Repeatability of pig true ileal amino acid digestibility coefficients: Among and within laboratories.

Abstract

Background: When determining true ileal amino acid (AA) digestibility values in the growing pig to calculate digestible indispensable AA score (DIAAS) there are aspects of the protocol, both genetic and environmental, that vary between laboratories.

Objective: The aim was to determine true ileal AA digestibility in nine foods in each of three laboratories (Australasia, Europe and North America) to determine inter-laboratory variability. In each laboratory, three foods were also evaluated twice to determine intra-laboratory variation.

Methods: Each laboratory followed a standardised protocol to determine true ileal AA digestibility for each food. Growing pigs received each food for 7 days and digesta were collected via a cannula at the terminal ileum on days 6 and 7. True ileal AA digestibility coefficients were determined for each food at each laboratory to evaluate inter-laboratory variability. Three foods were evaluated twice in different cohorts of pigs at each laboratory (intra-laboratory variation).

Results: There was no statistically significant effect (P>0.05) of laboratory on the true ileal AA digestibility coefficients for eight of the foods. Differences in AA digestibility were found for wheat bread. The mean coefficient of variation (CV) between laboratories for digestibility of the indispensable AAs was 5.0% with an overall mean for all AAs of 5.5%. For intra-laboratory variability, there were no statistically significant differences (P>0.05) in AA digestibility for any food with mean CVs for each AA within each of the three laboratories for the indispensable AAs of 1.3, 1.1 and 0.9%.

Conclusion: True ileal AA digestibility values determined in the growing pig for the same foods in different laboratories (inter-laboratory variation) do not vary greatly. When a single food was evaluated a second time in the same laboratory, little variation among digestibility values was found.