Nutritional Management of Transition Dairy Cows: Strategies to Optimize Metabolic Health

During the transition period, dairy cows undergo large metabolic adaptations in glucose, fatty acid, and mineral metabolism to support lactation and avoid metabolic dysfunction. The practical goal of nutritional management during this timeframe is to support these metabolic adaptations. The National Research Council addressed nutritional management of transition cows for the first time in 2001; however, a substantial amount of research has been reported since this publication was released. Results support 2-group nutritional strategies for dry cows to minimize overfeeding of nutrients during the early dry period but increase nutrient supply to facilitate metabolic adaptation to lactation during the late dry period. Increasing the amount of energy supplied through dietary carbohydrate during the prepartum period results in generally positive effects on metabolism and performance of transition cows. Recent research, however, suggests that the form of that carbohydrate (i.e., starch vs. highly digestible neutral detergent fiber) may be of lesser importance. Attempts to increase energy supply by feeding dietary fat sources or decrease energy expenditure by supplying specific fatty acids such as trans-10, cis-12 conjugated linoleic acid to decrease milk fat output during early lactation do not decrease the release of nonesterified fatty acids (NEFA) from adipose tissue. Although the view that nutritional means have limited ability to enhance hepatic export of NEFA as triglycerides in lipoproteins in ruminants has become dogma, recent evidence suggests that nutrients such as choline or specific fatty acids may enhance this process in transi-