Bearden and Fuquay (1992) summarized the effects of inadequate and excessive nutrients on reproductive efficiency. This summary shows that excessive protein and/or energy could have negative effects on reproduction. Often, there are questions by livestock producers who are concerned that excessive dietary nutrients during the last trimester of pregnancy may negatively influence calf birth weights and dystocia. Oklahoma workers summarized the effects of providing either adequate (not excessive) or inadequate amounts of dietary energy and protein on calving difficulty, reproductive performance and calf growth. The research was consistent in suggesting that reducing protein or energy pre-partum had little effect on dystocia rates, even though birth weights were altered in some experiments. Of the nine trials summarized, seven showed that increased energy intakes during the last trimester of gestation did not increase calving difficulty. Producers have commented that supplemental crude protein increases calf birth weight. Of the five studies reviewed, one study showed that excessive protein increased calving difficulty while four other studies did not show any effect on dystocia, birth weight, calf survivability or weaning weight.

Examples of Inadequate or Excessive Dietary Nutrient Intake on Reproduction in Beef Cattle (Bearden and Fuquay, 1992)