The use of hormones in dairy farming, clinical application technology, estrus induction technology. Generally, if the cow is still not in estrus or pregnant after 85-95 days, the cow is checked by B-ultrasound. The body condition is good and healthy. First, exclude metritis. The cow with a daily yield of less than 25kg and no continuous injection of any reproductive hormones in the recent period can consider hormone induction of estrus. During the induction process, it is necessary to frequently use Cow B-ultrasound to detect the condition of follicles.

Cow B-ultrasound combined with rectal examination of the ovarian corpus luteum is well developed (1.5-2cm in diameter) or corpus luteum cyst (ovary is spherical with a diameter of 3-4cm and elastic texture). Vitamin ADE20mL and PG (sodium cloprostenol) 0.3mg can be injected intramuscularly respectively. Observe for 3-9d, breed at the right time for estrus, and observe with cow B-ultrasound. In the reaction, PG 0.3mg is injected intramuscularly on the 9th day. At this point, PG induction of estrus ends. If it is ineffective, it should not be used again in the near future, and the synchronous estrus method can be used instead.

B-ultrasound combined with rectal examination of cattle shows that the ovaries have neither corpus luteum nor early follicles, and are in a dormant state. It is recommended to use PMSG 1000IU, and inject it intramuscularly once every 3 days. Because it is a placental hormone, it has less negative impact on the pituitary gland, and its performance focuses on FSH, so the effect is ideal.

Balance technology for endocrine disorders in dairy cows: FSH and LH are injected intramuscularly at a ratio of 5:1 or 4:1. For example, FSH 200IU is injected intramuscularly on the first day, and LH50IU is injected intramuscularly on the second day, just once. It is not recommended to use ovulation-stimulating agent No. 3, because it is a synthetic product similar to GnRH. Long-term, repeated, and high-dose application is prone to desensitization of the pituitary-ovarian axis, and has anti-fertility effects of inhibiting ovulation and blocking the estrus cycle, which can be well observed on B-ultrasound for cattle.

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