Lack of Association between Somatotropin Receptor Gene Polymorphism and Birth Weight of Iranian Indigenous Sistani Cattle

The objective of the present study was to determine polymorphism within the promoter region of somato-tropin receptor genes in indigenous Sistani cattle (Bos indicus) and associations between this polymorphism and breeding value of birth weight. The pedigree structure was included by considering 1173 animals with 600 progeny birth weight data obtained from a Zhark breeding station in Sistan and Baluchistan. Heritabil-ity was estimated for birth weight using different univariate models with the derivative-free approach of restricted maximum likelihood algorithm (DFREML). The average weight of each birth was 23.9 ± 3.16 kg. The effects of non-genetic factors were significant (P < 0.01) for birth weight. Direct heritabilities (h2) in single trait analyses were 0.31 ± 0.06. Genomic DNA was isolated from blood and semen using conven-tional methods. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assays were used to genotype this candidate gene in 72 individuals with the birth weight record. The observed al-lele size was similar to that reported in the literature. The Sistani cattle showed higher frequency of alleles ALuI (+) than ALuI (-) in population. Statistical analysis was conducted to test the association of this poly-morphism with the breeding value of birth weight data. There was not significant association between pro-ducing genotypes and birth weight trait. Future research on another candidate gene and growth trait strongly is encouraged to deep in the understanding of growth pattern in this breed.