Effects of Early and Late Breeding of Dairy Cows on Reproduction and Production in Current and Subsequent Lactation

Effects of early and late breeding post partum on reproduction and production were investigated in a Holstein herd. Cows were assigned randomly to two groups at calving: an early group bred at the first observed heat following 50 days postpartum and a late group bred at first observed heat 80 days postpartum. Early versus late breeding resulted in intervals to first service of 72 + 18 or 93 +-17 days; conception at 88 + 33 or 121 + 40 days postpartum; and 1.50 (range 1 to 3) or 1.96 (range 1 to 5) services per conception.