Correlations of Neutrophil Phagocytosis for Proven Bulls with Traits of Economic Importance of Their Daughters

Neutrophil phagocytic parameters, measured on 25 AI Canadian Holstein bulls, were investigated for evidence of association with production and type traits, SCC, and survival of dairy cows. An animal model and REML methodologies were used to evaluate the bulls for their neutrophil potential phagocytic activity and capacity. A total of 42,103 first lactation records, collected from 1985 through 1993 for 2919 Quebec dairy herds, were used to obtain EBV for SCC and log SCC for 697 sires. From the same population of cows, 32,900 lactation records were used to calculate EBV for survival after first lactation for 338 sires. Correlations of EBV for SCC and log SCC with all other traits were not significant. Official Canadian ETA for type traits related to the mammary system tended to be positively correlated with phagocytosis parameters. Official Canadian ETA for production traits tended to be negatively correlated. The ETA for milk protein had a significant negative correlation with potential phagocytic activity. Survival after first lactation was significantly associated with ETA for dairy character, milk fat, and fat percentage.