Establishing an upper level of intake for vitamin A in Atlantic salmon (Salmo salarL.) postsmolts

Abstract

The vitamin A (VA) concentration in salmon aquaculture feeds is varying and may lead to sublethal adverse effects. In this study, 135 g Atlantic salmon postsmolts were given eight diets in duplicates with 6, 12, 26, 55, 82, 112, 360 and 749 mg retinol (ROL) kg À1 for 116 days. Subsequently, fish given 6, 82 and 749 mg ROL kg À1 were transferred to a common net pen and given a standard commercial diet for further 28 weeks. Feed conversion rate, liver functionality and markers of VA homoeostasis were not negatively affected by dietary VA level, but chronic high VA intakes led to adverse effects on growth and bone health. In plasma, there was an antagonistic effect of dietary ROL on circulating 1,25 (OH) 2 vitamin D 3 (calcitriol). Moreover, a dose-response of VA on craniofacial deformities, condition factor and vertebral morphometry and mechanical strength was observed. Vertebral deformities were observed after 28 weeks on a standard diet and not immediately after the 116 days on the experimental diet. Elevated VA is a risk factor for bone deformities, and the dietary intake of VA should not exceed 37 mg ROL kg À1 body weight day À1 in Atlantic salmon postsmolts.

The prevalence of vertebral deformities is increased with higher egg incubation temperatures and triploidy in Atlantic salmon Salmo salar L.

“…A number of factors are known to increase the risk of jaw deformities in production fish including suboptimal temperatures (Bolla & Holmefjord 1988), nutritional deficiencies (Vitamin A, Ørnsrud et al 2013), and light source and tank colour (Bolla & Holmefjord 1988;Cobcroft & Battaglene 2009). In the current study, it is unknown whether the observed jaw deformities were caused by physiological differences or mechanical damage through differences in behaviour (Morrison & Macdonald 1995) or ventilation rates (Roberts, Hardy & Sugiura 2001;Ørnsrud et al 2013). It is possible that triploids were suffering from phosphorus deficiency (see above), but it is also interesting to note that triploid salmon are suggested to have lower temperature optima than diploids with higher metabolic rates at similar temperatures to those used in the current study (i.e.…”

“…In the current study, it is unknown whether the observed jaw deformities were caused by physiological differences or mechanical damage through differences in behaviour (Morrison & Macdonald ) or ventilation rates (Roberts, Hardy & Sugiura ; Ørnsrud et al . ). It is possible that triploids were suffering from phosphorus deficiency (see above), but it is also interesting to note that triploid salmon are suggested to have lower temperature optima than diploids with higher metabolic rates at similar temperatures to those used in the current study (i.e.…”

“…A number of factors are known to increase the risk of jaw deformities in production fish including suboptimal temperatures (Bolla & Holmefjord ), nutritional deficiencies (Vitamin A, Ørnsrud et al . ), and light source and tank colour (Bolla & Holmefjord ; Cobcroft & Battaglene ). In the current study, it is unknown whether the observed jaw deformities were caused by physiological differences or mechanical damage through differences in behaviour (Morrison & Macdonald ) or ventilation rates (Roberts, Hardy & Sugiura ; Ørnsrud et al .…”

Current knowledge on biotin nutrition in fish and research perspectives

“…Hypervitaminosis has been reported for fat-soluble vitamins such as vitamins A and D (Hilton 1983). High dietary intakes of vitamin A may cause toxic effects in certain fish (Atlantic salmon, Japanese flounder, Paralichthys olivaceus, tilapia, Oreochromis niloticus) and the main toxic effects are associated with bone malformation (Dedi et al 1995(Dedi et al , 1997Ørnsrud et al 2002, 2013Saleh et al 1995). The sensitivity to hypervitaminosis A appears to be species specific and life stage dependent in fish, which has also been shown for mammals (Nau et al 1994).…”

“…The sensitivity to hypervitaminosis A appears to be species specific and life stage dependent in fish, which has also been shown for mammals (Nau et al 1994). This difference in toxicity between water-and fat-soluble vitamins is due to the fact that excess water-soluble vitamin is excreted by the fish, while excess fat-soluble vitamin is accumulated in the lipid fraction of the fish body (Olivia-Teles 2012; Ørnsrud et al 2002, 2013Halver 2002). Since biotin is not retained in the body, the maximum tolerable limit or toxicity of this vitamin may not be a concern for fish and other animals (NRC 1987).…”