Determining the metabolizable energy value of high quality cassava peels in roosters by a regression method

Abstract

The metabolizable energy of high quality cassava peel (HQCP) - a by-product of cassava processing, was investigated in thirty-two 27 weeks old ISA brown roosters (2118.75 ± 255.82 g). High quality cassava peel was obtained from the International Livestock Research Institute, Moniya, Ibadan, and incorporated in a corn-soybean meal grower diet at 5, 10 and 15% of the diet in substitution for glucose monohydrate to create the experimental diets; HQCP-0, HQCP-5, HQCP-10, and HQCP-15, respectively and titanium dioxide included at 0.5% as an inert marker. Roosters were placed in metabolic cages (2 roosters/cage, 4 cages/treatment) and fed the experimental diets for 10 days. Excreta was collected during the last 3 days, dried at 55°C and analyzed for dry matter, nitrogen, gross energy and titanium. Feed consumption was calculated, and nitrogen and energy utilization estimated. The metabolizable energy of the HQCP was estimated as the slope of the regression of metabolizable energy of the diets corrected for glucose contribution, against the inclusion rate of HQCP in the experimental diets. No significant (p > 0.05) treatment effect was observed for feed intake and weight changes of the roosters as well as nitrogen and energy retention. However, apparent metabolizable value of the diets declined significantly (p < 0.05) at 15% inclusion level of HQCP. Linear regression analysis (p < 0.001, r² = 0.90) showed that the metabolizable energy value of high quality cassava peel used in the study was 2.117 ± 0.103 kcal/g for 27 weeks old roosters.