| Abstract: | Five N balance studies were conducted to determine the faecal composition and N excretion of feeding raw Lupinus angustifolius seed meal and its fractions for growing rats using a semi-synthetic lactalbumin-based diet as control. Diets were formulated to have equal amounts of energy. The protein was incorporated at the level of 10% bulk and contained unsupplemented lupin seed meal (LMU) and fully supplemented lupin seed meal (LMFS) at 360 g kg−1 diet, aqueous extract non-dialysed (LPAND) at 196 g kg−1 aqueous extract dialysed soluble at pH 7·0 (LPAD) at 148 g kg−1 aqueous extract dialysed insoluble at pH 7·0 (LPADI) at 124 g kg−1, buffer dialysed soluble at pH 7·0 (BUSOL) at 136 g kg−1, buffer dialysed insoluble at pH 7·0 (BUDI) at 119 g kg−1 and lupin meal residue after aqueous and buffer extraction (LMR) at 170 g kg−1 diet. Rats were pair-fed for 10 days with all the above diets which had been supplemented with essential amino acids up to the target requirements for rats. Faecal wet and dry weight were increased in rats fed on LMU, LMPS and LMR diets compared to those obtained from the control diet based on lactalbumin (milk protein) LACT. The higher faecal weight was largely due to water content. The higher faecal N excretion observed in LMU, LMFS, LPAND, LPAD, BUSOL, BUDI and LMR compared to that of LACT diet was significantly lower and thus which was assumed not to be due to a decrease in the digestibility of the dietary protein, which was over 90% as compared to that in the control group. Analysis suggested that an increase in endogenous N excretion is involved in the rise of its excretion in the faeces, and indicates a long-term effect of this seed as a protein and or fibre source in monogastrics. |
