Heritabilities and genetic and phenotypic correlations among 14 linear type traits were estimated from Holstein Association data by multiple trait REh4L. Data used for parameter estimation were records of 779,391 daughters of 871 sires included in the January 1988 sue evaluation. Each daughter was represented by her appraisal closest to 30 mo of age. Highest heritability was -37 for stature, and lowest was .10 for foot angle. Gains in reliability from using correlated traits in multiple trait prediction were large for some traits (up to 60% for foot angle for cows). Final score variance parameters were estimated from 953,596 records, which were 43% of records included in the national sire evaluation. Sire models that adjusted or did not adjust for merit of mates were compared. Heritability of fi-

No abstract

No abstract

Methods were explored for removing within-cow differences between a.m. and p.m. milk yields to allow direct comparison of consecutive milk yields. Daily a.m. to p.m. ratios of milk yield were studied for 504 lactations of 310 Holstein cows. Ratios varied within lactations and among cows. When the incomplete gamma function was used to characterize lactation curves, 89% of the variation in individual milk yields was explained when an a.m.-p.m. term was included. The a.m. to p.m. ratios increased over the course of lactations. Within-cow adjustment factors for a.m.-p.m. milking, based on weighted and unweighted averages of previous a.m. to p.m. ratios, changed as lactation length increased. A weighted moving average technique, which weighted the last a.m. to p.m. ratio by .15, compared with .85 for previous ratios, was considered to be the optimal method of calculating a factor for removing a.m.-p.m. effects.

No abstract

No abstract

No abstract

No abstract