turning the chickens into cannibals. Moreover, the chickens are routinely manipulated with a host of growth stimulating, antimicrobial and digestibility enhancing drugs.