Nutritional and management strategies for the prevention of fatty liver in dairy cattle.

Fatty liver occurs in dairy cattle during periods of elevated blood non-esterified fatty acids (NEFAs). Elevated blood NEFAs are associated with hormonal changes at parturition and negative energy balance. Approaches for preventing fatty liver include inhibition of fatty acid mobilization from adipose tissues and altering hepatic metabolism to enhance fatty acid oxidation or export as a constituent of very low-density lipoproteins (VLDL). Nutritional and management strategies to implement these approaches have been examined. Increasing energy density of diet, either by increasing non-fiber carbohydrate or fat, has failed to prevent fatty liver. Two nutritional supplements, ruminally-protected choline and propylene glycol, have proven effective at preventing fatty liver. Choline probably enhances hepatic VLDL secretion. Propylene glycol most likely reduces fatty acid mobilization from adipose tissue. Shortening or eliminating the dry period is a management strategy that reduces the magnitude of negative energy balance after calving and triglyceride accumulation in the liver.