Lipostatic regulation experimental provoked in farmed atlantic salmon (salmo salar L.)

Abstract

The present study was conducted to investigate the influence of various salmon fatty accumulations in the early summer on the growth of Atlantic salmon in the following autumn and if this may be linked to sexual maturation preparation. The effect of varying dietary supplementation treatment on the growth of Atlantic salmon was also studied. During the build-up phase from 21st May to 8th August, the Atlantic salmon was distributed into 3 cages with an initial mean body weight of 1085 g ± 2. Three different pre-diets: T1: 100% original Cod feed, T2: 50% ration of original Cod feed and T3: 100% original Atlantic salmon feed were used in this period. The build-up phase was designed to provoke the varied muscle fat content and body weight in the early summer. Thereafter, in the second experimental period (from 9th August to 6th December), individually marked (Pit-Tag) fish were randomly selected from each build-up group and polled in 12 identical net-pens. Three different autumn diets were supported in randomized block design, which were Control feed T6, Marine feed T4 and Protein feed T5 (Control feed + 2% glutamate/arginine). The influence of different initial muscle fat content in the early summer on the growth rate (SGR and TGC), body weight and muscle fat deposition in the following autumn and if this affects the sexual maturation preparation was determined. We also investigated the effect of different ingredient supplemental diets on the growth of fish. At the end of the build-up phase, fish fed T3 Salmon diet was shown to have a high muscle fat content. During the second experimental period, glutamate/arginine and rapeseed oil supplemental diets had no significant effect on growth rate and feed utilization. However, significant differences were observed within pre-dietary groups. Fish with low initial muscle fat content obtained a significantly higher growth (SGR and TGC) than their counterparts. Both partial compensation and over-compensation III had been achieved in the study. The obtained differences in growth and fat content accumulation could be considered as results of lipostatic regulation, meanwhile that also might be closely linked to the sexually mature preparation. We thus presumed that fish will slow down or even stop their fat accumulation once certain fat and energy reserves have been achieved according to lipostatic regulation and/or sexual maturation.