The results indicated that the overall realized levels of both DE and
DP are high, lower somewhat than overall optimized levels, and also
quite variable over time. There is obviously an array of biotic and abiotic
factors that may influence the digestibility assessments in fish. Moreover,
deviations may also originate from differences in model used to
determine digestible protein and fat compared to the optimized values
given by feed manufacturers. Nevertheless, the relative differences between
feed companies will be independent of such model differences.
In the present study, starch was included in the calculation of realized
DE with a defined digestibility of 65% and at a fixed level (8 g/100 g feed).