Polymorphisms in growth hormone (GH) and insulin-like growth factor-1 (IGF-1) gene and their association with growth traits in beetal goat

Abstract

Beetal is one of the most famous goat breed of Pakistan which is also present in parts of Indian Punjab. It is popular for its larger body size, higher body weight, and good ability to produce milk. In current study, polymorphism in Growth Hormone (GH) and Insulin-like Growth Factor-1 (IGF-1) genes and their association with growth-related traits were studied in Beetal goat. On the basis of previously reported mutations, a set of 7 primer pairs were designed to screen PCR-RFLP based polymorphisms in 60 random selected Beetal goats varying in body weight. The IGF-1 gene was found polymorphic and following three genotypes (AA, AB, and BB) were detected in tested animals with the frequency of mutant (B) and wild-type (A) alleles as 0.35 and 0.65 respectively. Homozygous carrier genotype (BB) was significantly associated (P<0.05) with higher body weight (47.13±0.78kg) followed by heterozygous carrier (BB) and wild-type (AA) genotype associated with 40.45±0.31kg and 38.18±0.37kg body weight respectively. Additionally, maximum wither height and body length were observed in BB (32.25 ± 0.33, 31.93±0.27 inches) genotype followed by AB (31.93±0.27, 31.16±0.35) and AA (31.62±0.68, 30.87±0.86) genotype. Moreover, maximum heart girth was also observed in BB (33.65±0.11) genotype. All known point mutations of GH gene were found monomorphic in the tested animals. Upon sequencing of GH gene, one non-synonymous SNP was identified in exon 2 at 825bp position that caused a change of amino acid Threonine into Alanine. And likewise one insertion variant in intron 4 was observed at position 1546bp in this gene. The results showed that homozygous carrier animals, having BB genotype in IGF-1 gene, were having the highest values for growth traits suggesting the additive effects of mutant (B) allele on growth traits in this breed. On the basis of our results it is suggested that the identified markers can be used in marker-assisted-selection (MAS) in Beetal goat.