Variation in Estimates of the Metabolizable Energy Value of Rapeseed Meal Determined with Chickens of Different Ages

Experiments were conducted to study the metabolizable energy (M.E.) value of rapeseed meal for chickens of different ages. Using laying pullets of three genetic sources, average M.E. values of 2390, 2570 and 2710 cal./gm. were obtained for one sample of rapeseed meal. Three-week old chicks gave an M.E. value of 1465 cal./gm. for the same meal. In another assay, the M.E. value of a second meal was estimated to be 2020 and 1510 cal./gm. for laying pullets and 3-week old chicks respectively. M.E. values of diets containing soybean or one of five different rapeseed meals were determined weekly with chicks to 5 weeks of age. The M.E. value of the soybean meal diet remained relatively constant over the period, whereas M.E. values of the rapeseed meal diets progressively declined to approximately 92% of the values estimated at 1 week of age.