Comparison of the nutritional value of diets containing differentially processed blue sweet lupin seeds or soybean meal for growing pigs

The current study aimed at determining the influence of both grinding intensity and expanding of blue sweet lupin (BSL) on the nutritive value of complex diets for growing pigs as compared with soybean meal-based diet. Four diets were formulated based on soybean meal (SBM, 21% in the diet) or differentially treated BSL (31% in the diet). Treatments of BSL were: ground to pass a 3 mm (CBL), 1 mm (FBL) sieve or ground to 1 mm and subsequently expanded (EBL). Twelve PIC x Danbred pigs (initial BW 20 kg), fitted with a T-cannula at the terminal ileum were used in an incomplete 3 × 4 Latin square design. Coefficients of ileal apparent digestibility (CIAD) and total tract apparent digestibility (CTTAD) of proximate nutrients and non-starch polysaccharides (NSP), and standardized ileal digestibility (SID) of amino acids were determined. The CIAD of organic matter, ether extract and starch was higher (P < 0.05) in SBM diet compared to CBL diet but similar to FBL and EBL diets. The CTTAD of CP was lower (P < 0.05) in CBL and FBL diets compared to SBM diet. The CTTAD of total NSP and their constituents (arabinose and galactose) was higher in all diets containing lupins. In addition, CTTAD of glucose and both, CIAD and CTTAD of glucuronic acids was the highest in EBL diets. The SID of methionine was higher in FBL compared to SBM diet. Similarly, SID of arginine was higher in FBL and EBL diets compared to CBL and SBM diets. The data show that fine grinding intensity and expander treatment can improve the digestive utilization of diets with BSL in growing pigs-at least to similar level as with SBM diet.