Diet formulation recommendations for transition cows vary widely due to conflicting experimental results, wide variation in feeding programs among well-managed herds, and lack of understanding of the effects of digestion characteristics of feeds on animal response. Physiological changes over the transition period greatly affect feed intake response to diet. Application of a new theory of feed intake control can be used to understand the effects of diet on feed intake of transition cows. The basic premise of the theory is that feeding behavior is controlled by the oxidation of fuels in the liver; increased oxidation results in a satiety signal decreasing meal size, and decreased oxidation results in a hunger signal causing an eating response. Fat mobilization in the transition period increases oxidation in the liver, likely suppressing feed intake. Considerations to control mobilization of fat reserves and increase feed intake of cows after calving are discussed. Also discussed is the importance ofmaintaining gut fill during this period to maintain buffering, prevent displaced abomasum, and to extend the supply of absorbed fuels when intake decreases at calving. Understanding the function of feeds beyond their energy and nutrient concentrations will help to optimize diets for transition cows.
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