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Heterogeneous Within-Herd Variance. 2. Genetic Relationships Between Milk Yield And Calving Interval In Grade Holstein Cows, T. H. Short, R. W. Blake, R. L. Quaas, L. Dale Van Vleck
Heterogeneous Within-Herd Variance. 2. Genetic Relationships Between Milk Yield And Calving Interval In Grade Holstein Cows, T. H. Short, R. W. Blake, R. L. Quaas, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Genetic and phenotypic (co)variances for mature equivalent yield of 4% FCM and calving interval were simultaneously estimated by REML for grade Holstein cows in first and second parity. Data were 305d mature equivalent lactation records and calving dates for 299,441 daughters of 2489 AI sires first calving from 1970 to 1985 in California, New York, or Texas. Data were divided into three time periods, and herds were partitioned into three within-herd-year phenotypic SD classifications for milk yield. Average FCM yield and calving interval increased with SD in all time periods for both parities. Genetic variance of calving interval showed no …
Heterogeneous Within-Herd Variance. 1. Genetic Parameters For First And Second Lactation Milk Yields Of Grade Holstein Cows, T. H. Short, R. W. Blake, R. L. Quaas, L. Dale Van Vleck
Heterogeneous Within-Herd Variance. 1. Genetic Parameters For First And Second Lactation Milk Yields Of Grade Holstein Cows, T. H. Short, R. W. Blake, R. L. Quaas, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Genetic and environmental (co)variance components for 4% FCM yield were simultaneously estimated by REML for grade cows from herds stratified by within-herd SD for 305d mature equivalent milk and time period. Data were lactation records from 299,441 daughters of 2489 AI b d s that calved for the first time from 1970 to 1985 in California, New York, or Texas.
Sire and residual variance components for FCM increased with SD in all time periods and were slightly larger for second than for first lactations. Residual components were of uniform size across time periods within each SD class, but sire components …