IMPROVING THE NUTRITIVE-VALUE OF NIGERIAN RUBBER KERNEL (HEVEA-BRAZILIENSIS) PRODUCTS THROUGH PROCESSING .2. APPARENT NUTRIENT AND METABOLIZABLE ENERGY VALUES

A metabolism trial was designed to investigate the effect of method of processing (raw, sun-drying, oven-drying, soaking, autoclaving, and r oasting), rate of inclusion (ROI), and method of estimation (regressio n or single-level assay) on apparent nutrient and metabolizable energy value of full-fat and fat-extracted rubber kernel meals and oil using 264 seven-day-old Ross broiler chicks. The oil and full-fat meals wer e incorporated at levels to provide 40, 80, and 120 g kg(-1) of added oil in the basal diet. Fat-extracted meals were also included at the e quivalent levels in the full-fat meals. Apparent metabolizable energy (AME) values were not significantly influenced by ROI with the values determined by regression being more precise than those estimated by si ngle-level assay. Heat treatment generally improved AME, and for the f ull-fat meals, moist heat-processing (autoclaving or soaking Drier to oven-drying) was more effective than dry-heating (oven-drying and roas ting). The AME of the roasted full-fat was 16.1 MJ kg(-1) dry matter ( DM) while the mean value of soaked and autoclaved full-fat (21.3 MJ kg (-1) DM), was significantly greater than the mean of oven-dried and ro asted full-fat meals (18.7 MJ kg DM). Rubber kernel oil had an AME val ue of 35.3 MJ kg(-1) DM. An improvement in energy and nutritive value brought about by processing suggests inhibition of inherent deleteriou s factors, the specific nature and definite levels of which would requ ire further investigations for effective use of rubber kernel products as feed ingredients for non-ruminants.