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Journal of Dairy Science Vol. 46 No. 1 27-33
© 1963 by American Dairy Science Association ®
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Relationship Between Longevity and Production in Holstein-Friesian Cattle

R. F. Gaalaas and R. D. Plowman

Dairy Cattle Research Branch, Animal Husbandry Research Division, USDA, Beltsville, Maryland

ABSTRACT

Production and age data on 3,879 daughters of 123 Holstein sires were used to study the relationship between first-lactation milk and milk fat production and longevity in 79 herds. They were divided into six groups by type of ownership.

The average age at the start of the first lactation was 32.4 months, and at the start of the last complete lactation (final age) was 61.1 months. Linear regressions of final age on first-lactation production were 0.071 months/lb milk fat and 0.024 months/10 lb of milk. Corresponding correlation coefficients were 0.188** and 0.179**, respectively. Differences between the group regression coefficients were not statistically significant. Individual sire regressions of final age on milk production varied from –0.089 to +0.129/10 lb of milk and from –0.253 to +0.346/lb milk fat. The differences between the sire regression coefficients were significant (P < .05). Regression coefficients at different levels of milk production within-group varied widely, but differences between these regressions were statistically significant in only one group (P < .05).

The regression and correlation coefficients were small but highly significant. There seems to be little doubt that on the average in these data, the higher-producing first-lactation cows had a somewhat longer productive life in these herds.






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Copyright © 1963 by the American Dairy Science Association ®.