Genetically engineered livestock is expected to revolutionize the agricultural industry. It is envisaged that animals can be made to grow faster and to incorporate changes in fat composition so as to be more suitable for human dietary needs. Gene transfers have been carried out on laboratory animals, but have also recently been extended to domestic animals. Most studies have centred around growth-regulation, as studies in mice have shown that gene transfers of bovine, ovine, rat or human growth-hormone genes can almost double the rate of growth in mice. Transgenic farm animals already include chickens, cows, pigs, sheep, rabbits and fish. Human, Bovine and rat growth-hormone genes have been transferred to pigs, but the mortality rates in these animals is high. Leaner meat has been produced in transgenic pigs, but at a price.
Transgenic animals suffer from a variety of pathological changes which shorten their lifespan. In pigs it was found that the animals were lethargic, and suffered from lameness, uncoordinated gait, protruding eyeballs and thickened skin. Moreover, they suffered from gastric ulceration, severe synovitis, degenerative joint disease, pericarditis and endocarditis, cardiomegaly, parakeratosis, nephritis and pneumonia.102 The risk of disease from contaminated animal products today is indeed something to consider. In the past the major concerns revolved around infectious diseases and parasitic and viral infections. This risk still exists today, but additional risk factors have been added through modern animal husbandry.
Modern technology has also had its effect on plant foods, with gene transfers being currently in vogue. The long term effects of these manipulations are also not known and these products may also be viewed with some degree of scepticism. However, man has to eat, and if a choice has to be made between manipulated plant or animal foods, the consumption of plant foods would certainly be associated with lower risks of contracting diseases. A diet free from animal products, and concentrating on a variety of fresh whole foods will supply excellent nutrition and will at the same time protect against many of the modern ills associated with Western diets. Such a diet need not, and indeed should not, be less attractive than a diet based on animal products. A little ingenuity with emphasis on variety will provide an exciting, healthy lifestyle.