The bottom line of the project was that the effects of factors like bulls, A.I. technicians, month of semen collection, month of breeding, age of cow and breeding interval length were small. After they were accounted for, large differences in conception results between herds remained. Nutrition is cited with increasing frequency as a cause of poor reproduction. Each must be considered in herd evaluation. However, for the purposes of this discussion, we'll concentrate on new research and ideas on the effects of protein nutrition on reproductive performance.
Protein is a critical nutrient in the dairy ration.
Adequate amounts must be provided to maximize milk production. However, the results of several recent experiments suggest that concentrations of dietary protein thought to be necessary for maximum production may reduce fertility. Days open was increased in all but one study which reported this information. Unfortunately most of these studies did not involve enough cows to accurately determine the effect of protein nutrition on reproduction. More research will be needed to completely understand the relationship.