The role of micronutrients in high-yielding dairy ruminants: Choline and vitamin E

This review addresses the potential role of antioxidants and methyl-group sources in optimising the metabolic health of dairy ruminants. The productivity of high-yielding dairy cows has increased over the past 40 years and the milk yield has doubled. Such increases in milk production have been observed not only in dairy cows but also to some extent in other dairy ruminants such as ewes, goats and buffaloes (Bubalus bubalis). As a consequence, in all specialized dairy ruminants it is essential to optimize the macro and micro-nutrient supply, especially during the most critical period in the animals' production cycle i.e. from parturition until the peak of lactation. In this critical phase, an array of factors can enhance the balance between the intake and demand for nutrients, although the availability and supply of the selected micronutrients is also important. The supplementation of dietary antioxidants or boosting the endogenous methyl group status, via vitamin E, selenium and choline are proposed as possible strategies in maintaining stable metabolic health and optimising milk production.