断奶月龄对秦川母牛繁殖性能及犊牛生长性能的影响OA

To investigate the effects of different weaning ages on the reproductive performance of Qinchuan cows and the growth performance of calves,a total of 208 prepartum Qinchuan cows with similar parity and expected delivery dates were selected for this study,and the dietary and feeding management conditions were consistent throughout the experimental period.Four treatment groups were set up where calves were weaned at 3 months,4 months,5 months,and 6 months of age,respectively.The body weight,body size in-dicators of calves at different stages,and reproductive performance-related indicators of cows were mea-sured to analyze the impact of weaning age on the aforementioned indicators.The results showed that:①The birth weight of male calves was(28.98±4.08)kg,which was significantly higher than that of female calves(27.06±3.41)kg(P ≤0.05).The withers height(71.32±3.37)cm,chest circumference(72.94±3.88)cm,and chest width(14.63±1.10)cm of male calves were also significantly higher than those of fe-male calves(withers height(70.04±2.53)cm,chest circumference(71.86±3.58)cm,chest width(14.19±1.00)cm)(P≤0.05).However,there were no significant differences in hip height,body length,abdominal circumference,or pin bone width between newborn male and female calves(P＞0.05).②Weaning age had a significant effect on the weaning weight and various body size indicators of both male and female calves(P≤0.05).Nevertheless,as the age increased,the influence of weaning age on calf growth performance gradually diminished.At 6 months of age for female calves and 12 months of age for male calves,there were no longer significant differences in body weight and all body size indicators among calves from different weaning age groups(P＞0.05).③Different weaning ages of calves had significant effects on all indicators of cow reproductive performance.Specifically,the average postparturient first estrus time of cows in the 3-month weaning group was(45.2±6.8)days,which was significantly shorter than that in the 6-month wea-ning group(62.5±7.3)days(P ≤0.05).The average number of inseminations in the 3-month weaning group was(1.8±0.5)times,significantly fewer than that in the 6-month weaning group(2.5±0.6)times(P≤0.05).The calving interval of cows in the 4-month weaning group((390.2±4.8)days)was signifi-cantly shorter than that in the 5-month weaning group((401.6±6.3)days),and the conception rate and calving rate were 86.3％and 79.4％,respectively,which were significantly higher than those in the 6-month weaning group(80.2％and 74.6％).Based on the comprehensive analysis above,it is recommended that the weaning age of Qinchuan female calves can be advanced to around 4 months old,and that of male calves to around 3 months old,so as to further improve the reproductive capacity of cows.