Relationships among first lactation, longevity, and lifetime performance traits of holsteins [electronic resource].

Includes references.

Data on 9286 German Friesian cows, daughters of 666 sires and with first calvings from 1979 to 1994 in 23 herds from one region in Northern Germany, were analysed for relationships of first lactation traits with lifetime performance using multitrait REML mixed model. Effects of herd-year- season,and age at first calving were considered to be fixed, and effects of sires and residuals were considered to be random. Individual lactation records were precorrected for the fixed effect of year and month of calving before lifetime totals were calculated. Each cow was given at least a 3 years opportunity for production. All genetic and phenotypic correlations were positive except correlation of first lactation percentage traits. Genetically. first lactation milk yield was highly correlated with most measures oflifetime performance, 0.54 to 0.96; correlations with measures oflongevity were relatively smaller. 0.41 to 0. 78.

Summary in Arabic.

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