• Microalgal-based aquaculture feeds promise sustainability of agricultural sector. • Carotenoids-laced aquatic meal enhances acceptability of aquaculture products. • High-quality microalgal products offer nutritional and positive health benefits. • Microalgal protein promotes growth and boosts immune system of aquatic life. • Polyunsaturated fatty acids of algae origin contain both omega-3 and omega-6.

Gut microbiota impacts fish metabolism, nutrient utilization, and health. We know little about how temperature and diet interact with rainbow trout gut microbes. A total of 288 fish (average body weight: 45.6 g) fed four iso‐caloric, ‐lipidic, and ‐nitrogenous diets comprised crude protein (40%) and lipid (20%) manufactured as 100% animal‐based protein (AP) and blend of 50 fish oil (FO)/50 camelina oil (CO), 100% AP and 100% CO, 100% plant‐based protein (PP) and blend of 50 FO/50 CO or 100% PP and 100% CO at 14 or 18°C water temperature. Gut content was analyzed using 16S rRNA gene and shotgun sequencing. Alpha‐diversity did not change significantly. Regardless of diet, Tenericutes, Firmicutes, Proteobacteria, Spirochaetes, Bacteroidetes, and Actinobacteria dominated. At family level, Aeromonadaceae and Enterobacteriaceae dominated at 18°C, while Mycoplasmataceae dominated at 14°C. Moreover, genes relating to amino acid, carbohydrate, fat, and energy metabolisms and fatty acid biosynthesis significantly increased at 18°C. Functional profiles did not vary significantly among diets, except for a higher methionine and cysteine metabolism in fish fed plant ingredient compared animal diet, suggesting trout fed plant‐derived protein mixed with CO could be as effective as those fed fish meals mixed with 50/50 FO and CO.

Impacts of plant-based ingredients and temperatures on energy metabolism in rainbow trout was investigated. A total of 288 fish (mean body weight: 45.6g) were fed four isocaloric, isolipidic and isonitrogenous diets containing 40% protein and 20% lipid and formulated as 100 % animal-based protein (AP) and a blend of 50% fish oil (FO) & 50 % camelina oil (CO); 100 % AP and100 % CO; 100 % plant-based protein (PP) and a blend of 50% FO & 50 % CO or 100 % PP and 100 % CO at 14 or 18 °C for 150 days. Diet did not significantly affect weight gain (WG) (P=0.1902), condition factor (CF) (P=0.0833) or specific growth rate (SGR) (P=0.1511), but diet significantly impacted both feed efficiency (FE) (P=0.0076) and feed intake (FI) (P=0.0076). Temperature did not significantly affect WG (P=0.1231), FE (P=0.0634), FI (P= 0.0879), CF (P=0.8277) or SGR (P=0.1232). The diet x temperature interaction did not significantly affect WG (P=0.7203), FE (P=0.4799), FI (P=0.2783), CF (P=0.5071) or SGR (P=0.7429). Furthermore, temperature did not influence protein efficiency ratio (P=0.0633), lipid efficiency ratio (P=0.0630), protein productive value (P=0.0756), energy productive value (P=0.1048), and lipid productive value (P=0.1386), however, diet had significant main effects on PER (P=0.0076), LPV (P=0.0075), and PPV (P=0.0138). Temperature regimens induced increased activities of mitochondrial complexes I (P=0.0120), II (P=0.0008), III (P=0.0010), IV (P<0.0001), V (P<0.0001) and citrate synthase (CS) (P<0.0001) in the intestine; complexes I (P<0.0001), II (P<0.0001) and CS (P=0.0122) in the muscle; and complexes I (P<0.0001), II (P<0.0001) and III (P<0.0001) in the liver. Similarly, dietary composition significantly affected complexes I (P<0.0001), II (P<0.0001), IV (P<0.0001), V (P<0.0001) and CS (P<0.0001) in the intestine; complexes I (P<0.0001), II (P<0.0001), III (P=0.0002), IV (P<0.0001), V (P=0.0060) and CS (P<0.0001) in the muscle; and complexes I (P<0.0001), II (P<0.0001), IV (P<0.0001), V (P<0.0001) and CS (P<0.0001) in the liver activities except complex III activities in intestine (P=0.0817) and liver (P=0.4662). The diet x temperature interaction impacted CS activity in the intestine (P=0.0010), complex II in the muscle (P = 0.0079) and complexes I (P=0.0009) and II (P=0.0348) in the liver. Overall, comparing partial to full dietary substitution of FO with CO, partial dietary replacement showed similar effects on complex activities.

The chemical nutrient composition and the phytochemical content of the leaves of Mucuna poggei, an underutilized leafy vegetable were analyzed using standard methods. The result of the proximate compositions analysis showed that the leaves contained moisture (8.25%), crude fibre (30.55%), crude fat (9.45%), ash (7.78%), crude protein (32.38%) and carbohydrate (11.55%). Results of the mineral analysis showed that it contains the following essential minerals: Sodium (68.10mg/100g), potassium (43.21mg/100g), calcium (71.71mg/100g), iron (10.56mg/100g), manganese (0.65mg/100g), copper (0.47mg/100g), magnesium (56.05mg/100g), zinc (0.25mg/100g), phosphorus (5.72mg/100g), lead (0.01mg/100g), cobalt (nil) and cadmium (nil). The high protein and fibre contents as well as other proximate components are a desirable attribute. The concentration of iron shows that Mucuna poggei leaves could help in boosting of blood level in anaemic conditions. The phytochemical screening of the leaves revealed the presence of alkaloids, tannins, carbohydrates, terpenoids, balsams and triterpenoids. These results rank the leaves of Mucuna poggei among the best in terms of essential nutrients composition when compared with those of other edible leaves in literature.