Effect of Cow Parity and Calf Characteristics on Milk Production and Reproduction of Friesian Dairy Cows

摘要

Viability and profitability of livestock enterprise is evaluated by the percentage of pregnant females over a period of time after exposure to bulls and amount of milk yield per lactation. This attribute was tested using 20 seven-month in calf Friesian dairy cows. Effect of parity on; gestation period, calf birth weight, milk production, lactation length, and postpartum heat were tested in this study. Effect of calf sex and calf birth weight on milk production and postpartum heat of the dam was also studied. Parity highly influenced gestation period with Cows at parity 4 taking significantly the least number of days (269.5 days). The cows at parity 4 delivered calves that recorded the highest calf birth weight mean (39.0 kg). Milk production per day was significantly higher in the cows at parity 4 (17.0 L). There was significant positive correlation (r 2 =0.86, P0.001) between milk production and time to taken to exhibit postpartum heat Calf birth weight highly influenced milk production with dams of heavier calves producing significantly more milk than dams of lighter calves. Dams of heavier calves had significantly delayed postpartum heat. Calf sex significantly influenced milk production and postpartum heat. There was significant (r 2 =0.79, P0.001) positive correlation between calf birth weight and time to postpartum heat. Adoption and use of these findings will improve dairy industry through reducing calving intervals. Calf Birth weight should be used as important traits in performance testing of dairy cattle.