Abstract

Yousef Mehmannavaz*, Cyrus Amirinia, Mortaza Bonyadi and Rasoul Vaez Torshizi

The effects of Insulin-Like Growth Factor-1 polymorphism were examined on milk production traits and genetic trends in the Iranian Holstein bulls. A total of 282 bulls were genotyped for SnaBI restriction site in the 5' flanking region of IGF-1 by applying PCR-RFLP method. The allele frequencies for C and T alleles were 0.562 and 0.438, respectively. The results indicated that genetic variants at the 5'-noncoding region of the bovine IGF-1 gene had a marked effect on estimated breeding values of milk (EBVM) and fat yields (EBVF). The heterozygous bulls (CT genotype) had higher EBVM and EBVF than homozygous bulls (P < 0.1) . The average substitution effects of alleles were not significant for none of studied traits (P > 0.1). The studied polymorphism of IGF-1 showed no significant association with genetic trends of milk related traits (P > 0.1). These results suggest that allelic interaction in IGF-1 polymorphism as over dominance and might be effectiveness in animal improving by crossbreeding.