Variances, Repeatabilities, and Age Adjustments of Yield and Fertility in Dairy Cattle
Open Access
- 1 February 1983
- journal article
- research article
- Published by American Dairy Science Association in Journal of Dairy Science
- Vol. 66 (2), 281-292
- https://doi.org/10.3168/jds.s0022-0302(83)81788-3
Abstract
Breeding receipts from artificial insemination were matched with records of milk yield from northeastern USA. Nine measures of yield and 10 measures of fertility were investigated. A completely random model with herd-year-season, sire and interaction of sire by herd-year-season was applied by parity; interaction of sire by herd-year-season was not important except possibly for fertility of virgin heifers. Sires accounted for 6-7% of yield variation and herd-year-seasons accounted for about 45%. Measures of fertility had small sire variances, and herd-year-season variance was much smaller than for yield. Effects of age within parity were significant for yield from ordinary least-squares analysis. Age adjustment factors were obtained for measures of yield. Repeatabilities of 1st- and 2nd-parity yield ranged from 0.40-0.61; repeatabilities of fertility were 0.03-0.13. Repeatabilities of virgin heifer and 1st-parity fertility were 0.01-0.03, suggesting heifer and cow fertility may not be related.This publication has 16 references indexed in Scilit:
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