Essential amino acids
With respect to proteins, plant raw materials do not
provide the same quantity of essential amino acids (EAA) as fish meal, and this
replacement must be accompanied by supplementation of the diet in synthetic EAA.
Studies in the gilthead sea bream assessed the long-term effects on growth and flesh quality of a high rate of replacement of fish meal by plant proteins. Bream with a mean initial body weight of 100 g were fed for a year with two feeds.
The Fish Meal (FM) feed contained only fish meal, while the Plant Protein (PP) meal (supplemented in EAA) contained 75% of a mixture of plant proteins (maize and wheat gluten, extruded pea, extruded rapeseed and wheat cake) instead of fish meal. Growth performances were similar with the two feeds.
Feed intake was higher with the FM feed, while dietary efficiency and the protein efficiency coefficient were better with the PP feed. Fillets from sea bream fed with the mixture of vegetable oils contained higher levels of lipids, a lower proportion of omega-3 fatty acids and higher levels of omega-6 fatty acids. The amino acid composition of fillets differed little as a function of diet. Sensorial analyses on cooked fillets did not enable any discrimination between the two groups.
A 75% replacement of fish meal by plant proteins, accompanied by adequate supplementation with EAA, is thus possible in the long term in the gilthead sea bream without there being any negative effects on growth performance and the sensory quality of flesh. Research is now aiming to assess the possibilities of the combined replacement of fish meal and oils in feeds for aquaculture.
Salmon can grow on low taurine feeds
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