Genetic evaluations for the length of productive life based on actual DHIA culling data have been available in the US since January 1994. Although substantial genetic variation in productive life exists, the reliability of selection is often low, particularly for recently progeny-tested bulls having daughters that have not yet had an opportunity to be culled. Correlated production and conformat...

The study was carried out in a Polish Black-and-White cattle population, represented by 167 AI sires, 200 young tested bulls, 190 bull-dams, and 606 randomly chosen cows from commercial herds. The fragment of the bovine prion protein gene (PRNP) coding the octapeptide-repeat sequence, was identified by PCR analysis. Two different gene variants of 349 bp and 373 bp in size, produced three genoty...

Genetic evaluations of Holstein bulls from the US were matched with Canadian, Italian, Mexican, and Netherlands evaluations for the same bulls. Conversion equations for milk yield were computed by least squares, Goddard, and Wilmink methods. Accuracy was assessed by splitting data and applying equations developed from one subset to the other subset. Methods were judged by mean differences betwe...

Genetic evaluations for the length of productive life based on actual DHIA culling data have been available in the US since January 1994. Although substantial genetic variation in productive life exists, the reliability of selection is often low, particularly for recently progeny-tested bulls having daughters that have not yet had an opportunity to be culled. Correlated production and conformat...

The usefulness of multinational data for the improvement of national estimates of genetic merit of Holstein bulls was assessed. For 222 bulls, combined US-Canadian evaluations and evaluations from the US only from January 1993 for milk, fat, and protein yields were compared with their US only evaluations from August 1997. The correlations between the 1993 and 1997 evaluations and the standard d...

Seven yearling Holstein bulls were given 0, 20, 40, 60, 80, 100 and 200 micrograms NIH-LH-B9 during a 7-day complete Latin square design experiment. Treatments were administered via jugular cannulas at 0900 hr, and blood was collected at 60, 30 and 0 min before treatment, at 15-min intervals for 3 hr after treatment and at 30-min intervals from 3 to 7 hr after treatment. Luteinizing hormone (LH...

Two ejaculates were harvested by electroejaculation on each of 3 d per week for 14 wk from 14, 12- to 24-mo-old Holstein bulls. Ejaculates during the first 2 wk served to stabilize sperm output. Data for the remaining ejaculates were used in a components of variance approach to determine the number of bulls per treatment and ejaculates per bull that would be needed to provide adequate sensitivi...

Bovine chromosome six (BTA6) harbors up to six quantitative trait loci (QTL) influencing the milk production of dairy cattle. In stark contrast to human, there is long-range linkage disequilibrium in dairy cattle, which has previously made it difficult to identify the mutations underlying these QTL. Using 38 microsatellite markers in a pedigree of 3,147 Holstein bulls, we fine mapped regions of...