Impact of nutritional programming on the growth, health, and sexual development of bull calves

The growth, health, and reproductive performance of bull calves are important prerequisites for a successful cattle breeding program. Therefore, several attempts have been made to improve these parameters via nutritional programming. Although an increase in energy uptake during the postweaning period (7-8 mo of age) of the calves leads to a faster growing rate, it has no positive effects on sexual development. In contrast, a high-nutrition diet during the prepubertal period (8-20 wk of age) reduced the age at puberty of the bulls and increased the size and/or weight of the testis and the epididymal sperm reserves. This faster sexual development is associated with an increased transient LH peak, which seems 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 the calves are not clear. The sexual development of bull calves depends not only on the nutrition of the calves after birth but also on the feed intake of their mothers during pregnancy. In contrast to the effects of the feed intake of the bull calves, a high-nutrition diet fed to the mother during the first trimester has negative effects on the reproductive performance of their offspring. In conclusion, it has been clearly demonstrated that growth, health, and reproductive performance can be improved by nutritional programming, but further studies are necessary to obtain a better understanding about the mechanisms responsible for this phenomenon.