In the present study, the mean difference of optimized and realized
nutrient contents of feed varied between feed companies. Currently,
the feed producers declare feed performance (DE and DP) based on
analyses of raw materials in internal laboratories. Any differences in
models and methodology between feed manufacturing companies
may thus pose a challenge in commercial comparison of feed declarations
influencing the optimized nutrient and energy specification. A
positive mean difference of DP as found for Company 3 in the present
study indicates that DP levels in feed from this company are higher
than declared. Positive mean difference of DE in feed from Companies
4 and 5 similarly suggests higher available nutrient and energy level,
suggestive for a better feed performance than declared under optimal
feeding conditions. Although the number of samples from these two
companies was quite low, the standard deviations of the mean difference
of DE were smaller for these companies. Explanations for this can
be that the samples were taken over a relatively short period, that
there were more sparse feed products from these companies, or that
there were more traditional marine ingredients and less complex feed
recipes in terms of raw material choice in feed from these companies.