Date of Graduation


Document Type


Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level



Animal Science


Rosenkrans, Charles

Committee Member/Reader

Powell, Jeremy

Committee Member/Second Reader

Thomas, Lauren


The objective of this thesis was to identify polymorphisms in the glucocorticoid receptor (GR) and interleukin-8 receptor (CXCR2) genes and to associate genotypes between the above mentioned 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. 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 reproduction health, such as protecting the embryo from the maternal immune system during pregnancy. Despite these things, very little is known about how GR and CXCR2 gene polymorphisms affect phenotypes in cattle. Blood samples were collected from ninety-four crossbred cattle over a period of three 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 was collected from the ninety-four crossbred cattle and analyzed alongside the genotypic results, including: cow pre-breeding 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 HCS. Significant relationships were determined using t-tests. It is expected that SNPs will be found for the GR and CXCR2 genes and that these polymorphisms will be significantly related to the production traits in cattle. Scientists and breeders could manipulate these genes to produce cattle that are more efficient and possess more desirable production traits.


polymorphism, genetics, glucocorticoid receptor, agriculture, meat production