Poultry No. 1573 The replacement value of betaine for DL-methionine and Choline in broiler diets

Especially in times of high raw material prices as a result of limited availability of feed ingredients nutritionist look for ways to keep feed cost as low as possible. Part of this discussion is whether certain ingredients can be replaced by others while avoiding impairments of performance. This discussion sometimes includes the question whether supplemental methionine can be replaced by betaine. Use of supplemental methionine, choline and betaine is common in broiler diets. Biochemically, all three compounds can act as methyl group donors. Figure 1 illustrates metabolic pathways connecting choline, betaine and methionine. This chart shows that choline is transformed to betaine which can then deliver a CH3-group for methylation reactions. One of those reactions is the methylation of homocysteine to methionine. This reaction occurs as part of the homocysteine cycle, which continues by transferring the methyl group further and yielding homocysteine again. Thus, there is no net yield of methionine from this cycle, since it only functions to transport a methyl group.