STUDY POLYMORPHISMS IN GH1 GENE AND RELATIONSHIP WITH GROWTH PERFORMANCE AND FEED CONVERSION EFFICIENCY IN LOCAL MEAT-TYPE SHEEP IN KARBALA GOVERNORATE

Abstract

Growth rate and feed efficiency are major determinants of profitability in meat-type sheep. This study investigated polymorphisms in exon 2 of the ovine GH1 gene and their associations with growth performance and feed conversion efficiency in 100. GH1 genotypes were determined by PCR-RFLP and confirmed by Sanger sequencing, The locus was polymorphic, with G and A allele frequencies of 0.64 and 0.36 and genotype frequencies of 0.42, 0.44, and 0.14 for GG, GA, and AA, respectively, The observed heterozygosity (0.44) was near to the expected heterozygosity (0.46), PIC was 0.35 and the population conformed to Hardy-Weinberg equilibrium (P=0.67). The study results showed that The initial body weight (BW 0) and final body weight (BW 90±0) reached has been (18.4±2.8) kg and (38.6±4.2) kg, respectively, On days 30 and 60 body weights (BW-30 and BW-60), the weights were (24.8±3.1) kg and (31.5±3.6) kg, respectively. The average daily weight gain (ADG) over the entire period was (224±38) g/day, indicating significant variation in growth performance between the animals. The total dry matter intake (DMI) after 90 days was (82.5±12.4) kg, while the mean feed ratio (FCR) was (4.08±0.64) kg feed/kg weight gain.GG lambs had the highest final body weight (40.2±0.6 kg) and average daily gain (235±5 g/day), followed by GA and AA lambs (P<0.05), but GG lambs had a more favourable feed conversion ratio (3.87±0.08 kg feed/kg gain) than GA and AA lambs (P<0.05),These results indicate that GH1 variation, particularly the G allele, may be useful as a marker for improving growth performance and feed conversion efficiency in local meat-type sheep.