Choline Concentration and Availability in Rapeseed Meal

Abstract

Three rapeseed meals were analyzed and found to contain 4650, 5060, and 5720 mg choline per kilogram, respectively. Three broiler diets formulated with 20% of the respective rapeseed meals, and each containing in excess of 1500 mg choline per kilogram, did not promote as rapid growth as did a control soybean meal diet containing 1000 mg choline per kilogram. Incidence of perosis was higher with the rapeseed meal diets than with the soybean meal diets. Addition of choline to the soybean meal diet affected neither growth nor incidence of perosis in the birds fed this diet. Supplementary choline increased growth and decreased incidence of perosis in the birds fed the rapeseed meal diets. In a second experiment to study availability of choline from rapeseed meal, chicks were fed a diet containing 28% rapeseed meal and 2310 mg choline per kilogram or a soybean meal diet supplemented with choline to provide a total of 2110 mg choline per kilogram. The freeze-dried contents of the lower intestine contained 4.92 mg choline per gram from the rapeseed meal-fed chicks and 2.45 mg/g from the soybean meal-fed chicks. The results of the third experiment showed that unabsorbed choline in the intestine was associated with an increase in bacterial production of trimethylamine. The caecal contents of chicks fed 28% of dietary rapeseed meal contained significantly more trimethylamine than those of chicks fed a control soybean meal diet although both diets contained 2310 mg choline per kilogram.