Factors Influencing Dairy Cattle Longevity

Abstract

Analysis of disposal records on 505 Holstein-Friesian and 489 Jersey cattle in the USDA herds at Beltsville, Maryland, showed that 41.3% of the Holsteins and 21.3% of the Jerseys were removed from the herd as nonbreeders. Udder troubles constituted the 2d largest group of reasons for disposal, the percentages being 10.5 and 9.6 for the 2 breeds, respectively. No cattle were culled for low production or poor type in these herds during the 40-yr. period covered by the data. Longevity of individual cows was measured in terms of age at last calving prior to disposal. The automatic selection differential for this trait averaged approximately 1.5 yr. per generation for both breeds. Heritability estimates based on intra-sire daughter-dam regressions and paternal half-sib correlations did not differ significantly from zero. Correlations between longevity and first-lactation milk yield were .18 in the Holstein and .19 in the Jersey data. Similar values were obtained regarding butterfat yield. The results indicate that differences in longevity between individual cows are determined largely by nongenetic influences. Efforts to improve this trait genetically through direct selection or by improving dairy type probably would be ineffective. Also, the study indicates that no deleterious effects on longevity need be expected by concentrating selection of progeny-tested sires on the basis of first-lactation production records of their daughters.