REPRODUCTIVE CROSSING OF MERINO CROSSES WITH ROMANOV BREED TO CREATE A NEW GENOTYPE OF MULTIPAROUS SHEEP

Abstract

The paper presents the results of the study of multiparous ewes, viability and growth of the offspring, mutton production, profitability of the sheep breeding products obtained from crosses of the Caucasian Merino breed with the Romanov breed during their reproductive crossing in comparison with purebred sheep of the original breeds in order to create a new genotype of multiparous sheep with white uniform wool. The studies were carried out in the Krasnodar Territory; 6-7 groups of experimental young animals reared to 8 months of age were obtained from various variants of the parental pairs selection. It has been found that the sheep of the Romanov breed differed by greatest multiparous characteristics: 2,21±0,14 lambs per 1 ewe, 1,95-1,89 times (P <0,001) more than the merinos. Half-blooded Romanov x Caucasian ewes provide increased multiparous characteristics: with reproductive crossbreeding it is 1,91±0,08 lambs, or 1,63 times more than the merinos, and with a back crossing it is 1,74±0,15 lambs or 1,49 times higher than the level of purebred animals of the Caucasian breed (1,17±0,05 lambs). Caucasian x Romanov half-blooded ewes (reciprocal variant), with reproductive crossing, also had a greater multi-fetus pregnaney (1,84±0,09 lambs), 1,57 times higher than the merinos. The best survival rate of lambs (98,3%), as compared with the offspring of their multiparous herd mates (91,8-92,9%), showed merino ewes, but taking into account the increased multi-fetus pregnancy in the latter the lambs reared per one ewe to the weaning there were significantly more, which amounted 1,61-2,03 lambs, and in the control it was only 1,15.

The increased multiparous characteristics of sheep are associated with a decrease in the live weight of lambs at birth: from Romanov ewes during the selection of Caucasian sheep to them by 35,4%; from Romanov x Caucasian  crossbreds, with reproductive crossing by 31,1% and back crossing - by 27,9%;  from Caucasian x Romanov hybrids of reproductive crossbreeding by 26,9% compared with less prolific animals of the Caucasian breed. However, the multiparous lambs of the genotype being created have a significantly higher growth rate: from birth to 4 months by 9,0-20,1%; from four to eight months by 30,8-52,3% compared with the merinos.

The production of mutton in live weight per 1 half-blooded ewe increases with reproductive cross-breeding by 74,1-82,7, and with back crossing by 55,8% compared with merinos. The profitability level of production in half-blooded crosses of reproductive (+165, +178%) and back crossing (+137%) is 2,25-2,92 times higher than in merinos (+61).