Effect of dietary β-mannanase supplementation on growth performance, digestibility, and gene expression levels of Cyprinus carpio (Linnaeus) fingerlings fed a plant protein-rich diet

Effect of Supplementing Exogenous Glucanase or/and Mannanase to Diets Containing Torula Yeast on Growth Performance, Biochemical Indices, Liver and Intestinal Morphology, and Intestinal Microbiota and Metabolism of Largemouth Bass (Micropterus salmoides)

In the current study, we investigated the effect of a basic diet (where 20% of fishmeal was replaced by torula yeast, referred to as the control group), supplementation with β-glucanase (1000 U·kg-1, referred to as the TYG group), β-mannanase (510 U·kg-1, referred to as the group), and their combination (TYGM group), on the growth and health of juvenile largemouth bass (Micropterus salmoides). After an 8-week feeding experiment, the results revealed that juveniles in the TYM and TYGM groups exhibited significantly higher specific growth rates and hepatic antioxidant capacity, along with notably reduced levels of alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase activities in their serum. Histomorphological assessment indicated that dietary glucanase and/or mannanase could mitigate vacuolization and nuclear deviation in the liver, while also increasing villus width and height. Furthermore, 16S rRNA sequence analysis revealed a significant decrease in Mycoplasma levels in the TYM and TYGM groups, along with a notable increase in Cetobacterium content in the TYGM group compared to the other groups. Additionally, untargeted metabolomics analysis showed that the differentially expressed metabolites were primarily correlated with lipid metabolism, including steroid hormone biosynthesis (cholesterol sulfate), primary bile acid biosynthesis (cerebrosterol), and sphingolipid metabolism (phytosphingosine) between the control and TYGM groups. In conclusion, our study demonstrated that dietary glucanase + mannanase could partially alleviate the adverse impacts on the growth and health of juveniles caused by high levels of torula yeast in the diet.

Effects of rosemary extract and its residue on production, immune performance, and gut microbiota in geese

Introduction

To explore the effects of rosemary extract (RE) and its residue (RR) on the production, immune performance, and gut microbiota of geese.

Methods

We treat 28-day-old Sichuan white geese (n = 180) with three diets: (1) basal diet (control), (2) basal diet supplemented with 0.02% RE, and (3) basal diet supplemented with 15% RR for 42 days.

Results and discussion

On day 70, compared with control treatment, the final body weight, average daily gain and lysozyme levels in the RE treatment increased significantly (p < 0.05). In the RE and RR treatments, there was a significant decrease in alkaline phosphatase, globulin, and high-density lipoprotein levels compared to the control treatment, and there was also a significant increase in aspartate aminotransferase/alanine aminotransferase (p < 0.05). Moreover, for both RE and RR treatments, semi-eviscerated, eviscerated weights, and calcium apparent digestibility increased significantly, along with a decrease in the duodenal index (p < 0.05). Compared with RE treatment, those in the RR treatment had significantly higher duodenal and jejunum relative lengths, aspartate aminotransferase, uric acid, total cholesterol, and low-density lipoprotein levels, and decreased chest depth, chest angle, neck length, semi-eviscerated and eviscerated weights, crude protein digestibility, and levels of globulin, triglyceride, and lysozyme (p < 0.05). There were no differences in gut microbiota α or β diversities among treatments (p > 0.05). Compared to the control treatment, the relative abundance of Turicibacter significantly increased in the RR and RE treatments, and the relative abundance of Sporobacter, Alistipes, and Barnesiella significantly increased in the RR treatment (p < 0.05). Rikenellaceae, Succinivibrionaceae, and Aeromonadales were enriched in the RR treatment, and Lachnospiraceae, Turicibacteraceae, Fusobacteriaceae, and Enterobacteriaceae were enriched in the RE treatment. While we demonstrate the RR diet to be less effective than the RE diet, it did improve production and the gut microbiota of geese to a certain extent.

