use the fallopian tube fimbria to contract. If it is not relaxed in time, the follicle will rupture and the egg discharged later may fall into the abdominal cavity, which will reduce the conception rate; ② Touching the follicle will increase the workload and is meaningless, because the duration of estrus in dairy cows is very short, most of which will not exceed 12 hours. The interval from the first standing estrus to ovulation is generally 24-32 hours, the survival time of the input sperm is 24-30 hours, and the life span of the egg is 10 hours. Frequent standing estrus can be mated 8-12 hours after breeding to obtain a satisfactory estrus conception rate; ③ During the estrus of dairy cows, more than 2 waves of developing follicles will be generated, and the development of single or several follicles will occur one after another. Simply relying on rectal touch to check the development of follicles to decide when to breed may often cause confusion or inaccuracy. The application of cattle B-ultrasound diagnosis can solve this problem.

Rectal palpation to check the development of follicles still has certain clinical application value in some cases. ① When using sex-controlled frozen sperm, the position of mature follicles can be touched immediately after frequent standing estrus. During insemination, semen is directly injected into the same side of the mature follicle, but the follicle must not be touched. This can increase the estrus conception rate to a certain extent; ② For those who have repeatedly infertile, those with estrus disorders and those who are not in estrus, the ovaries should be checked as a matter of course to determine the real cause.

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