ABSTRACT
In the last decades a series of attempts have been made to improve reproductive performance of bulls via optimizing nutrition. Although an increase in energy uptake during the post-weaning period of calves led to a faster growing rate, it had no positive effects on sexual development. In contrast, a high-nutrition diet during the prepubertal period reduced the age at puberty of the bulls and increased the size/weight of the testis and the epididymal sperm reserves. This faster sexual development was associated with an increased transient LH peak, which seemed to be mediated by an increase in serum IGF-I concentrations. However, the exact mechanisms responsible for the interaction between nutrition and the subsequent development of calves are still not clear. Sexual development of bull calves depends not only on nutrition of the calves after birth but also on the feed intake of their mothers during pregnancy. A high-nutrition diet fed to the mother during the first trimester has negative effects on the reproductive performance of their offspring. In summary, growth, health and reproductive performance can be improved by nutrition, but further studies are necessary to obtain a better understanding about the mechanisms responsible for this phenomenon.(AU)
Subject(s)
Animals , Male , Cattle , Cattle/embryology , Cattle/metabolism , Animal Feed/adverse effects , Animal Feed/analysis , Sexual DevelopmentABSTRACT
In the last decades a series of attempts have been made to improve reproductive performance of bulls via optimizing nutrition. Although an increase in energy uptake during the post-weaning period of calves led to a faster growing rate, it had no positive effects on sexual development. In contrast, a high-nutrition diet during the prepubertal period reduced the age at puberty of the bulls and increased the size/weight of the testis and the epididymal sperm reserves. This faster sexual development was associated with an increased transient LH peak, which seemed to be mediated by an increase in serum IGF-I concentrations. However, the exact mechanisms responsible for the interaction between nutrition and the subsequent development of calves are still not clear. Sexual development of bull calves depends not only on nutrition of the calves after birth but also on the feed intake of their mothers during pregnancy. A high-nutrition diet fed to the mother during the first trimester has negative effects on the reproductive performance of their offspring. In summary, growth, health and reproductive performance can be improved by nutrition, but further studies are necessary to obtain a better understanding about the mechanisms responsible for this phenomenon.