EVALUATION OF NON GENETIC FACTORS AFFECTING MILK PRODUCTION TRAITS OF HOLSTEIN CATTLE

Authors

1 Department of Husbandry and Animal Wealth Development, Faculty of Veterinary Medicine, Mansoura University, Egypt

2 Department of Animal Wealth Development, Faculty of Veterinary Medicine, Zagazig University, Egypt

Abstract

This study was carried out to evaluate the effects of a ge at calving (AC), parity, days in milk (DIM), calving interval (CI), d ays open (DO), d ry period (DP), number of services per conception (NSC), s eason of calving on peak milk yield (PMY), time to attain peak milk yield (TPMY), 305 day mature equivalent (305- DMY) and total milk yield (TMY). Age at calving had significant effect (P≤ 0.05) on all traits studied except TPMY. DIM had a highly significant effect (P< 0.001) on PMY (37.14- 39.18 kg), TPMY (99.29- 194.08days), 305-DMY (8692.86 - 9760.65 kg) and TMY (4552.82- 12416.95 kg) respectively. Furthermore, DO and DP had a highly significant effect on PMY (33.72- 40.29 and 31.81 41.08 kg, respectively), TPMY (152.01- 165.14 and 139-165 day s , respectively), 305-DMY (8613.83- 9606.83 and 7266.76- 9699.76 kg, respectively) and TMY (8057.51- 8865.18 and 6682.97- 8850.30 kg, respectively). NSC had a highly significant effect (P< 0.001) on all traits studied except PMY. On the other hand, parity had no significant influence (P ≥ 0.05) on all traits studied except PMY. CI had no significant effect on all traits studied except 305-DMY. Moreover, season of calving had no significant effect on all traits studied. In conclusion, these factors should be accounted for genetic evaluation process. At farm level, management decisions such as selec&#116;ion and culling, and feeding should made putting these factors into consideration in order to achieve more reliable evaluation.

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