B-ultrasound examination of dairy cows: the effects of lactation and milking on uterine recovery in dairy cows

Lactation stimulates the secretion of oxytocin more strongly than milking, and oxytocin can promote smooth muscle contraction and reduce the size of the uterus. Increasing the number of milking promotes the secretion of oxytocin, which is beneficial to uterine recovery. However, some people believe that whether it is lactation or milking, increasing the number of times is not conducive to uterine recovery, probably because the formation of LH pulses is inhibited. In addition, the increase in lactation reduces ovarian activity and disrupts the postpartum reproductive cycle. The higher the lactation, the later the first ovulation after delivery, and the higher the dark estrus rate. The first ovulation of milking cows after delivery is closely related to uterine recovery, and this condition can be judged using B-ultrasound of dairy cows. The physical stimulation of calves to cows provides the original power for the uterine recovery process of postpartum dairy cows, and the progesterone secreted by the corpus luteum will inhibit uterine immunity.

Effects of parity and age on uterine recovery in dairy cows by B-ultrasound examination

Clinically, it has been found that the recovery of dairy cows' uterus does tend to be delayed with age, and the speed of uterine recovery is delayed with the increase of parity, and the uterine recovery speed of first-parity cows is the fastest. Therefore, when using B-ultrasound to check the recovery of the uterus in dairy cows after parity, it can be clearly found that the uterus of primiparous dairy cows recovers very quickly. However, some people believe that the level of reproductive hormones in dairy cows has nothing to do with parity. Whether this can reveal that the reason for the effect of parity on uterine recovery is caused by the decline of nutritional metabolism and poor degradation of uterine myosin, rather than being directly related to parity, of course, this inference needs further research.

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