Comparative effects of dietary l-carnitine supplementation on diploid and triploid rainbow trout (Oncorhynchus mykiss)

Abstract

This study compared the effects of dietary l‐carnitine and ploidy on growth performances and fatty acid content in rainbow trout (Oncorhynchus mykiss). Fish [initial body weight (BW) = 30 g] reared under high density (50 kg biomass m−3) were hand‐fed in triplicate (3 tanks treatment−1, 34 fish tank−1) twice a day, with three nutritionally identical diets containing 15, 200 or 530 mg l‐carnitine kg−1 of diet. No significant growth differences were observed over a 56‐day grow‐out period, during which BWs increased threefold. Growth performances and survival were not significantly affected by either ploidy or dietary l‐carnitine content, although daily growth index showed an increasing trend (2.52–2.65% day−1) with increasing dietary l‐carnitine. Body l‐carnitine content increased significantly with dietary l‐carnitine content. Diploid fish had higher plasma ammonia (716–725 μmol L−1) and osmolality (297–303 mOsm) levels than triploid trout (523–649 μmol L−1 and 285–291 mOsm, respectively). l‐carnitine, ploidy and their interaction showed to affect significantly the concentration of several fatty acids. Palmitoleic (16:1), oleic (18:1) and erucic (22:1) acids showed lower concentrations, while the eicosadienoic (20:2n‐6) and arachidonic (20:4n‐6) acids were elevated in liver of triploid fish. Eicosapentaenoic acid (22:5n‐3) was significantly higher in fish fed 200 mg than in fish fed 15 mg l‐carnitine.

Triploidy does not decrease contents of eicosapentaenoic and docosahexaenoic acids in filets of pink salmon Oncorhynchus gorbuscha

“…Moreover, higher percentage of EPA and DHA in mature diploids compared to that of triploids, found by other authors (Flajshans et al, 2010;Ozorio et al, 2012;Manor et al, 2012Manor et al, , 2014Ribeiro et al, 2012), was confirmed in our study. It should be emphasized, that immature diploid fish did not differ significantly from triploids concerning EPA and DHA percentage.…”

“…It is important to note, that All the above data on less PUFA in triploids were based on measurements of their percentages in total fatty acids (Flajshans et al, 2010;Ozorio et al, 2012;64 65 Manor et al, 201264 65 Manor et al, , 2014Ribeiro et al, 2012). Meanwhile, it was demonstrated, that to for estimation of nutritive value for humans, measurements of PUFA per mass of consumed filets, rather than their percentage in total fatty acids should be carried out (Gladyshev, Sushchik, Gubanenko, Demirchieva, & Kalachova, 2007;Gladyshev et al, 2012;Huynh& Kitts, 2009).…”

“…Oncorhynchus mykiss are often used and their fatty acid composition is studied (Ozorio et al, 2012;Manor et al, 2012Manor et al, , 2014Ribeiro et al, 2012). Studies of other salmonid species are also desirable to expand and clarify data on nutritive quality of triploid fish.…”

“…Due to are sterile and at adult stages exhibit better growth than their diploid counterparts, because the 53 sterility prevents energy loss for gamete production and negative effects of sexual maturation for 54 meat quality (Flajshans et al, 2010;Ozorio et al, 2012).Moreover, the use of sterile triploids in aquaculture can reduce the risks of propagation of non-native escapees into the wild (Ozorio et al, 2012;Ribeiro, Gomes, Vieira, Tabata, Takahashi, & Moreira, 2012). Nevertheless, in spite of the better fillet quality of triploids because of the prevention of mobilization of stored lipids for gonad development, they were reported to have a lesser sum of PUFA in the flesh compared to diploid individuals (Flajshans et al, 2010;Ozorio et al, 2012;Manor, Weber, Salem, Yao, Aussanasuwannakul, & Kenney, 2012;Ribeiro et al, 2012;Manor, Weber, Cleveland, & Kenney, 2014). Therefore, it was suggested to improve PUFA content in muscle of triploids by dietary supplementation of PUFA (Ribeiro et al, 2012).…”

The effect of dietary energy level on growth and nutrient utilization by juvenile diploid and triploid brook charr,Salvelinus fontinalis

“…) and fatty acid metabolism (Ozório et al . ; Manor et al . ), suggesting differences in lipid utilization between diploids and triploids that precede, but continue through, energy investment into gonadal development.…”