Location: Location not imported yet.Title: Comparison of daughter performance of New Zealand and North American sires in US herds Author
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2012
Publication Date: 6/28/2012
Citation: Norman, H.D., Wright, J.R., Powell, R.L., Lawlor, T.J., Wolfe, C.W. 2012. Comparison of daughter performance of New Zealand and North American sires in US herds. Journal of Dairy Science. 95(Suppl. 2):684(abstr. 714). 2012. Interpretive Summary:
Technical Abstract: To improve fertility or other desired traits, some US graziers have chosen bulls from New Zealand (NZ), which relies extensively on seasonal calving and grazing. Performance for parities 1 through 5 of daughters that calved in the same US herd in the same year-season was compared for NZ and North American (NA; Canadian and US) AI Holstein and Jersey bulls; NZ Holsteins also included Friesians. Cows that calved between January 2000 and July 2010 in all US herds were included as well as in a subset of seasonally calving herds ('60% of calvings in February through April). First-lactation Holstein data included records from 438 herds with 1,443 daughters of 54 NZ bulls and 26,444 daughters of 3,055 NA bulls; Jersey first-lactation data included records from 538 herds with 2,714 daughters of 65 NZ bulls and 76,281 daughters of 1,631 NA bulls. The seasonal calving subset included 20% of matings to NZ Holstein bulls and 11% of matings to NZ Jersey bulls. Mean milk and protein yields across all parities were higher for NA daughters than for NZ daughters (497 kg milk and 6 kg protein for Holsteins; 264 kg milk and 3 kg protein for Jerseys); mean fat yield was nearly equal for Holsteins but lower (2 kg) for NA Jersey daughters. Mean somatic cell scores were higher for NZ than NA daughters (0.15 for Holsteins; 0.08 for Jerseys). Mean days open were fewer for Holstein NZ daughters (9.9 d) but were greater for Jerseys (1.3 d). Little difference was found between NZ and NA Holstein daughters for calving ease and stillbirth rate. For 17 Holstein type appraisal traits, NA daughters scored higher for stature, fore udder attachment, rear udder height, and udder depth. For 13 Jersey type appraisal traits of 1,267 NZ daughters and 33,371 of their contemporaries, NA daughters scored higher for stature, dairy form, fore udder attachment, rear udder height and width, and udder depth but lower for strength and thurl width. Results for seasonally calving herds were similar. Overall merit of various selection alternatives should be judged on performance of all traits with economic value considered.