Bivariate Animal Model Estimates of Genetic, Phenotypic, and Environmental Correlations for Production, Reproduction, and Somatic Cells in Jerseys

摘要

Correlations were obtained between 18 response vari- ables of a Jersey herd (Florida Agricultural Experiment Station, Gainesville) for 374 first lactations. Estimates were from the use of multivariate, derivative-free, re- stricted maximum likelihood procedures with the sim- plex method of partial maximization. Estimates agreed closely with those obtained previously by other methods in this and other dairy populations. All correlations between yields were high and positive; those between yields and days from parturition to first service were negative and near zero. Correlations between yields and somatic cell scores were moderate and negative; those between yields and constituent percentages in general were negative, except for the yield and percent- age of the same constituent. Genetic correlations be- tween chloride content and somatic cells and between measures of somatic cells were 1.0. Results suggest that single-trait selection for milk yield should result in correlated increases in constituent yields with slight decreases in percentage composition of constituents and somatic cell counts.Jersey;bivariate animal model;corre- lations