Nutritional Modulation of Reproductive Potential in Dairy Bulls
Abstract
Holstein bull calves often reach AI centers in suboptimal body condition. Early-life nutrition is reported to increase reproductive performance in beef bulls. The general aim of this thesis was to determine effects of early-life nutrition on reproductive performance of Holstein bulls. We hypothesized that Holstein bull calves on high-nutrition diets during early-life will have larger testes, greater sperm production, and be younger at puberty than those on low-nutrition diets. We determined that bulls fed the high-nutrition diet from 2 to 31 wk were younger at puberty, had larger testes and had higher concentrations of circulating IGF-I than low-nutrition bulls. Furthermore, early-life nutritional modulation did not alter semen quality. The high-nutrition bulls had more proliferating and differentiating Sertoli cells earlier in life than low-nutrition bulls and IGF-I promoted proliferation of bovine Sertoli cells in culture. Overall we demonstrated that IGF-I has important roles in bovine reproduction and we identified key periods during bull development where it appeared that nutritional modulation affected testes development. Therefore, nutritional modulation can be recommended as a management tool to improve reproductive potential of AI bulls. In addition, we inferred that nutritional modulation may serve as a model for studying mechanisms controlling reproductive development in bulls.
Description
Keywords
Veterinary Science
Citation
Dance, A. (2016). Nutritional Modulation of Reproductive Potential in Dairy Bulls (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27153