Variation in digestibility of protein and lipid among individual Atlantic salmon

Abstract

A group of 60 pit tagged post smolt Atlantic salmon chosen randomly from a pool of 50 families (34 represented), with an initial body weight of 440 g, were reared in a single tank for 56 days. Fish weight gain was 414 g and specific growth rate 1.2% d-1 during the experimental period. Individual apparent digestibility coefficient (ADC) was determined from three faecal samples of each fish (stripping) obtained during the experiment. ADCs mean and standard deviation (SD) for the first stripping (n=57) was 90.8% (SD=1.4%) for protein and 95.0% (SD=1.1%) for lipid; for the second stripping (n=56), 90.0% (SD=1.5%) for protein and 94.8% (SD=1.1%) for lipid, and for the third stripping (n=54) 88.5% (SD=2.5%) for protein and 93.9% (SD=2.0%) for lipid. Intraclass correlations (repeatability) for ADC of lipid varied from 0.24 to 0.5 and of protein from 0.00 to 0.02. These results indicate significant genetic variation in digestibility of lipid in Atlantic salmon, but not for protein. Therefore it should be possible to obtain a favorable genetic gain for ADC of lipid, but not for ADC of protein.