The use of genetic markers to improve sow productive life and genetic abnormalities

The driving force behind using molecular genetics in livestock selection programs is to improve the profitability of not only the genetic supplier but also their customers using the product. Traditional quantitative genetics have greatly helped the geneticists improve traits with higher heritabilities, but there is still room for advancements, especially in traits that are measured late in life, measured in only one sex, and traits with lower heritabilities. Two such traits that could benefit from the identification and use of molecular markers are genetic defects and sow reproductive life, or the length of time that a sow remains productive in the breeding herd. The studies presented in this dissertation identify current culling reasons of commercial sows, the identification of genetic markers in growth pathways, genetic markers and their associations with sow productive life, and the use of genetic markers to try to isolate the specific genetic defect causing extra digits on pigs.;Analysis of removal reasons for commercial sows revealed that the culling reasons for sows in early parities were for reproductive and locomotive failure, while the main reported reason that sows in more advanced parities were culled was old age. The genetic mapping paper identified single nucleotide polymorphisms (SNPs) in six candidate genes for growth/longevity. These genetic markers were then incorporated with additional markers in research pertaining to genetic markers from growth related pathways and their association with sow productive life. Though no marker suggested that it was causative as none caused an amino acid change, the genetic markers for C-C chemokine receptor 7 (CCR7) and CPT1A showed the clearest and most consistent associations, regardless of analyses attempted, with sow productive life. Additionally, CPT1A and IGFBP1 both were significantly associated with reproductive performance traits such as the total number of pigs born or the number of pigs born alive. The use of molecular genetics to identify the causative mutation pertaining to pigs having extra digits was not as successful. The results presented herein will enhance producers\u27 abilities to increase the financial well being of their operations with reduced financial losses due to genetic defects and poor sow productive life