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J. Dairy Sci. 87:2307-2313
© American Dairy Science Association, 2004.

Variances of and Correlations Among Progeny Tests for Reproductive Traits of Cows Sired by AI Bulls

J. S. Clay, B. T. McDaniel and C. H. Brown

Department of Animal Science, North Carolina State University, Raleigh 27695-7623

Corresponding author: J. S. Clay; e-mail: john_clay{at}ncsu.edu.

Estimates of daughter fertility were computed using first artificial insemination (AI) breedings reported to the US Dairy Herd Improvement Association (DHIA) from 1995 through 1997. An animal model was used to compute estimated breeding values (EBV) of daughter groups with fixed effects of herd-year-month bred and classes of early lactation energy-corrected milk, days in milk (DIM) when bred, and parity. Standard deviations and ranges of bull EBV for daughter fertility for DIM were 9.1 and –31 to 18; standard deviations and ranges of bull EBV for daughter fertility for nonreturn were 3.8 and –11 to 10. Correlations were computed for EBV for daughter fertility with EBV for mating bull fertility and with predicted transmitting abilities (PTA) for milk, somatic cell score (SCS), and productive life for bulls (213) with minimums of 200 matings and 100 progeny with reproductive traits. None of the correlations among EBV for reproductive traits differed from 0.0. Correlations of EBV for daughter fertility with PTA for productive life were significantly positive. PTA for yield traits were not correlated with EBV for daughter differences in nonreturn or DIM. Very low correlations of EBV for daughter reproductive traits with PTA for yield indicate that, in order to improve daughter fertility, fertility must be incorporated in sire selection decisions.

Key Words: daughter • reproduction • fertility • nonreturn

Abbreviation key: CI = calving interval, DIM1 = days in milk at first AI mating, DIM1-S = EBV of sire for days in milk at first AI mating, ECM = summit daily early-lactation energy-corrected-milk, ERCR-S = estimated relative conception rate of sire or EBV for rate of nonreturn in 70 d for first AI mating, ERCR-MB = estimated relative conception rate of mating bull or the difference from average AI mating bull of herdmates for rate of nonreturn in 70 d for first AI mating, NR70 = nonreturn in 70 d to first AI mating






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