Continuous feeding of over 120,000 units of vitamin D per cow per day can be harmful. Rations that contain 350 units of vitamin E per cow per day, with at least one-half of that amount coming from supplements, should be adequate for high producing and early lactation cows. Research from Germany suggested that supplementation with beta-carotene, a vitamin A precursor, may reduce services per conception and increase estrus intensity and pregnancy rates. However, some U.S. researchers found no improvement in reproductive performance. However, adequate vitamin A in the diet is important.
Nutrition is an important component of a sound reproduction program.
A good dry cow nutrition and management program can have a profound effect on your herd's reproductive efficiency. Feed energy to achieve proper body condition at calving and to minimize the severity and duration of negative energy balance in early lactation. Feed protein according to level of production, and also consider the degradability of the protein ingredients you use. The ration should also provide proper levels of macro- and microminerals and vitamins. Remember, though, that nutrition is only one component of your reproduction program.