Feed is the largest single cost in salmon production, the cost being
NOK 7.80–8.88 per kg feed in Norway in the period 2008–2011 with an accompanying economical feed conversion of 1.24–1.35. This constituted
47.3%–49.7% of production costs of slaughtered salmon in
the same period . Efficient
feed will contribute to the profitability for the producer, as well as,
reduce the environmental effects through reduced carbon footprint
and lower nutrient effluents to the marine environment from feces
(Hognes et al., 2011). The present finding of increased fat digestibility
of nearly 2 percentage points with high performance feed suggests
that there is a potential for digestion of oils in feeds used in
industrial salmon farming. Environmental changes have influence
on feed intake (Remen et al., 2012), and it might be possible that
feed performance also can be affected by environmental changes.
Water temperature was in fact found to influence apparent fat digestibility
in the present study. The methods described in the present
study might be applied to monitor and document feed efficiency in
commercial salmon production, and the digestibility measurements
can be used to identify factors which negatively influence feed performance.
Feed conversion has traditionally been used to monitor growth
and biomass development in salmon farming. The precision in such
monitoring of biomass has been described as poor Monitoring feed digestibility, and consequently the realized DE
and DP may be used as a supplement and an independent validation
to correct feed conversion and thereby improve biomass monitoring