The Effect of Culture System on Proximate Composition and Amino and Fatty Acid Profiles of Peled Coregonus peled Fillets

Defatted black soldier fly (Hermetia illucens) in pikeperch (Sander lucioperca) diets: Effects on growth performance, nutrient digestibility, fillet quality, economic and environmental sustainability

The use of insect meal in aquafeed formulations has recently gained attention. Detailed knowledge about the inclusion levels for pikeperch (Sander lucioperca), a promising candidate for intensive aquaculture in Europe remains, however, fragmented. In the present study, 4 isoproteic (45% dry matter) and isoenergetic (21 MJ/kg) diets were formulated, including a control diet (H0) containing 30% fishmeal (FM) on an as-fed basis and the other 3 diets in which FM protein was replaced by defatted black soldier fly (Hemetia illucens) meal (HIM) at 25%, 50%, and 100% (diet abbreviation H9, H18 and H36, corresponding to an inclusion level of 9%, 18% and 36%, respectively). The feeding trial was performed in triplicate groups of 50 juvenile pikeperch (mean weight, 68.7 g) fed with experimental diets for 84 d during which the growth performance, nutrient digestibility, fillet quality and economic and environmental sustainability of rearing pikeperch were evaluated. Our findings indicated that pikeperch in H0, H9, and H18 groups displayed better results regarding growth performance indices, except for survival rate where no significant difference among groups was recorded (P = 0.642). A significantly lower organ-somatic index, including hepatosomatic, viscerosomatic and perivisceral fat index, was found in fish in H18 groups than other groups (P < 0.05). Inclusion of HIM affected the digestibility of the nutrients and resulted in an almost linear reduction in the apparent digestibility coefficient of dry matter and protein. Concerning the fillet quality, dietary HIM negatively affected the protein and ash contents of the fish fillets, while the crude fat remained unchanged. Dietary HIM did not significantly modify total saturated, monounsaturated and polyunsaturated fatty acids in the fillets of fed pikeperch (P > 0.05) but did reduce total n-3 fatty acids (P = 0.001) and increased total n-6 (P < 0.001). Increasing inclusion levels of HIM reduced the environmental impacts associated with fish in-to-fish out ratio but entailed heavy burdens on energy use and eutrophication. Low and moderate inclusion levels of HIM did not negatively affect land use and water use compared to an HIM-free diet (P > 0.05). The addition of HIM at a level as low as 9% elicited a similar carbon footprint to that of the control diet. The economic conversion ratio and economic profit index were negatively affected at increased insect meal inclusion levels. This study has shown that the incorporation of HIM in feed formulations for pikeperch is feasible at inclusion levels of 18% without adverse effects on growth performance parameters. The feasibility also highlighted the environmental benefits associated with land use and marine resources required to produce farmed fish.

Effect of feed composition on the nutritional value of meat of African catfish

The article outlines the results of the research into the influence of feed composition on the amino acid value of African catfish meat. It has been shown that quality characteristics of fish meat depend on protein and fat content. It has been proved that high-protein feed ensures increase in the content of all amino acids in African catfish meat. Nevertheless, protein and fat content in the muscles of the studied fish is more than 2 times higher than the same indicator in the fish on low-protein and low-fat diet. Meat of the African catfish is rich in two amino acids – leucine and lysine. Two amino acids, tryptophan and methionine, are limitative at a high protein diet. At a lower protein diet, isoleucine amino acid is also added. The amino acid composition of African catfish meat is highest at high-protein feeds. The amino acid index of African catfish muscles at high-protein feeds is 0.48, significantly exceeding the index of fish bred on feeds with a reduced protein content. The conducted studies have shown that the use of high-protein feeds in catfish breeding stimulates protein metabolism, enriching the amino acid composition of muscle tissue and increasing the nutritional value of fish as a food product. The research has been funded by the Russian Foundation for Fundamental Research, project No. 18-016-00127.