Eighteen Suffolk rams, purchased from three central test stations, were single- sire mated to both Suffolk and 1/2 Dorset, 1/4 Suffolk, 1/4 Rambouillet ewes at the University of Illin o is , Dixon Springs Agricultural Center, Simpson, Illin o is , U.S.A. Rams had been tested for growth over a 63-day period starting when they were approximately two months of age. Progeny lambs were weaned at 56+4 days of age and males were le ft intact. Lambs were fed a high energy ration ad libitum in confinement postweaning. Lamb body weights were taken at birth, 28+4 days of age, at weaning, and fortnightly postweaning until reaching 50 kg live weight. Progeny performance (birth, 60 and 120 day weights and gains between these ages) was regressed on sire's central test performance (average daily gain on test and weight per day of age at end of test). None of the partial regression co efficients were significantly different from zero. These data suggest that central test performance of Suffolk rams, measured on a 63 day test starting when rams are approximately two months of age, is not an accurate indicator of breeding value for growth.

D. F Waldron, D. L Thomas, J. M Stookey, Rohan L Fernando

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume IX. Breeding programs for dairy and beef cattle, water buffalo, sheep, and goats., , 639–644, 1986
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