news center

Thin time for pigs

Thin time for pigs

作者:强醒  时间:2019-03-07 05:01:00  人气:

By Jon Sutton OUR preference for lean meat is making more and more pigs anorexic. Veterinary scientists say thin sow syndrome, as the illness is known, is an emerging animal welfare problem. But studying the illness could speed up the search for drugs to treat human eating disorders. Farmers use selective breeding to produce animals that are muscular and lean. John Owen of the University of Wales in Bangor says these programmes can produce pigs prone to symptoms that resemble anorexia nervosa in people. The pigs affected are usually young females. They don’t eat enough to maintain their body weight, are hyperactive and may not go on heat. The syndrome hasn’t been widely studied, but Owen reviews research into the condition in the latest Nutrition (vol 15, p 609). “This selective breeding has led to the uncovering of recessive genetic traits which produce extremes,” says Owen. It seems that the pigs have mutations in a gene for the ryanodine receptor, which regulates the flow of calcium ions across cell membranes. These mutations are linked to leanness and susceptibility to stress. So far, only a small percentage of pigs seem to be affected. But some researchers suspect the condition is becoming more common. “It may well be that Owen has picked up on something that is going to be an increasing problem,” says Donald Broom of the University of Cambridge, a member of the Farm Animal Welfare Council that advises Britain’s Ministry of Agriculture, Fisheries and Food. Experts in human eating disorders are intrigued. Because pigs have similar body weights and digestive systems to people, they may provide valuable insights into these diseases. Nicky Bryant of the Eating Disorders Association in Norwich says that human eating disorders also have a genetic component: epidemiological studies suggest that some people are predisposed to suffer from them. “However, there are also other environmental triggers such as low self-esteem and bullying that might not have an equivalent in the animals,” she says. Some scientists think the parallels are even closer. Jane Guise, director of Cambac JMA Research, an independent veterinary science institute based in Chippenham, Wiltshire, notes that changes in pig housing on British farms, introduced to improve animal welfare, may have provided an environmental trigger that has made the problem worse. Since January, farmers have been banned from tethering pigs in individual stalls. But in group housing, where animals compete for access to the trough, thin sows are even less likely to get enough to eat. “It’s time for human and veterinary scientists to start working a lot more closely,” says Guise. Researchers could use the skinny pigs as a way of testing new drugs to treat anorexia. Anorexic pigs have already been treated experimentally by giving a drug that raises levels of the neurotransmitter serotonin in the brain. Similar drugs also seem to help some people with anorexia. “There is no doubt at all that animal models will prove to be very useful,” says Janet Treasure of the Institute of Psychiatry in London,