Genetic Variation in the Calpastatin Gene and its Association with Growth Traits in Batur Sheep

Abstract

The present study aimed to investigate the association of the CAST genotype and growth traits in Batur sheep. Batur lambs were reared under an intensive feeding system. Bodyweight is measured monthly after weaning until six months of age. Blood representing thirty head were collected, genomic DNA was extracted as samples, and then 200 µl of whole blood samples were used. Specific primers were designed to amplify the CAST gene, samples were sequenced, then the researchers used the BioEdit program to identify any mutation. Calculation of genotypes, gene and allele frequencies, heterozygosities, and Chi-square test was performed. The analysis revealed a total of sixteen polymorphic sites in the CAST coding region. There are four alleles observed (A, G, C, and T), trans-versions at c.92T<G and c.285G>T loci, and transitions at c.214G>A, c.280G>A, c.301C<T, and c.371A>G. One individual disrupted the reading frame in the whole CAST sequenced. The genotype frequency analysis showed the highest predominance of the (TT, GG, CC, and AA) genotypes with frequencies (66.7 %, 62.9 %, 59.3 %, 66.7 %, and 55.6 %) as homozygous. In contrast, the heterozygous (TG, GA, GT, CT, and AG) genotypes were present at lower frequencies (29.6 %, 33.3 %, 37 %, 29.6 %, and 37 %), respectively with four difference alleles (T, G, C, and A). Post-weaning bodyweight till 6-month age of Batur sheep for the heterozygous genotypes at loci (c.92T<G, c.214G>A, c.280G>A, and c.301C<T) was slightly more massive than those carrying homozygous wild-type genotypes (c.285G>T and c.371A>G) with no significant differences (p > 0.5). The lambs with the heterozygous genotype had a significantly higher muscle percentage as a whole, compared to the other genotypes. Polymorphic sites were present in Batur sheep for the first time about the association with the CAST gene. However, the CAST gene might not be a useful marker for developing future selection programs in Batur sheep unless further investigation of the CAST gene and its interactions with other genes involving muscle growth and carcass traits are analyzed through association studies at a large scale.
 Keywords: genetic variation, CAST gene, association, Batur sheep, growth traits