Selection for weaning weight and postweaning gain in Hereford cattle. III. Correlated responses to selection in milk yield, preweaning and postweaning traits.
Single trait selection was practiced in three lines of Hereford cattle. Bulls were selected within sire families for increased weaning weight (WW) in the WW line (WWL), for postweaning gain (PG) in the PG line (PGL) and at random in the control line (CTL). Correlated responses to selection indicated that predicted milk yield in cows and preweaning daily gain and yearling weight in bulls and heifers were genetically improved in both WWL and PGL. Larger correlated responses were observed in PGL than in WWL. Birth weight in bulls and heifers increased in PGL but no genetic change was observed in WWL. Feed efficiency, feed intake and fatness were evaluated in bulls on postweaning feedlot test. No significant correlated responses in feed efficiency were observed in either line. Larger correlated responses in feed intake were observed in PGL bulls than in WWL bulls, while fatness was significantly increased in both selection lines.
D000273:Adipose Tissue; D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000235:genetics* / Q000502:physiology; D004734:Energy Metabolism; D005260:Female; D007774:Lactation; D008297:Male; D008892:Milk / Q000378:metabolism*; D012044:Regression Analysis; D012641:Selection, Genetic; D013997:Time Factors; D014886:Weaning