Dietary β-Mannanase Affects the Growth, Antioxidant, and Immunes Responses of African Catfish, Clarias gariepinus, and Its Challenge Against Aeromonas hydrophila Infection

One of the most farmed fishes is the African catfish, Clarias gariepinus. Its production has increased by 20% annually on average during the last 20 years, but the occurrence of fish diseases, especially bacterial such as Aeromonas hydrophila infections, is hindering its activities. Also, the incorporation of plant-derived substances in aquafeeds is limited since they frequently contain different antinutritional factors, like nonstarch polysaccharides (NSPs). However, supplementing fish diets with β-mannanase could increase growth, antioxidants, and immunity. Despite the advantage of β-mannanase, its effects on growth, digestive enzymes, antioxidants, and immunity in African catfish need to be elucidated. This study examined the effects of dietary β-mannanase on the growth performance, liver enzymes, antioxidant profiles, immunity, and protection of African catfish, C. gariepinus, against A. hydrophila infection. Five isonitrogenous diets were prepared to have 400 g/kg crude protein and supplemented with β-mannanase at 0, 1500, 3000, 4500, or 6000 thermostable endo, 1,4-β-mannanase units (TMUs)/kg diet and fed to 300 juveniles of the African catfish, C. gariepinus (mean weight 12.1 ± 0.1 g) for 12 weeks. Then, 10 fish from each tank received an intraperitoneal injection of 0.1 mL of A. hydrophila (5.0 × 105 CFU/mL) and observed for 14 days. Results showed dietary β-mannanase levels considerably improved growth performance but did not affect fish survival. Also, amylase, protease, and lipase levels were significantly promoted in the fish fed with β-mannanase-fortified diets than the control group (p  < 0.05). Enhanced gut villi and intestinal absorption areas, haematlogical profiles, and liver enzymes but reduced gut viscosity were observed in fish-fed β-mannanase-fortified diets (p  < 0.05). In a dose-dependent order, including β-mannanase in the meals of African catfish raised the levels of glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione-S-transferase (GST), and glutamate cysteine ligase (GCL) activities and decreased the malondialdehyde (MDA) values in African catfish (p  < 0.05). Also, fish immunity was greatly (p  < 0.05) enhanced due to supplementation of the diet with β-mannanase. In addition, fish-fed diets comprising 6000 TMU β-mannanase/kg diet showed the lowest rates of fish mortality (7.5%) (p  < 0.05). Therefore, feeding African catfish, Clarias gariepinus, β-mannanase enhanced growth performance, increased activity of digestive enzymes, gut morphology, enhanced generation of short-chain fatty acids, digesta potential of hydrogen (pH), and improved antioxidant profiles and immunity at the optimum dose of 5800 TMU/kg diet. Additionally, β-mannanase protected African catfish against A. hydrophila infection.

Analysis of the effects of β-mannanase on immune function and intestinal flora in broilers fed the low energy diet based on 16S rRNA sequencing and metagenomic sequencing

As an enzyme, β-mannanase (BM) can be widely used as feed additive to improve the growth performance of animals. This experiment aimed to determine the effect of the addition of BM to low-energy diet on the immune function and intestinal microflora of broiler chickens. In this study, 384 one-day-old Arbor Acres broilers were randomly divided into 3 groups (8 replicates per group): positive control (PC, received a corn-soybean meal basal diet), negative control (NC, received a low-energy diet with Metabolizable Energy (ME) reduced by 50 kcal/kg) and NC + BM group (NC birds + 100 mg/kg BM). All birds were raised for 42 d. The results showed that BM mitigated the damage of immune function in peripheral blood of broilers caused by the decrease of dietary energy level by increasing the Concanavalin A (Con A) index of stimulation (SI) and macrophages phagocytic activity in the peripheral blood of broilers at 42 d (P < 0.05). The analysis of cecum flora showed that the low-energy diet significantly reduced the observed_species index (P < 0.01), Chao1 index and ACE index (P < 0.05), which reduced the abundance and evenness of species in the cecum of broilers at 21 d. It also significantly reduced the relative abundance of Candidatus_Arthromitus and significantly increased the relative abundance of Pseudomonas in the cecum of broilers at 21 d, while also significantly increasing the relative abundance of Monoglobus at 42 d. BM significantly increased the relative abundance of Lachnospiraceae_UCG-001 and Lachnospiraceae_bacterium_615 in the cecum of broilers at 21 d. In addition, BM inhibited microbial Fatty acid degradation by decreasing the activity of glutaryl-CoA dehydrogenase. Collectively, BM could improve intestinal health by enhancing the immune function of broilers, promoting the proliferation of beneficial bacteria and reducing the number of harmful bacteria, regulating intestinal flora, thereby alleviating the adverse effects of lower dietary energy levels.