Genetic Engineering of Livestock

TLDR

Genetic engineering of livestock is expected to majorly affect agriculture, yet assessing transgene consequences requires multigenerational studies, and achieving pigs with only beneficial growth‑promoting effects may need better control, different genetics, or modified husbandry. The study aimed to systematically evaluate the long‑term effects of elevated bovine growth hormone (bGH) levels in transgenic pigs. Researchers used two lines of transgenic pigs to assess the consequences of sustained bGH elevation over successive generations. Two generations of bGH‑expressing pigs gained weight faster, were more feed efficient, and had less subcutaneous fat, but experienced high rates of gastric ulcers, arthritis, cardiomegaly, dermatitis, and renal disease.

Abstract

Genetic engineering of livestock is expected to have a major effect on the agricultural industry. However, accurate assessment of the consequences of transgene expression is impossible without multigenerational studies. A systematic study of the beneficial and adverse consequences of long-term elevations in the plasma levels of bovine growth hormone (bGH) was conducted on two lines of transgenic pigs. Two successive generations of pigs expressing the bGH gene showed significant improvements in both daily weight gain and feed efficiency and exhibited changes in carcass composition that included a marked reduction in subcutaneous fat. However, long-term elevation of bGH was generally detrimental to health: the pigs had a high incidence of gastric ulcers, arthritis, cardiomegaly, dermatitis, and renal disease. The ability to produce pigs exhibiting only the beneficial, growth-promoting effects of growth hormone by a transgenic approach may require better control of transgene expression, a different genetic background, or a modified husbandry regimen.