Abstract
The objective of this study was to identify polymorphisms in the myostatin and leptin genes in Santa Ines (SI) and crossbreed (SI x Dorper) sheep, to verify the effect of these polymorphisms on carcass traits. We evaluated seventy sheep of 8-month-old at the Federal Institute of Espirito Santo, Brazil. Data collected were slaughter weight (SW), hot carcass weight (HCW), cold carcass weight (CCW), loin weight, tenderloin weight and fat thickness (FT). The hot carcass yield (HCY) was calculated by the formula (HCW/SW) x 100. We collected hairs from each animal for DNA extraction by the alkaline protocol. The animals were genotyped for the G>A mutation in nucleotide 9827 of the myostatin gene and for three polymorphisms in exon 3 of the leptin gene, by the PCR-RFLP technique. The amplicons the myostatin and leptin gene were cleaved with restriction enzyme for allelic discrimination. The alleles were recorded for each animal and analysis of variance was performed to check the influence of the mutations on the carcass traits. The mutant allele of the myostatin gene showed association with increased measures of CCW, FT and with reduced HCY. Among the three alleles of the leptin gene, only one showed an effect (increased CCW). The other alleles were not associated with any traits.
Highlights
The Santa Ines is the most popular local breed of Brazil characterized by high adaptive value, reproductive, resistance to gastrointestinal parasites in addition to a good weight development in the tropics (COSTA JÚNIOR et al, 2006)
The polymorphism genotyped in the 3’UTR of the myostatin gene, which is involved in G>A exchange, was found in the population studied
The animals of the Santa Inês breed in the present study did not present any mutation for the myostatin gene
Summary
The Santa Ines is the most popular local breed of Brazil characterized by high adaptive value, reproductive, resistance to gastrointestinal parasites in addition to a good weight development in the tropics (COSTA JÚNIOR et al, 2006) It has been used as maternal lineage at the crossing with specialized breeds in meat production by is adapted the climatic conditions in the tropics. A polymorphism based on a guanine-toadenine transition in the 3’UTR of the myostatin gene was discovered. This mutation generates a miRNA site that inhibits the gene’s translation, so animals that carry this mutation can suffer from muscular hypertrophy (CLOP et al, 2006)
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