UTILIZATION OF DIETARY ENERGY AND NUTRIENTS FROM SOYA BEAN PRODUCTS BY GROWING PIGS

A metabolism trial with four periods was conducted with 13 gilts to determine apparent digestible energy and nutritive values of extruded full-fat soya beans (FFSB) and of extracted soya bean meal (SBM) and soya bean oil (SBO) either separately or mixed, as affected by rate of inclusion. method of determination, and weight or age of pigs. Each soya bean product was evaluated at levels to provide 40, 80 and 120 g kg-1 added oil in a basal diet. Their digestible energy (DE) content and apparent digestibility of oil (AOD-using two oil analytical methods) and nitrogen were estimated by single-level assay and by regression. Regression values for DE (MJ kg-1 dry matter (DM)) were: SBO, 38.4; FFSB, 18.3; OSBM (SBO plus SBM) 20.4; and SBM, 16.7. Dietary energy values and AOD were linearly related to rate of inclusion of test ingredients. Linear regression models were better than single-level assays, which gave high standard errors. Weight of pig (over the range 32-70 kg) did not affect dietary energy and AOD values of soya bean products. The method of oil analysis adopted could influence data for oil utilization of soya bean products. Although important, AOD may not be the major factor influencing the utilization of full-fat soya beans. The results suggested that soya bean products are variable feed ingredients, the nutritive value of which is influenced by many factors which need be taken into account for the effective use of these products in diet formulation.