GHRH|HaeIII Gene Polymorphism in Dairy and Beef Cattle at National Livestock Breeding Centers

Abstract

This study was aimed to identify polymorphism of growth hormone releasing hormone (GHRH) gene in 89 heads of Holstein-Friesian (HF) dairy cattle from Lembang Artificial Insemination Center/LAIC (17 bulls), Singosari Artificial Insemination Center/SAIC (32 bulls), and Cipelang Livestock Embryo Center/CLEC (40 cows); as well as in 4 breeds of female beef cattle from CLEC for comparison, providing Simmental (13 cows), Limousin (14 cows), Brahman (5 cows), and Angus (5 cows). This study used PCR-RFLP method by using HaeIII restriction enzyme. The enzyme cut the GHRH gene at nucleotides of GG|CC at the base positions of 118, 312, and 406 and produced 4 fragments of 118, 194, 94, and 45 bp respectively.  Genotyping the GHRH gene produced two types of allele, namely A (312, 94, and 45 bp) and B (194, 118, 94, and 45 bp). These two alleles resulted in three types of genotype, namely AA (312, 94, and 45 bp), AB (312, 194, 118, 94, and 45 bp), and BB (194, 118, 94, and 45 bp).  Frequency of the B allele was dominant to the A allele. Chi-Square analysis showed that all of HF dairy and beef cattle observed were in Hardy-Weinberg equilibrium (X² < X²_(0.05)). The highest heterozygosity value was 0.471 for HF bulls in LAIC, while the lowest one was for HF bulls in SAIC. Heterozygosity values in Simmental and Limousin cattles were higher than that of in HF cattle. The GHRH gene in HF and beef cattle was polymorphic, the exception was for Brahman with the only B allele. This result will improve the understanding of the polymorphism of GHRH gene in dairy and beef cattle.