Heritabilities and genetic and phenotypic correlations among yields of milk, fat, protein, and percentages of fat and protein were estimated from 40,984 first lactation records of daughters of 488 young and 75 proven Holstein sires using multivariate REML and a sire model accounting for relationships and sire groups. Proven sires were treated as fixed effects. Heritabilities for yields of milk, fat, protein, and percentages of fat and protein were .29, .31, .25, .65, and .61, respectively. Genetic correlations of milk with yields of fat, protein, and percentages of fat and protein and correlations of fat yield with fat percentage were .45, .79, -.49, -.54 and .56, respectively. Genetic correlations among yields and among percentage of fat and protein were the same (.62). Genetic and phenotypic correlations of protein percentage with fat and protein yields and correlations of fat percentages with protein yield were small (-.13 to .11). Phenotypic correlations were .73 to .90 among yields of milk, fat, and protein; -.31 for milk and fat percentage; -.39 for milk and protein percentage; and .38 for fat yield and fat percentage. Estimates were consistent with an earlier study utilizing data from the same population and also with other reports.

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Heritabilities, genetic and phenotypic correlations among lifetime yields of milk, fat and protein, herdlife, productive life and number of lactations initiated in the herd were estimated from records of 44,933 progeny of 427 young and 119 proven Holstein sires in 1949 herds using a multivariate Reml technique to fit a sire model with relationships among young sires. Proven sires were fitted as fixed effects. Heritabilities of lifetime traits ranged from 0.005 to 0.030, suggesting little scope for direct selection for lifetime performance traits. Productive life had highest genetic correlation with lifetime fat yield (0.934), but correlations with lifetime milk and protein yields were smaller and similar (0.773 and 0.772). The number of lactations also had highest genetic correlation with lifetime fat yield. ZUSAMMENFASSUNG: Genetische Parameter von Lebensleistungsmerkmalen bei Holsteinkühen Heritabilitätswerte, genetische und phänotypische Korrelationen zwischen Lebensleistungsmerkmalen für Milch, Fett und Protein, Lebensdauer, produktive Zeit und Zahl Laktationen wurden won 44933 Nachkommen von 427 jungen und 119 nachkommenschaftsgeprüften Holsteinstieren in 1949 Herden mittels einer multivariablen REML-Technik geschätzt, die auf einem Vatertiermodell mit Verwandtschaft zwischen den jungen Stieren beruhte. Geprüfte Stiere wurden als fixe Effekte im Modell berücksichtigt. Heritabilitätswerte dieser Merkmale rangieren von 0.005 bis 0.03, so daß wenig Aussichten für Erfolg direkter Selektion auf Lebensleistungsmerkmale besteht. Die Länge des produktiven Lebens hatte die höchste genetische Korrelation mit Lebensfettmenge (0.934), aber die Korrelationen mit Milch- und Protein-Lebensleistung waren kleiner und ähnlich (0.773 und 0.772). Die Zahl der Laktationen hatte die höchste genetische Korrelation mit der Lebensfettmenge.

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