The compensatory growth response of the Atlantic cod: effects of nutritional history

Abstract

The effects of different combinations of nutritional background, feeding regimes and dietary compositions on growth responses of the Atlantic cod have been examined Alternating short periods (1-3 weeks) of food deprivation with unlimited prowslon of food depressed growth below that of controls, but cod that were fed on alternate weeks (1 1) were larger than those that were exposed to 2 or 3 week periods of deprlvahon and feeding (2 2 or 3 3) Thus, periods of food deprwatmn of short duration were insufficient to reduce any marked compensatory growth response When cod were deprived of food for longer periods a compensatory growth response was observed On receiving excess food supplies following 8 weeks of food deprivation the fish grew more rapidly than the controls and had completely recovered body weight within 12 weeks The greatest compensatory growth response was shown by cod in poor condition (lowest condition factor), because at the end of an 18 week growth trial there were no differences In body weight between fish irrespectwe of their initial condition Both sexes displayed a compensatory growth response

Energy dilution with α-cellulose in diets for Atlantic cod (Gadus morhua L.) juveniles — Effects on growth, feed intake, liver size and digestibility of nutrients

“…Ergo, growth was not reduced even though it resulted in lower feed utilization and protein retention. In accordance with the idea that protein growth in animals most likely is regulated through control of food intake (Webster, 1993;Jobling et al, 1994), but energy may be consumed in excess, that means that fat deposition is much less strictly regulated. Based on the appearance and function of the cod GIT, it is classified among the omnivorous species.…”

“…The market value for cod liver is not as high as the market value for cod muscle, therefore it is desirable that cod use protein for muscle growth and reduce liver growth. Liver size can be reduced by starvation (Hemre et al, 1992;Jobling et al, 1994;Karlsen et al, 1994) and lower feeding frequencies (Dos Santos et al, 1993). To reduce feeding to near starvation will result in reduced muscle growth, which will not be economically for the farmer.…”

“…The same strategy will however not function for cod, as this species stores all surplus energy in the liver. Researchers have shown that a high fat content in cod feed gives enlarged liver Lie et al, 1988;Jobling et al, 1991;Hemre et al, 1992;Jobling et al, 1994;Morais et al, 2001;Rosenlund et al, 2004;Karlsen et al, 2006). Also increased dietary starch seems to increase fat and glycogen deposition in liver (Hemre et al, 1989).…”

“…Experiments with cod have shown that there is no gain in exceeding one large meal every 24 hour (Hansen et al, 2006). Atlantic cod have a flexible gastro intestinal tract (GIT), which can be filled to huge volumes when feeding frequencies are low, hence cod will maintain good somatic growth and liver growth (Jobling et al, 1994). That could be why a specific strategy to manipulate the energy deposit in cod, with non-digestible fibre in feed, might lead to success.…”

“…There might be environmental or individual variations that we do not know about. It is known that protein growth in animals is most likely strongly regulated through control of food intake (Webster, 1993;Jobling et al, 1994), foreseen that both protein and amino acid requirements are met. Thus, energy may be consumed in excess, resulting in excess fat deposition and thereby increased liver sizes in cod.…”