Choline Supplementation of Layer Diets Containing Soybean Meal or Rapeseed Meal as Protein Supplement

White Leghorn pullets were fed laying diets containing soybean meal or rapeseed meal as the source of supplementary protein and with or without 1,000 mg/kg of supplementary choline. Egg production was higher with soybean meal than with rapeseed meal but was unaffected by choline supplementation of the diets. Average egg weights were similar under all treatments. The yolk represented a larger proportion of the egg meat when soybean was the protein supplement. The addition of choline did not affect the relative weights of yolk and albumen with either the soybean or the rapeseed meal diet. The livers of the birds fed soybean meal contained a higher percentage of fat than did the livers of birds fed rapeseed meal. When choline was added to the diets the concentrations of fat in the liver were reduced by 23.5 and 28.2% in the birds fed the soybean meal and rapeseed meal, respectively. Incidence and causes of mortality were unaffected by the dietary treatments imposed.