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Variances Of Additive And Dominance Genetic Effects For Ovulation And Twinning Rates In A Population Selected For Twinning, L. Dale Van Vleck, K. E. Gregory
Variances Of Additive And Dominance Genetic Effects For Ovulation And Twinning Rates In A Population Selected For Twinning, L. Dale Van Vleck, K. E. Gregory
Department of Animal Science: Faculty Publications
Estimates of variances due to additive and dominance genetic effects and permanent and temporary environmental effects were obtained for ovulation and twinning rates from a composite population selected for twinning rate. Measures of ovulation rate after 11 mo of age on 2,317 heifers with a total of 19,209 measures were used. Twinning measures were on 1,522 first-parity cows, 1,311 later-parity cows with a total of 3,571 measures, and 1,704 all-parity cows with 5,100 measures. Models included fixed effects of year-season-age at calving for twinning, and year-season of birth, age in months, and calendar month of measurement for ovulation rate. Four …
Genetic Trend And Environmental Effects In A Population Of Cattle Selected For Twinning, L. Dale Van Vleck, K. E. Gregory
Genetic Trend And Environmental Effects In A Population Of Cattle Selected For Twinning, L. Dale Van Vleck, K. E. Gregory
Department of Animal Science: Faculty Publications
A selection experiment was established in 1981 to increase twinning rate in cattle. Results reported are through 1993 calf crops. Estimates of genetic parameters for a two-trait twinning and ovulation rate model with genetic groups were as follows: heritabilities of .03 for twinning and .07 for ovulation rates with a genetic correlation of nearly 1.00 and fractional permanent environmental variances of .06 for twinning and .05 for ovulation rate. Corresponding estimates when group effects were ignored were as follows: heritabilities of .08 and .08 and fractional permanent environmental variances of .02 and .04 for twinning and ovulation rates, respectively. Twinning …