Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2009
Publication Date: 4/1/2010
Citation: Looper, M.L., Black, S.G., Reiter, S.T., Okimoto, R., Johnson, Z.B., Brown, M.A., Rosenkrans, C.F. 2010. Identification of polymorphisms in the enhancer region of the bovine prolactin gene and association with fertility in beef cows. Professional Animal Scientist. 26:103-108. Interpretive Summary: Fertility of the cowherd is important to the profitability of beef production. Use of traditional selection techniques for reproductive traits in cattle is slow, usually requiring several years to produce desired changes within a herd. However, use of genetic markers such as single nucleotide polymorphisms (SNP) can accelerate the selection of cattle that are more productive on toxic tall fescue. Scientists from ARS in Booneville, AR, and El Reno, OK and University of Arkansas personnel identified SNPs in the enhancer region of the prolactin gene and determined the association of these SNPs with fertility in beef cows. Polymorphisms of the prolactin promoter were associated with calving rate, diameter of the largest follicle and Julian calving date. These results provide information that suggests identification of cows with specific genotypes within the enhancer region of prolactin gene can assist beef producers in selection of cows that may have increased fertility.
Technical Abstract: Objectives were to investigate the polymorphic nature of the enhancer region of the bovine prolactin (PRL) gene and determine the association of these polymorphisms with fertility in beef cows. Primers were designed to amplify a 500 base pair fragment 892 to 1392 bases upstream of the bovine PRL gene. Two single nucleotide polymorphisms (SNP) were identified at positions –1286 (cytosine to thymine; c1286t) and –1161 (adenine to guanine; a1161g). In the Discovery population, genomic DNA was obtained from purebred Angus, purebred Brahman, Angus x Brahman and Brahman x Angus cows. Cows were assigned to graze either common bermudagrass (CB) or toxic endophyte-infected tall fescue (EI) for their lifetime. Lifetime calving rate, and weight and hip height of calves at weaning during cow lifetime were recorded. In the Validation population, genomic DNA was collected from crossbred Angus cows in either low (BCS = 4.3) or moderate (BCS = 6.1) body condition (BC) at breeding. Calving rate, diameter of the largest follicle, and Julian calving date were determined. In the Discovery population, homozygous thymine cows at c1286t and grazing EI had reduced (P < 0.10) calving rates during their lifetime when compared with all other genotypes grazing either forage type. Cows in low BC and either heterozygous or homozygous for the minor allele of the a1161g genotype calved 22 d later (P = 0.03) in the year than all other cows in the Validation population. Identification of cows with specific genotypes within the enhancer region of PRL gene can assist beef producers in selection of cows that may have increased fertility.