Genotypes Relationship of Growth Hormone Gene Polymorphism with Some Productive and Reproductive Trait in Awassi Sheep

Abstract

      In this study 50 ewes of native Awassi breed aging (2-5) years and their 62-offspring aging from birth to weaning was used and this study was carried out in the Department of Animal Production/Faculty of Agriculture/ Baghdad University, as well as at laboratories of Institute of Genetic Engineering and Biotechnology for Post Graduate Studies through the period from 1/11/2015 to 1/6/2016. The aim of this study was to investigate the genotypes of Growth Hormone (GH) gene and their association with the production, growth and reproductive traits. PCR-RFLP analysis of (GH) (973 bp) showed three various genotypes AA, AG, and GG with frequencies of 26.00, 44.00 and 30.00 respectively, the frequencies of the A and G alleles were 0.52 and 0.48, respectively. Effect of the genotype variation of GH was highly significant on fecundity rate while not significant on the fecundity ratio, as well as on mortality rate in lambs up to weaning. There was a highly significant (p≤ 0.01), effect of GH genotype on weight of lambs at birth and their weight gain at weaning, body length and chest circumference were also significantly affected in relation with different GH genotypes. The results of this study showed that the daily and total milk production as well as length of lactation periods of Awassi ewes also varied in relation with GH genotypes and in favor of ewes with genotype hybrid AG, while milk components were not significantly affected with variation of GH genotypes unless for proportion of milk fat (p≤ 0.05), in ewes with  genotype GG. In conclusion, the study of gene expression of GH gene could be open interesting prospects for future selection program and also improvement strategies to sheep to maximize the economic income of the election and breeding genotypes that have achieved the best fecundity and milk production.