A COMPARISON OF CANADIAN HOLSTEIN BULLS WITH THOSE IN THE NATIONAL-COOPERATIVE-DAIRY-CATTLE-BREEDING-PROJECT

Direct comparisons of industry Holsteins to project Holsteins and to c rossbred C lines in the National Cooperative Dairy Cattle Breeding Pro ject were made at Ottawa. The industry Holstein group was composed of the eight Holstein young bulls in Al units awaiting proof in 1984, whi ch had the highest pedigree indexes for protein yield. They were mated to both Holstein and crossbred C line females at Ottawa. Project Hols tein 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 e ither 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 l actation than Holsteins, Project and industry Holstein progeny were eq uivalent in early first lactation, milk fat and protein yield, but pro geny 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.