IMPROVED WOOL PRODUCTION IN TRANSGENIC SHEEP EXPRESSING INSULIN-LIKE GROWTH-FACTOR-1

Transgenic sheep were produced by pronuclear microinjection with a mou se ultra-high-sulfur keratin promoter linked to an ovine insulin-like growth factor 1 (IGF1) cDNA. Five transgenic lambs resulted from the m icroinjection of 591 embryos; one male and one female showed IGF1 expr ession in the skin. A progeny test of the ram was carried out by matin gs to 43 non-transgenic ewes, Of 85 lambs born, 43 (50.6%) were transg enic. At yearling shearing (approximately 14 months of age), clean fle ece weight was on average 6.2% greater in transgenic animals than in t heir non-transgenic half-sibs, with a greater effect in males (9.2%) t han females (3.4%), Transgenics showed a small but significant increas e in bulk, but male transgenics had a lower staple strength than femal e transgenics and non-transgenics which did not differ significantly. There were no significant differences in fiber diameter, medullation, and hogget body weight. To our knowledge this is the first reported im provement in a production trait by genetic engineering of a farm anima l without adverse effects on health or reproduction.