The choline requirement of broiler chicks during the seventh week of life

Male crossbred chicks were used to quantify the choline requirement and choline-sparing value of methionine and betaine for broiler chicks during the seventh week of life. The sulfur amino acid (SAA) requirement of male and female chicks was also determined. In all assays a crystalline amino acid diet containing 14.9% protein equivalent and 3400 kcal. M.E./kg, was employed. Increasing increments (0.08%) of SAA (equal mixture of DL-methionine and L-cystine) were fed from 0.38 to 0.70% of the diet. Least squares analysis indicated SAA requirements for maximal weight gain of 0.61 and 0.62% of the diet for males and females, respectively. The choline requirement was determined by feeding six levels of choline in the presence of 0.62% SAA. Gain but not gain/feed responded linearly to choline addition. Least squares analysis of gain indicated a dietary choline requirement of 358 p.p.m. of 30.6 mg./day. The choline-replacement value of methionine and betaine was found to be minimal.