The development of follicles in ewes can be observed by using B-ultrasound to more effectively promote the possibility of multiple births and high production. 12-13 days before estrus, 600-1100 international units of pregnant mare serum gonadotropin are injected intramuscularly into the ewes. Immediately after estrus, 500-750 international units of chorionic gonadotropin are injected intramuscularly on the same day. Dozens of eggs can be discharged. The number of follicles can be observed by using B-ultrasound to make judgments. (2) Use twin lamb or twin fetus. There are two types: aqueous and oily. Generally, 1 ml of aqueous products are injected subcutaneously into the neck of ewes 2 weeks and 5 weeks before mating, or 2 ml of oily products are injected into the buttocks muscle 2 weeks before mating. Using exogenous hormones and combining supplementary feeding to increase the number of ovulations and the proportion of twin lambs, the number of follicles during the observation period can be observed by using B-ultrasound. Experiments have shown that to achieve the ideal effect of using twin lambs, the following must be achieved: good feed conditions, meticulous feeding and management, the test sheep must have normal fertility, the fatness of the sheep measured by B-ultrasound is above medium, and the age is preferably 3-5 years old. (3) Supplementary feeding to stimulate estrus. One month before mating, in order to improve the nutritional level of the ewes, especially to supplement protein feed, it can not only promote estrus of the ewes, but also increase the number of ovulations. B-ultrasound can be used to observe the induction of ewes to give birth to twins.

Pay close attention to the delivery of ewes. The gestation period of ewes is about 150 days, and they enter the delivery room 7 days before delivery. The delivery room should be thoroughly cleaned and disinfected one week in advance, and straw should be laid. The temperature of the room should be maintained at about 8℃. All instruments used for delivery should be cleaned and disinfected, and the delivery staff should cut their nails short and disinfect them. Before delivery, the tail root, vulva and anus of the ewe should be cleaned, wiped and disinfected with 1% Lysol, and then wiped dry with a cloth. After the lamb is born, the umbilical cord head should be rubbed with iodine to prevent infection. If the sheep is observed by B-ultrasound, if the fetus is large or the fetal position is not correct, the fetal position should be corrected in time, artificial delivery should be performed to ensure the smooth delivery of the lamb. After delivery, the sheep is observed by B-ultrasound. If the lamb is in pseudo-death, it should be treated in time. First, clear the mucus and fetal fluid in the respiratory tract, wipe the nostrils, blow into the nostrils or perform artificial respiration.

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