University of Arkansas, Fayetteville Division of Agriculture


Little is understood about how the diversity of genes, specifically the glucocorticoid receptor (GR) and interleukin-8 receptor (CXCR2), are related to reproductive health and how this affects physical traits in cattle. Glucocorticoid receptors have been positively associated with higher milk yields, lactose content, feed intake, and feed conversion rates. Interleukin-8 genes are part of the innate immune response and help with many aspects of female reproductive health, such as protecting the embryo from the maternal immune system during pregnancy. The objective of this research was to identify polymorphisms in the GR and CXCR2 genes and to associate genotypes between the abovementioned polymorphisms and production traits in crossbred cattle. The hypothesis was that polymorphisms will exist for GR and CXCR2 genes and will be linked to production traits. Blood samples were collected from 94 crossbred cattle over a period of 3 years (2012, 2013, 2014) and the DNA was extracted, amplified, and sent to GeneSeek in Lincoln, Nebraska, to be analyzed and genotyped for single nucleotide polymorphisms (SNP). Phenotypic data, including cow pre-breeding body condition score (BCS) and weight, Julian calving date, calf birth weight, cow weaning BCS and weight, calf weaning weight, calf adjusted 205-day weight, cow efficiency, and hair coat scores (HCS) were collected from the 94 crossbred cattle and analyzed alongside the genotypic results. Significant relationships were determined using t-tests. Single nucleotide polymorphisms were found for the GR and CXCR2 genes and the polymorphisms were significantly related to production traits in cattle. Scientists and breeders could manipulate these genes to produce cattle that are more efficient and possess more desirable production traits.