The ileal amino acid digestibility of different protein sources for early-weaned piglets

Abstract

This study was conducted to determine the apparent amino acid (AA) digestibility of different protein sources for early-weaned piglets. A standard diet plus three diets, in which 20% of the standard diet was substituted with either skimmed milk powder (SMP), fish meal or roasted full fat soya beans (FFS), were used. Piglets were cannulated at 18 days of age and returned to the sow. After weaning at 21 days of age, the piglets were fed ad libitum on a weaning diet. From 30 days of age, they received their respective diets in hourly portions, while ileal digesta was sampled from day 33 to 37. Chromic oxide was used as an indigestible marker. Digestibility values of the protein sources were calculated by difference. Results showed no differences in apparent digestibility values of N and AA between SMP and fish meal, and between fish meal and FFS. However, there was a tendency for AA digestibility in SMP to be higher than in fish meal, and in fish meal to be higher than in FFS (e.g., lysine digestibility of 97.8, 92.0 and 83.7%). The differences in N digestibility between FFS and SMP, on the one hand, and fish meal on the other (15.1 and 11.9 percentage units) were not significant ( P>0.05). High coefficients of variation (CV) were found (21.1, 11.2 and 14.2% for FFS, SMP and fish meal, respectively). The results show that using total AA contents to balance diets could overestimate and hence overrate protein sources with low AA digestibility, and thus underestimate protein sources with high AA digestibility.