Concurrent with increased prolificacy, high sow death losses and replacement rates are serious economic and welfare issues facing producers. Reproductive failure is the most frequent reason for culling sows. Lifetime productivity is characterized by moderate heritability and high phenotypic variance and, as a result, substantial genetic variation is expected to exist in most populations. Traditional selection for sow reproductive longevity results is ineffective due to low heritability and late expression of the trait. The primary goal of this research project was to identify DNA markers associated with reproductive and sow lifetime productivity that can be used in nucleus herds to select for increased lifetime productivity. Incorporation of DNA markers into selection programs is potentially a more practical approach for improving sow lifetime productivity. Using a resource population of crossbred gilts developed at UNL, we explored genetic factors associated with reproductive traits and lifetime productivity. Our work generated the following major research findings:
 From all the traits recorded before breeding, age at puberty was the only one that significantly affected the chance of females would produce a first parity litter.
 Genome-wide association analyses uncovered several regions that have an effect across the reproductive traits.
 DNA markers located on three different chromosomal regions were associated with early expression of puberty that led to up to 1.36 greater number of lifetime parities.
 Genomic prediction values of reproductive traits explained an important proportion of the phenotypic differences when training and prediction was performed in the same data set but negligible for litter size traits when training and genomic prediction were performed in different data sets.
Daniel C. Ciobanu, PhD
Assistant Professor, Molecular Genetics.
A218k Animal Science Bldg.
Department of Animal Science
University of Nebraska-Lincoln
Lincoln, NE 68583-0908
Phone: (402) 472 8066""