“Development of Genetic and Genomic Predictors of Fertility in Argentinean Holstein Cattle.”

The overall aim of the studies described herein was to evaluate genetic variation in cattle fertility traits for development of genetic and genomic predictors in breeding strategies. Results from these experiments suggest that improvements in fertility through genetic selection are a possible approach to increase reproductive efficiency. Experiment 1 evaluated the development of genetic parameters associated with multiple ovulation and embryo transfer schemes in an attempt to assist producers in identifying animals with greater genetic merit for these protocols. This study confirmed that genetic selection of donors or sires appears to be a potential approach to improve efficiency of MOET procedures. Although low heritability would slow the progress, results shown in this work suggest that genetic improvement in fertility by selection for embryo transfer traits is possible. Experiment 2 evaluated fertility traits in Argentinean Holstein cattle in order to develop fertility genetic predictors for utilization in breeding strategies. The dollar fertility index ($F) included age to first calving (AFC) as a measure of initial reproductive performance and calving interval (CI) as an indicator of conception rate and success of early insemination. Values for $F ranged from -$76.6 to $139.4 in the current Holstein population. Results indicated substantial variation in fertility traits, suggesting that genetic selection would be highly effective in improving fertility.