This study was conducted to determine the repeatability estimates of milk yield by parity and age in 390 Friesian – Bunaji crossbred (25% Friesian and 75% Bunaji) cows that had 7 lactation records. Data collected on each animal include age, parity and weekly milk yield for 20 weeks. The results revealed that milk yield per week were between 9.41±00.79 – 14.07±1.03 litres. The cows within the ages of 1-10 years had consistently similar yield throughout the 140 day lactation period. Significant effect (p<0.05) had been observed on milk yield by parities. The yield in parities 4 and 8 were significantly highest. The yield increases irregularly with age of the cows and the highest values were observed in cows of 7 and 10 years while the lowest were in ages 1 to 8. Repeatability estimates was low (0.208) in parity 5, medium (0.416 and 0.357) in parities 4 and 7, high (0.704, 0.790 and 0.722)in parities 1, 3 and 6. In this study, high repeatability estimates of milk yield in Friesian -Bunaji suggests that culling low producing heifers or cows will improve average milk yield in the herd. The low repeatability estimates for parity 5 (0.208)indicates that the parity was highly influenced by environmental factors and evaluation should be made when more records are available. 1480516069.php
REPEATABILITY ESTIMATES OF MILK YIELD BY PARITY AND AGE IN FRIESIAN- BUNAJI CROSSBRED COWS
Date : 2017-12-06 Volume : 9