Through artificial means, the physiological reproductive environment of ewes is improved to encourage ewes to produce twins or more lambs per litter. Methods for inducing twins and multiple births: supplementary feeding to induce estrus. One month before mating, improve the composition of the diet, improve the nutritional level of the ewes, and especially supplement protein feed. Supplementary feeding can not only increase the estrus rate of ewes, but also increase the number of ovulations, induce ewes to produce twins or even multiple births. In this process, the effect can be observed through sheep B-ultrasound.

Hormone pathway. This pathway is consistent with superovulation treatment. Its treatment method is also to test the estrus of the ewes first, or observe their estrus through sheep B-ultrasound. On the 12th or 13th day of the estrus cycle, 600-1100IU of pregnant mare serum gonadotropin is subcutaneously injected. Some people advocate injection on the second day of the cycle, which can reduce the variation of ovulation response and avoid the adverse phenomenon of high ovulation rate, which is conducive to improving the breeding rate of lambs. Due to the great differences in the response of breeds and individuals to hormones, it is difficult to find a uniform dose suitable for each sheep. Therefore, the appropriate dosage should be determined after preliminary tests on local specific breeds, or the effect of each dosage should be observed using sheep B-ultrasound. Use twin lamb hormone or twin fetal hormone. The principle is to couple artificially synthesized exogenous steroid hormones with carrier proteins to stimulate the production of reproductive hormone antibodies in animals. The antibodies combine with the corresponding endogenous steroids in the peripheral blood to inactivate some or all of the steroid hormones, thereby weakening or eliminating the negative feedback effect of the hypothalamus-pituitary gland, causing the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) pulse frequency to increase, resulting in more follicles on the ovaries to develop and mature, thereby increasing the ovulation rate of sheep, which can also be clearly seen on sheep B-ultrasound. An important feature of this hormone is that it increases the twin lamb rate, not 3 lambs or 4 lambs. It is simpler, more cost-effective, and can improve the survival rate of lambs than using pregnant mare serum or twin lamb breeding to increase the reproduction rate.

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