Evaluating dietary supply of microminerals as a premix in a complete plant ingredient-based diet to juvenile rainbow trout (Oncorhynchus mykiss)

Two basal diets M0 and V0 were formulated with marine and plant based ingredient composition. Seven experimental diets were prepared from the two basal diets namely M0, M100, V0, V30, V60, V100 and V150 by incorporating different levels of a micromineral premix (Cu, Fe, Mn, Se and Zn). Triplicate groups of rainbow trout (initial weight: 20 g) reared at 17°C were fed one of each diet to apparent visual satiation over 12 weeks. Among the V diet fed fish, growth and feed intake exhibited maximal response at V60 level of premix inclusion; Apparent availability coefficient of Fe, Cu and Zn decreased linearly with increasing level of premix whereas apparent availability coefficient of Mn and Se was unaffected. The available dietary concentration in basal V0 diet was for Fe, 20.6; Cu, 2.8; Mn, 6.5; Zn, 17.3 and Se, 0.195 (in mg/kg DM) and in the M0 diet for Fe, 63.3; Cu, 5.2; Mn, 2.9; Zn, 35.2 and Se, 0.87 (in mg/kg DM). In reference to NRC (Nutrient requirements of fish and shrimp. Washington, DC: National Research Council, The National Academies Press, 2011) recommendations, the V0 basal diet accounted for 34.3%, 92.9%, 53.9%, 115% and 130.2% and the contribution from M0 diet for 105.5%, 173.3%, 24.2%, 234.7% and 580% of the minimal dietary inclusion levels of Fe, Cu, Mn, Zn and Se to rainbow trout, respectively. However, data on whole body mineral contents showed that normal levels were maintained only for Cu and Mn through supply from basal V0 diet. For Zn and Se, available supply even from the highest supplemented diet (V150) was not sufficient to maintain normal body mineral levels of rainbow trout in the present study. On the whole, optimal dietary inclusion levels of microminerals are altered while using fishmeal-free diets for rainbow trout

Antioxidant defense system is altered by dietary oxidized lipid in first-feeding rainbow trout (Oncorhynchus mykiss)

International audienceHigh concentrations of n − 3 polyunsaturated fatty acids (PUFA) that are readily susceptible to lipid peroxidative damage are found in fish feeds and in the tissues of fish, especially in early developmental stages. A dietary phospholipid (PL) supply has been shown to be beneficial during these critical stages. The objective of the study was to characterize the response of the antioxidant defense system under dietary prooxidant conditions in presence or absence of dietary PL during early development of rainbow trout. Rainbow trout (Oncorhynchus mykiss) at the first-feeding fry stage (mean weight: 66 ± 2 mg) or at the fingerling stage (mean weight: 1.5 ± 0.4 g) were fed 4 semi-purified diets supplemented with 12% fresh fish oil or 12% oxidized fish oil and 6% soybean lecithin or 6% soybean oil for 4 weeks at 17 °C. At fry stages, rainbow trout fry fed the PL-supplemented diets had a significantly higher final body weight than fry fed the PL-free diets (0.37 ± 0.07 vs. 0.27 ± 0.03 g, respectively). Dietary inclusion of oxidized lipid reduced growth (0.19 ± 0.02 vs. 0.45 ± 0.07 and 2.5 ± 0.6 vs. 4.8 ± 0.6 g, respectively) and increased the mRNA expression of antioxidant enzymes such as glutathione reductase and glutathione S-transferase at both developmental stages. However, dietary control of antioxidant enzyme activities and vitamins was low in rainbow trout fry whereas increased activities of antioxidant enzymes and decreased tocopherol contents were noticed in rainbow trout fingerlings fed oxidized lipid compared to rainbow trout fry fed fresh oil. This resulted in higher content of lipid peroxidation products in rainbow trout fry fed oxidized lipid compared to fish fed fresh lipid whereas this difference was reduced at the fingerling stage. The present study demonstrates that rainbow trout fry are more susceptible to oxidative stress induced by dietary oxidized lipid than rainbow trout fingerlings, possibly due to delayed response or lack of complete development of endogenous antioxidant defense syste

