SINGLE STRAND CONFORMATIONAL POLYMORPHISM OF ADRβ3 GENE AND ITS ASSOCIATION WITH LIVE PERFOR-MANCE TRAITS IN BARKI SHEEP

The adrenergic receptor β3 (ADRβ3) is the major regulator of lipolysis and homeostasis and predominantly expressed in brown and white adipose tissues (Cannon and Nedergaard, 2004). The ADRβ3 gene which encodes for this receptor was studied as a candidate gene associated with growth traits, body dimensional measurements and conformation indices of Barki sheep. Single strand conformational polymorphism (SSCP) was used to identify the variation in the intron region of ADRβ3 gene for 136 male and female Barki lambs. Eighteen SSCP genotypes representing six alleles (A, B, C, D, E and H) were detected. The frequencies of these alleles were 0.331, 0.184, 0.283, 0.044, 0.073 and 0.084, respectively. The results indicated that ADRβ3 genotype significantly (P ˂ 0.05) affected marketing weight, thigh circumference, body mass index and skeletal muscle index; and also significantly (P ˂ 0.01) affected post-weaning daily gain. Least square means analysis showed that animals with genotypes AA, AC and CC had higher post-weaning daily gain, marketing weight, thigh circumference, body mass index and skeletal muscle index than animals with genotypes CD, CE and CH. In view of the obtained results, molecular marker selection using ADRβ3 gene is warranted to increase post-weaning growth rate, whole-body mass and skeletal muscle mass in Barki sheep and will be of considerable economic value to sheep producer.