Effect of feed composition and feeding
frequency on growth, feed utilization and nutrient retention in juvenile
Atlantic cod, Gadus morhua L.
G.
Rosenlund, Ø. Karlsen, K. Tveit, A. Mangor-Jensen, G.-I. Hemre-2004
Aquaculture
Nutrition, 10(6): 371-378
Abstract :
Juvenile Atlantic cod (Gadus morhua) were fed extruded feeds
formulated to contain 360-660 g kg-1 protein, 80-280 g kg-1
lipid and 80-180 g kg-1 starch at feeding frequencies
of either once per day or every second day to satiation. The trial was
conducted at 8 °C and lasted for 28 weeks during which fish were
weighed five times at regular intervals. Sampling for proximate analysis was
performed at the start, after 12 weeks and at the end of the trial.
Fish grew from an average weight of 192 g to between 750 and 866 g,
with growth being negatively affected by low dietary protein concentration.
High dietary starch concentrations had some negative effects on growth,
whereas changes in dietary fat concentration had no significant effect on
growth. Liver indices (at the end of the experiment) varied between 80 and
170 g kg-1, and there was a negative correlation
between the ratio of protein to fat and liver index. Feed conversion ratio
(FCR) ranged between 0.74 and 0.88, and feed utilization improved with
increasing concentrations of dietary protein and fat. Increasing dietary
starch concentrations resulted in poorer feed utilization. To achieve good
growth and protein retention, and avoid excessive liver size in juvenile
cod, feeds should contain 500-600 g kg-1 crude protein,
130-200 g kg-1 lipid and <150 g kg-1
starch.
(Nutreco Aquaculture Research Centre AS,
PO Box 48, N-4001 Stavanger, Norway. E-mail: grethe.rosenlund@nutreco.com)