Genetic polymorphism of growth hormone gene in native sheep breeds of India

Abstract

Genetic polymorphism of growth hormone gene at locus A1575G and A781G was studied for 9 sheep breeds of different agro-ecological regions of India. A total of 324 random blood samples of Indian sheep breeds were analyzed by PCR- RFLP (Polymerase chain reaction- Restriction fragment length polymorphism) technique. Restriction digestion analysis at A781G locus revealed two allelic variants (A= 0.6016 and B= 0.3983) and two genotypes (AA= 0.2032, AB= 0.7968). At A1575G locus, all individuals were homozygous (CC) in all 9 breeds. The allelic frequency differences for both alleles across the Indian breeds, irrespective of their geographic distribution, colour pattern and utility traits, were statistically non-significant. The average heterozygosity was 0.4712. These findings reveal that substantial level of genetic variation exists at A781G locus and adds substance to search for QTL(quantitative trait locus) for growth trait in Indian sheep breeds.