Sissel Albrektsen

Ascorbyl palmitate as a dietary vitamin C source for rainbow trout (Salmo gairdneri)

The vitamin C activity of ascorbyl palmitate was investigated for use in salmonid diets. Three groups of “swim up” rainbow trout (Salmo gairdneri) fry were fed identical basal diets for 12 weeks supplemented with no form of ascorbic acid (group A), 600 mg ascorbic acid/kg (group B) and ascorbyl palmitate in equimolar amounts to the group B supplement (group C). The fish in group C showed reduced growth for the first 8 weeks. From week 8 onwards growth rate in group C paralleled that in group B, while the fish fed the diet devoid of any form of vitamin C (group A) showed a reduced growth rate. The concentrations of ascorbic acid at the end of the experiment were < 0.5, 64 and 55 μg/g in whole fish and < 0.5, 156 and 118 μg/g in the liver for groups A, B and C, respectively. Vertebral collagen in fish fed ascorbyl palmitate contained similar levels of hydroxyproline to that in fish fed ascorbic acid as vitamin source. An in vitro assay demonstrated the presence in the rainbow trout gut of enzymatic activity hydrolyzing the ascorbyl palmitate.

Contents and organ distribution of vitamin B6 in Atlantic salmon (Salmo solar) and turbot (Psetta maxima) during the reproductive cycle

Abstract Vitamin B6 in the muscle of Atlantic salmon (Salmo salar) and turbot (Psetta maxima) showed significant negative correlation with GSI, while it was positively correlated in the ovaries, in concentration as well as in total contents of organs. It is suggested that vitamin B6 in muscle constitutes the main body stores, and is transferred to the ovaries of Atlantic salmon during the last stages of gonadal build up when the fish does not feed. In the continuously fed turbot, it is likely that gonadal vitamin B6 originated from the diet as well. Vitamin B6 concentration in Atlantic salmon egg yolk was 60% higher than in the larvae body at hatching. Later, vitamin B6 was taken up by the fry at the onset of feeding concomitant with the disappearance of the yolk.

Effects of dietary lipid, vitamins and minerals on total amounts and redox status of glutathione and ubiquinone in tissues of Atlantic salmon (Salmo salar): a multivariate approach.

The hypothesis of the present study was that Atlantic salmon (Salmo salar) would respond to large variations in supplementation of dietary pro- and antioxidants, and marine lipid, with adjustment of the endogenously synthesised antioxidants, glutathione (GSH) and ubiquinone (UQ). An experiment with 2(7-3) reduced factorial design (the number of cases reduced systematically from 2(7) (full design) to 2(4) (reduced design)) was conducted, where vitamins, minerals and lipid were supplemented in the diet at high and low levels. For the vitamins and minerals the high levels were chosen to be just below anticipated toxic levels and the low levels were just above the requirement (vitamin C, 30 and 1000 mg/kg; vitamin E, 70 and 430 mg/kg; Fe, 70 and 1200 mg/kg; Cu, 8 and 110 mg/kg; Mn, 12 and 200 mg/kg). For astaxanthin, the dietary levels were 10 and 50 mg/kg and for lipid, 150 and 330 g/kg. The experiment was started with post-smolts (148 (sd 17 g)) and lasted for 5 months. The only effect on GSH was a minor increase ( < 10 %) in total concentration in the liver in response to high dietary lipid. GSH redox state was not affected. UQ responded to dietary lipid, astaxanthin and vitamin E, both with regard to total concentration and redox state. Except for an effect of Fe on plasma GSH, the trace elements and vitamin C had no effect on tissue levels and oxidation state of GSH and UQ. This shows that the endogenous redox state is quite robust with regard to variation of dietary pro- and antioxidants in Atlantic salmon.

Changes in protein abundance in the vertebral columnof Atlantic salmon (Salmosalar) fed variable dietary P levels

Previously we have applied a comparative 2DE-approach to investigate the proteome of Atlantic salmon (Salmo salar) with vertebral deformities (Pedersen et al., 2011). This work lead to the identification of a new interesting candidate for the process that leads to fused vertebrae; matrilin-1. This finding was further confirmed by real-time PCR analysis and immunohistochemistry, and illustrates the strength of applying a non-hypothetical approach towards identifying new markers for bone development.