Optimization of Dietary Manganese for Rainbow Trout, Oncorhynchus mykiss, Fed a Plant‐based Diet

Abstract

Juvenile rainbow trout were fed a plant-based diet supplemented with inorganic Mn added at 0, 0.5, 1, 2, 4, 8, 16, or 32 mg/kg diet for 12 wk. Whole-body Mn concentrations increased with increasing dietary levels. Rainbow trout fed 2-8 mg Mn/kg diet exhibited weight gain that was significantly higher than fish fed 0, 0.5, 1, 16, and 32 mg Mn/kg diet. Feed conversion ratio (FCR) showed a similar trend, where FCR values decreased with increasing dietary Mn until concentrations reached 8 mg Mn/kg, after which they increased. A rational nonlinear model (R 2 = 0.84) fit to weight-gain data showed that the optimal predicted supplementation level for Mn was 4.8 mg/kg diet. The optimal predicted supplementation level for Mn was similar for FCR (5 mg Mn/kg diet). The predicted 5 mg/kg diet of supplemental Mn required for the plant-based diet formulation examined in this study is lower than the National Research Council-recommended supplementation level of 12 mg/kg. However, due to potential differences in bioavailability or retention of Mn among plant-protein sources, the level of dietary supplementation for optimal growth could be slightly higher or lower depending on the dietary formulation.

Recommendations for dietary level of micro-minerals and vitamin D3 to Atlantic salmon (Salmo salar) parr and post-smolt when fed low fish meal diets

“…Therefore, whole-body concentration or retention, a relatively well-accepted approach to determine mineral requirement was also used (Shearer & Asgard, 1990; Shearer, 1995). Reduction in whole-body retention of Cu, Mn and Zn at higher NP (200 and 400%) levels confirmed the response of AAC, indicating that the requirement for Cu, Mn and Zn had been met with 100–150% NP levels for Atlantic salmon parr in freshwater, which are in agreement with recent reports in rainbow trout fed low fish meal diets (Read et al, 2014; Welker et al, 2016; Antony Jesu Prabhu et al., 2018a; Welker et al, 2018). Iodine requirement was met only at NP inclusion of 150–200%, indicating a requirement of 0.83 ± 0.16 mg iodine per kg diet for Atlantic salmon parr in freshwater, which is slightly lower but in close agreement (1-1.1 mg/kg diet) with the requirement reported in other salmonids, such as rainbow trout and Pacific salmon, Oncorhynchus spp (NRC, 2011).…”

“…Moreover, plant ingredients are known to contain one or more anti-nutritional factors, which further limits the availability of inherent and supplemented micro-nutrients. Recent reports show that the available levels required for Zn, Mn and Se in complete plant-based diets for rainbow trout to be higher than recommended by NRC (2011) (Welker et al, 2016; Antony Jesu Prabhu et al., 2018a; Welker et al, 2018). Life stage and environment are other factors that might also alter dietary nutrient requirements in fish, especially of minerals which can also be absorbed from the water (Bury, Walker & Glover, 2003).…”

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“…The search for sustainable sources of protein to replace the fish meal, has been a priority for the aquaculture industry in the last years (Gatlin et al, 2007). Plant protein sources has been recognized for many years as viable ingredients to be included in feeds for salmonids (Welker et al, 2018). We report the use of soy, rice and corn protein concentrates added with the prebiotics (FOS and MOS) for rainbow trout fingerlings.…”

“…In many countries the feeds for the rainbow trout (Oncorhynchus mykiss Walbaum, 1792) still rely on fishmeal (FM), a product derived from the marine fisheries (Tacon & Metian, 2008;Cid et al, 2020) and with the actual production fully utilized, the search of replacements for FM has been a top priority for the aquacultural industry (Gatlin et al, 2007). Plant origin products, such meals and oils of cereals, legumes, and oily seeds are economical alternatives to fish-origin products (Welker et al, 2018) and the protein concentrates are the most promissory ingredients to be included in salmonid feeds (Hardy, 2010). The plant protein concentrates such as those obtained from soy, rice, and corn, can be used to replace 75% of fishmeal in the diet of salmonids (Refstie et al, 2001).…”

Inclusion of fructooligosaccharides and mannanoligosaccharides in plant-protein based diets for rainbow trout (Oncorhynchus mykiss) fingerlings and its effects on the growth and blood serum biochemistry

“…In many countries the feeds for the rainbow trout (Oncorhynchus mykiss Walbaum, 1792) still rely on fishmeal (FM), a product derived from the marine fisheries (Tacon & Metian, 2008;Cid et al, 2020) and with the actual production fully utilized, the search of replacements for FM has been a top priority for the aquacultural industry (Gatlin et al, 2007). Plant origin products, such meals and oils of cereals, legumes, and oily seeds are economical alternatives to fish-origin products (Welker et al, 2018) and the protein concentrates are the most promissory ingredients to be included in salmonid feeds (Hardy, 2010). The plant protein concentrates such as those obtained from soy, rice, and corn, can be used to replace 75% of fishmeal in the diet of salmonids (Refstie et al, 2001).…”