The objective of this research was to evaluate palatability, plasma biochemistry, antioxidative and anti-inflammatory capacity, and immune levels in cats by feeding supplementing inclusion of different levels of a mixture of protein hydrolysate from black soldier fly larvae and schizochytrium (BSFPs) in diets. In the feed experiment, a total of 24 adult cats (12 females and 12 males; BW: 3.02 ± 0.06 kg) were randomly divided into four groups: (1) diet with chicken and fish meal as primary protein resource (CON); (2) diet with 5% BSFPs replacing chicken meal, fish meal, chicken oil, and fish oil (5% BSFPs); (3) 10% BSFPs; and (4) 15% BSFPs. The body weight and feed intake were recorded, and a blood sample was collected for analysis. In the palatability experiment, three diets containing 5%, 10%, and 15% BSFPs were evaluated by comparing with CON. These results suggested that different levels of BSFPs could improve palatability in cat diets by enhancing the first sniff, the first bite, and feed intake (p < 0.05). However, no significant influence existed in body weight and average daily feed intake (p > 0.05). In comparison to the CON group, 5% and 15% BSFPs significantly increased the total protein content, and all treatment groups decreased the triglyceride content and enhanced the calcium concentration in plasma; in addition, the activity of aspartate aminotransferase and alanine aminotransferase and the content of creatinine and urea nitrogen were significantly reduced by the supplementation inclusion of BSFPs in the diets (p < 0.05). The enzyme activity of glutathione peroxidase was dramatically enhanced by the supplementation of 10% and 15% BSFPs in diets compared with the CON diet, and the activity of superoxide dismutase was increased and the malondialdehyde concentration was remarkably reduced in all three treatments (p < 0.05). Compared with the CON group, different levels of BSFPs in the diets significantly increased the immunoglobulin A content in plasma; similarly, the immunoglobulin G concentration was significantly enhanced by the supplementation of 10% and 15% BSFPs in the diets (p < 0.05). Furthermore, the interleukin-1β content was significantly reduced in the inclusion of 10% and 15% BSFPs in the diets, and 15% BSFPs remarkably decreased the content of interleukin-8 in plasma compared with the CON diet (p < 0.05). To sum up, the supplementation of different levels of BSFPs exhibited a positive effect on palatability and enhanced the antioxidant, anti-inflammatory, and immune capacity. Particularly, the addition levels of 10% and 15% BSFPs were more effective in antioxidation, anti-inflammation, and immunity.

Protein hydrolysate from black soldier fly larvae (BSFP) has garnered great attention with its lower allergenicity, high amount of essential amino acids, and small bioactive peptides. Schizochytrium is a promising alternative source of n-3 FUFA because it has enriched docosahexaenoic acid (DHA, C22: 6). The aim of this study was to assess palatability, the presence of diarrhea, plasma biochemistry panels, anti-oxidative and anti-inflammatory effects, and immune function in beagle dogs when supplementing a mixture of protein hydrolysate from black soldier fly larvae and schizochytrium (BSFPs) into their diets. Experiment I: 24 young beagle dogs (16 males and 8 females; 4–5 months; BW: 6.40 ± 0.15 kg) were randomly divided into four groups: (1) control (CON), (2) 5% BSFPs, (3) 10% BSFPs, (4) 15% BSFPs. Their body weights and fecal scores were recorded, and blood samples were collected for analysis. Experiment II: three diets containing 5%, 10%, and 15% BSFPs were evaluated by comparing them with a basal diet (CON) to evaluate palatability. These results suggested that a lower presence of diarrhea existed in the BSFP diet than the CON diet (p < 0.05). Three treatment groups remarkably increased their total protein (TP) and albumin (ALB) contents and decreased their concentrations of triglyceride (TG) and total cholesterol (TC) in plasma (p < 0.05). Moreover, the 5% and 15% BSFPs groups had a higher calcium (CA) content in plasma, and the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and contents of creatinine (CREA) and urea nitrogen (BUN) were significantly reduced by supplementing BSFP in their diets (p < 0.05). Their anti-oxidative enzyme activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were dramatically enhanced, and their malondialdehyde (MDA) concentrations were remarkably reduced (p < 0.05). Immunoglobulin A and G (IgA and IgG) concentrations in the plasma in the 10% and 15% BSFPs groups were significantly increased (p < 0.05). Furthermore, lower interleukin-8 (IL-8) contents were shown in the BSFP diets than the CON diet (p < 0.05). Similarly, the diets supplemented with BSFPs exhibited a positive effect on palatability (p < 0.05). To sum up, the diets supplemented with BSFPs significantly enhanced palatability, immune function, and anti-oxidative and anti-inflammatory capacity to alleviate diarrhea and improve the general health of the beagle dogs.

The enzyme-treated soybean protein (ETSP) could improve their application as an ingredient and substitute for fishmeal (FM) in aquafeeds. In the present research, an eight-week feeding trial was carried out to investigate the effects of using ETSP as a particle substitution in FM on growth performance, serum biochemical indices, antioxidant, intestinal barrier integrity and relative mRNA expression levels in largemouth bass (Micropterus salmoides). A cohort of 450 fish (15.52 ± 0.04 g/fish) were randomly divided into five groups with five replacement levels of ETSP: 0, 12.5, 25.0, 37.5 and 50.0% (control, H2-12.5, H2-25.0, H2-37.5 and H2-50.0). Results showed that final body weight (FBW), weight gain (WG), and specific growth rate (SGR) reach the highest value, and the feed conversion ratio (FCR) reaches lowest in H2-25.0 group. The activities of total superoxide dismutase (T-SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were remarkably increased by replacing FM with ETSP at certain level, while malondialdehyde (MDA) concentration significantly decreased (p < 0.05). Higher levels of total protein (TP) and albumin (ALB) as well as lower activity of aspartate aminotransferase (AST) were detected with ETSP replacement. Histological examination revealed that villus height in mid-intestine was the highest, while this factor in pyloric caeca was not affected. The activity of diamine oxidase (DAO) and the contents of D-lactate (D-Lac) and lipopolysaccharide (LPS) in serum were gradually decreased when replacing FM with ETSP in the diets. In addition, replacement of FM with ETSP at 25% improved intestinal barrier function by upregulating gene expression related to the tight junctions (occludin, claudins, ZO-1 and ZO-2) and anti-inflammatory cytokines (IL-10) while downregulating pro-inflammatory factors (IL-8 and TNFα). Moreover, proper amount of ETSP instead of FM can upregulate mRNA expression of LAT1, PEPT1 and PEPT2 in the intestine. In conclusion, at the fishmeal level used in the diet tested in the present study, 25% replacement is the most beneficial for juvenile largemouth bass.