Effects of calving ease-calf survival on production and reproduction in Holsteins.

Data on 23,873 Holstein cows on official test of the Quebec Dairy Herd Analysis Service were analyzed for effects of calving ease-calf survival on cow productivity; data on 35,773 Holstein cows were analyzed for effects on culling and reproductive efficiency. Traits were milk, fat, and protein yields, percent fat and protein for 90-day and 305-day lactations, days from calving to first service and conception, percentage conception rate from first service, and services per conception. The effect of calving ease-calf survival on production traits was not significant in most cases except surgical calvings associated with stillbirth. For these the loss of 305-day production was approximately 300 to 500 kg milk, 8 to 17 kg fat, and 8 to 14 kg protein. Stillbirth in nonsurgical calvings was associated with lower production than when the calf survived; differences were 100 to 400 kg milk, 4 to 11.5 kg fat, and 2.5 to 13 kg protein. Age of cow and calving ease-calf survival significantly affected all measures of reproductive efficiency. Reproductive efficiency declined with advancing age. Effect of calving ease-calf survival tended to be more pronounced when calving was associated with stillbirth.