Growth, feeding and thyroxine‐related responses of hybrid striped (sunshine) bass ( Morone chrysops ♀ X M. saxatilis ♂) fed de‐oiled carinata ( Brassica carinata ) meal

Abstract

De‐oiled (<10 g/kg oil) carinata (Brassica carinata) meal is high (>400 g/kg) in protein, but its use in fish diets will likely be limited mainly by glucosinolates (GLS), sinapine and crude fibre. Two feeding experiments were conducted to determine the response of hybrid striped bass (Morone chrysops ♀ X M. saxatilis ♂, HSB) to inclusion of cold‐pressed carinata meal (CPCM) in diets. Cook extrusion reduced an average of 44% and 57% of GLS and sinapine concentrations in diets, respectively. In experiment 1, diets containing 0.71–2.71 μmoles of GLS and 0.034–0.181 mg of sinapine/g did not significantly (p > .05) reduce feed consumption, utilization or growth, resulting in similar concentrations of thyroxines and consequently no effect on deiodinase enzymes. In experiment 2, there was a significantly reduced (p < .05) feed consumption in fish fed diets containing 5.58–9.52 μmoles of GLS and 0.54–0.75 mg of sinapine/g, resulting in HSB exhibiting lethargic swimming and feeding behaviours, and consequently poor feed utilization and growth. Cook extrusion reduced about half of GLS and sinapine, and HSB tolerated ≤2.71 μmoles of GLS and ≤0.31 mg of sinapine/g of diet without affecting feed consumption and utilization, growth and thyroid metabolism.

Effect of fish meal replacement with CarinataBrassica carinatain low animal protein diets of rainbow troutOncorhynchus mykiss(Walbaum) on trypsin activity, protein and amino acid digestibility and bioavailability

“…De‐oiled (<10 g/kg oil) CM with hulls containing 480 g/kg crude protein was 92.4% digestible and had similar leucine but more arginine, histidine, methionine, threonine, tryptophan and cysteine content than solvent‐extracted (SE) soybean meal with hulls (NRC, ). However, because of the negative effect of glucosinolates (GLS) and their breakdown products on long‐term diet palatability (Kasiga, Fey, Berhow, Bruce, & Brown, ), the use of de‐oiled CM in fish diets was not feasible without further processing. Subjecting de‐oiled CM to aerobic conversion (AC) to reduce GLS (by 84%) in the processed meal (ACCM) also increased crude protein from 480 to 570 g kg −1 , and all EAA concentrations were improved, except for tryptophan.…”

Rapeseed proteins as fishmeal alternatives: A review

“…As mentioned in a previous chapter, breakdown of glucosinolates is dependent on a multitude of factors including activity of the enzyme myrosinase, parent glucosinolates, environmental pH, presence of ferrous ions and others 229,236–240 . The breakdown products include isothiocyanates, thiocyanates, nitriles, oxazlidinethiones, goitrin and vinyloxa‐zolidinethiones 39,199,273 . The exact effects from these products on health of fish are, like effects on feed intake, dependent on which breakdown product is present and at which concentration 199 .…”

“…Glucosinolates and their brake down products can putatively limit diet palatability 26,49,232 . Isothiocyanates, progoitrin and sinigrin for example, have been associated with bitter taste 226,232–234 although bitterness of different glucosinolate components can differ 199 . The brake down products in particular are considered to cause deleterious effects in fish 45,235 .…”

“…Nonetheless, results from previous studies demonstrated that lesser amounts of glucosinolates should be ineffective in impairing feed intake significantly in most species of fish, at least if myrosinase has been deactivated. The composition of different glucosinolates and consequently their breakdown products might also be of importance, as their bitterness can vary 199 …”

“…Glucosinolates and their breakdown products have been associated with different negative effects on animal health 45,232 . These effects included liver haemorrhage, toxicity for liver and kidney, increased organ weight, disturbed thyroid function like goitre, neurotoxicity, mutagenicity and even mortality in animals, including fish 42,45,101,122,135,158,199,226,273,293 . In general, breakdown products of glucosinolates are considered more detrimental to fish health in comparison with the biologically inactive glucosinolates 42,242,273 .…”