Studies were undertaken in the breeding facility of the Іnstitute of Animal Science NAAS "Gontarovka” on sheep 3-8 years of age of the Kharkiv type of breed of Merinos precoce. For this purpose, (early May 2020) the indexes of living mass were certain on electronic scales within 0.1 kg Whereupon animals were contained during May - September at the camp-pascual system with the additional fertilizing by grain of oat for 0.5 kg/ in a day and by a pasture on a natural pasture. Before the artificial insemination living mass of animals and their general increase was also certain for a period of preparation for the new cycle of reproduction, and after lambing their fecundity, the living mass of lambs, was taken into account at birth, in 20 - and 90-day's age. It is set that the living mass of sheep that in a next reproduction campaign bore lone persons increased for an unreproductive period by 19.8%, at giving birth twins this index grew by 22.2%, and for animals, giving triplet birth increased by 28.2%. Here living mass of sheep, that in a subsequent period had twins and triplets in an initial period of account felt strongly anymore about animals lambed individually on 6.1-7.3%. Thus, the difference between the first and second groups of uteruses appeared high-credible (р<0.001). At the end of the registration period difference on behalf of sheep 2 and 3 groups against the first group increased accordingly to 9.3% (р<0.001) and 13.5% (р<0.05). The average daily increases of lambs for the period from their birth to 20 days ha have a sufficiently clear connection with the indexes of increase of living mass of their mothers in the period of preparation for the new cycle of reproduction.
The average daily gain of yags for the period from their birth to 20 days is quite clearly related to the growth rates of live weight of their mothers in preparation for the new cycle of reproduction. The maximum average gain of lambs was obtained from ewes, the increase in live weight of which in the study period ranged from 10 to 15.9 kg. On this basis, lambs exceeded the results of peers from 6.1 to 17.9%. The indexes of living mass of eves before their insemination have positive coefficients of correlations with a living mass of lambs at wean from mother, and also average daily increases of lambs for the first 20 days of their life. They were made according to 0.346, 0.243 and 0.113.