A comparison of Canadian Holstein bulls with those in the National Cooperative Dairy Cattle Breeding Project

Abstract

Direct comparisons of industry Holsteins to project Holsteins and to crossbred C lines in the National Cooperative Dairy Cattle Breeding Project were made at Ottawa. The industry Holstein group was composed of the eight Holstein young bulls in AI units awaiting proof in 1984, which had the highest pedigree indexes for protein yield. They were mated to both Holstein and crossbred C line females at Ottawa. Project Holstein and C line bulls were mated to females of their respective lines. Matings within the crossbred C line resulted in greater calving ease and fewer retained placentae (P < 0.05) than matings of Holsteins to either Holstein or C line females. Crossbred C line cattle were smaller and produced less milk, fat and protein in the first 24 wk of first lactation than Holsteins. Project and industry Holstein progeny were equivalent in early first lactation, milk fat and protein yield, but progeny of industry bulls were larger at all ages. Selection for protein yield over 14 yr in a 300 milking cow population produced young bulls of comparable genetic merit for production traits to that of intensely pedigree selected industry bulls. Key words: Holstein, selection, crossbred, yield, heifer