Effects of dietary vitamin E supplementation and fish oil replacement on growth performance and lipid peroxidation in rainbow trout (Oncorhynchus mykiss)

Résumé posterInternational audienc

Conséquences d'un déséquilibre alimentaire en méthionine sur la croissance et le métabolisme de la truite

Session NutritionNational audienc

Effects of dietary vitamin E supplementation and fish oil replacement on antioxidant and fatty acid status in rainbow trout (Oncorhynchus mykiss) juveniles

International audienc

Comparison of endogenous loss and maintenance need for minerals in rainbow trout (Oncorhynchus mykiss) fed fishmeal or plant ingredient-based diets

Mineral needs as affected by changes in dietary protein and oil sources were studied in rainbow trout. Duplicate groups (n = 30 fish per replicate) of rainbow trout (initial BW: 37 g) were fed either a fish meal/fish oil-based (M) or a complete plant ingredient (V)-based diet at four graded ration (R) levels [apparent satiation (AS), R75, R50 and R25 % of AS]; one treatment group was maintained under starvation. The feeding trial lasted 12 weeks at a water temperature of 17 °C. Dietary intake, apparent digestibility and initial and final whole-body composition data were used to calculate mineral gain which was regressed against digestible mineral intake (both expressed as mg or µg kg-0.8 day-1). Starvation loss (SL), endogenous loss of fed fish (ELF, y-intercept at x = 0) and point of intake for zero balance (PZB, x-intercept at y = 0) were used as estimates of maintenance requirements. SL provided the lowest estimate, ELF provided the net requirement of a mineral for maintenance and PZB provided the digestible dietary intake required to meet maintenance (SL <ELF <PZB). Dietary ingredient composition did not significantly affect the digestible mineral supply required for maintenance (PZB) for any of the minerals (P, Mg, K, Cu and Zn) studied. However, ELF of micro-minerals such as Cu and Zn were significantly affected. The ELF of Cu was significantly lower and that of Zn was significantly higher in V group compared with M-fed fish. Further studies on the effects of such changes in dietary formulations on micro-mineral metabolism are warranted

Post-prandial changes in plasma mineral levels in rainbow trout fed a complete plant ingredient based diet and the effect of supplemental di-calcium phosphate

Post-prandial changes in plasma mineral levels and utilisation of minerals in rainbow trout fed complete plant ingredient based diets with or without supplemental di-calcium phosphate (DCP) were studied over an 8 week period. Three diets were used: diet M was FM and fish oil (FO) based diet (control); diets VP0 and VP + (V diets) were completely based on plant derived protein and lipid sources. One of the V diets (VP +) was supplemented with DCP to supply 5 g kg- 1 dry matter available phosphorus (P); while the other diet (VP0) was not supplemented with DCP. Change in dietary protein source significantly affected the post-prandial pattern in plasma levels of P (p 0.05). Based on measurement of apparent digestibility, growth and whole body composition analyses, mineral balances were established showing that supplementation of DCP led to significant increase in whole body P concentration and P retention in VP +, comparable to fish fed diet M with significantly (p <0.05) reduced faecal and non-faecal P losses. There was improved post-absorptive retention (as % of available intake) of Ca (p <0.05), Mg (p <0.05) and K (p <0.05) in VP + compared to VP0. Utilisation of Cu (p <0.05) and Zn (p <0.01) was negatively affected. DCP supplementation to complete plant ingredient based diet increased the post-prandial plasma levels, whole body concentration and utilisation of macro-minerals (P, Ca, Mg and K) whereas that of micro-minerals especially Zn and Cu were negatively affected

Impact of broodstock nutrition on the quality of tissue lipids and reproductive performance in European eel (Anguilla anguilla)

Résumé posterInternational audienc

Effects of dietary sulphur amino acid deficiency on growth, muscle cellularity and molecular markers in brain and liver of rainbow trout

International audienc