THE ILEAL AMINO-ACID DIGESTIBILITY OF DIFFERENT PROTEIN-SOURCES FOR EARLY-WEANED PIGLETS

This study was conducted to determine the apparent amino acid (AA) dig estibility of different protein sources for early-weaned piglets. A st andard diet plus three diets, in which 20% of the standard diet was su bstituted with either skimmed milk powder (SMP), fish meal or roasted full fat soya beans (FFS), were used. Piglets were cannulated at 18 da ys of age and returned to the sow. After weaning at 21 days of age, th e piglets were fed ad libitum on a weaning diet. From 30 days of age, they received their respective diets in hourly portions, while ileal d igesta was sampled from day 33 to 37. Chromic oxide was used as an ind igestible marker. Digestibility values of the protein sources were cal culated by difference. Results showed no differences in apparent diges tibility values of N and AA between SMP and fish meal, and between fis h 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 diff erences in N digestibility between FFS and SMP, on the one hand, and f ish meal on the other (15.1 and 11.9 percentage units) were not signif icant (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 result s show that using total AA contents to balance diets could overestimat e and hence overrate protein sources with low AA digestibility, and th us underestimate protein sources with high AA digestibility. (C) 1998 Elsevier Science B.V. All rights reserved.