Markers within the regulatory region of the growth hormone receptor gene and their association with milk-related traits in Holsteins

We studied sequence variations in the regulatory region of the bovine growt h hormone receptor gene. A polymerase chain reaction (PCR)-based method for detecting Alul, Accl, and Stul restriction fragment length polymorphisms ( RFLPs) In the 5' flanking region of the bovine growth hormone receptor gene was developed and tested for association with milk-related traits in Holst ein bulls. Allele frequencies of the polymorphisms in two groups of Holstei n progeny-tested bulls born from 1950 to 1970 and in the 1980s, respectivel y, were estimated. The allele frequency of the Alul(-) allele was 0.63 and 0.42 in the bulls from 1950 to 1970 and in the 1980s, respectively. The fre quency of the Stul(-) allele was 0.14 and 0.07 in the two respective bull g roups. Allele frequency for Accl(-) allele was about 0.22 in both bull grou ps. The differences in allele frequencies for the Alul polymorphism in the two bull groups were significantly different (P less than or equal to .005) , The Alul(+/+) bulls had a higher estimated breeding value (EBV) for fat ( P less than or equal to .016) than Alul(-/-) bulls. The average effect of a llele substitution for the Alul polymorphism was +/-8 for fat EBV, The Alul polymorphism could be further evaluated for use in marker-assisted selecti on in dairy cattle.