Dairy producers and their nutrition advisers have an ever-expanding list of supplements that can be considered when formulating diets. These products include modifiers of rumen fermentation, silage additives, protected nutrients and modulators of nutrient metabolism.

The last publication of the Nutrient Requirements of Dairy Cattle did not include choline as a required nutrient for dry or lactating cows, citing the need for more research. Since that publication, there has been considerable research on choline for dairy cows, including 13 university studies focusing on transition cows.

The transition period for dairy cows is often defined as three weeks prior to calving until three weeks after calving. During this time, the cow experiences dramatic changes in feed intake, nutritional requirements and physiological status that affect nutrient balances, milk yield and composition, health and reproductive performance.

Etiology of fatty liver and ketosis Fatty liver syndrome and ketosis are metabolic disorders that result from intense fat mobilization during hormonal changes and negative energy balance associated with the transition period. The liver is an extremely important metabolic organ in transition dairy cows.