Comparison of breeding values among cows with exceptional longevity and their contemporary herdmates in German Holsteins
Abstract. The present analysis compares the estimated breeding values (EBVs), relative breeding values (RBVs), and daughter yield deviations (YDs) of cows with exceptional longevity with their contemporary herdmates. In addition, the relative breeding values of their sires were compared among these two daughter groups; the RBVs of the sires were also compared with the proportion of their daughters with exceptional longevity. Data included 5037 sires born between 1963 and 1996 with a total of 61 988 daughter; of these sires, 486 had sired daughters that completed more than nine lactations (exceptional cows) and 4957 sires had sired the contemporary herdmates. Exceptional cows had on average significantly lower EBVs for milk yield, fat and protein yield, and significantly lower YDs for milk and protein yield in the first three lactations, significantly lower RBVs for milk production and type but significantly higher RBVs for somatic cell score and functional longevity. The sires of exceptional cows had significantly higher RBVs for somatic cell count (RZS), functional longevity (RZN), and fitness (RZFit) in comparison to the sires of contemporary herdmates. Correlations among the proportion of exceptional cows per sire and RZN, RZS as well as RZFit were positive, whereas milk production (RZM) showed a negative correlation. An increase in the number of cows with exceptional longevity may be possible through a relative total breeding value with high positive weights for RZN, RZS, and RZFit but negative weights for RZM and type (RZE).