The effect of dietary vitamin A on the immunocompetence of Atlantic salmon (Salmo salar L.)

Abstract

Atlantic salmon, Salmo salar L. were maintained on diets containing low (0.37 mg kg(-1) diet), normal (1.95 mg kg(-1) diet) and high (15 mg kg(-1) diet) levels of vitamin A fed at 1.5% body weight per day. After 4 months, liver vitamin A levels reflected dietary intake and growth rates of all three groups were similar. Kidney leucocyte migration and serum bactericidal activity were found to be significantly reduced in fish fed low levels of vitamin A. On the other hand, high levels of vitamin A in the diet were found to augment serum antiprotease activity relative to the levels found in the other dietary groups. However, phagocyte respiratory burst activity, bactericidal activity and eicosanoid production were unaffected by the dietary vitamin A regime, as were lymphocyte functions (lymphokine and antibody production) and both serum lysozyme and classical complement activity. That the overall immunomodulatory effect of vitamin A was small was reflected in the resistance to Aeromonas salmonicida. No significant differences were found between the different vitamin A intake groups despite a trend to decreased resistance in the low vitamin A diet group.

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“…And based on the SGR data, the supplementation dose in this study should be no less than 4769 IU/kg, which is similar to the requirement values reported for hybrid tilapia (Hu et al 2006), and greasy grouper (Mohamed et al 2003), which have requirements between 2000 and 5000 IU/kg. In our study, different VA levels showed no significant effect on the FCR and FR, as reported in Atlantic salmon by Thompson et al (1994). This indicated that VA may not improve the palatability of the feed to promote growth.…”

Cytokines in fish: an update

“…Despite the fact that Zn 2+ can activate carp lymphocytes to undergo proliferation, no e#ect on cytokine release was found. Similarly, no e#ect of dietary intake of vitamin C (Hardie et al, 1991) or vitamin A (Thompson et al, 1994) was found on MAF release by Atlantic salmon head kidney leucocytes, although addition of vitamin C to leucocytes from vitamin C depleted rainbow trout did augment MAF production (Hardie et al, 1993). An aqueous extract of liquorice, glycyrrhizin, has also been shown to augment MAF release from mitogen stimulated trout leucocytes (Jang et al, 1995c), possibly through its known ability to promote IFN release since IFN-is a potent MAF.…”

Effects of dietary protein source on growth, immune function, blood chemistry and disease resistance of Atlantic salmon (Salmo salarL.) parr

“…g , 5 min) to reveal plasma. Plasma was used for measurement of lysozyme activity by determining the rate of lysis of a Micrococcus lysodeikticus suspension and using hen egg white lysozyme (Sigma Chemical Co., Castle Hill, NSW, Australia) as standard as described by Thompson et al (1994). The volume of plasma required to inhibit 50% of a standard trypsin activity was used to quantify antiprotease activity (Ellis, 1990).…”