CYTOGENETIC MONITORING IN SHEEP BREEDING, SELECTION AND reproduction
The article presents the results of the cytogenetic monitoring in the breeding, selection and reproduction of sheep in the ecological conditions of Ukraine. A cytogenetic analysis of sheep with low and high vigor and different levels of fertility was carried out. In the ecological conditions of Ukraine, the individual level of chromosomal abnormalities in all the studied animals of the Tsigai breed and prekos is within the natural background. No translocations were found. Among the violations, such as single and paired fragments, hypo- and hyperploidy (mainly hypoploidy), polyploidy were encountered. The maximum average level of chromosomal abnormalities was found in local lambs (5.5±1.73%). The minimum average level of chromosomal abnormalities (2.0±1.41%) was recorded in lambs with high growth intensity. Among the structural changes, mutations of the chromosomal type prevailed in the 3-year-old group of rams - 0.46%, in the 8-year-old group - 0.59%. Chromatid disturbances were 0.37% and 0.34%, respectively. The average level of chromosomal abnormalities in rams by groups was 0.84±0.14 and 0.93±0.13, respectively. In the group of ewes with low fertility (n = 4), the level of chromosomal abnormalities was 3.5%, which is lower than ewes (n = 7) with high fertility by 0.79%.