Soybean meal allergenic protein degradation and gut health of piglets fed protease-supplemented diets

Dietary Protease Supplementation Improved Growth Performance and Nutrients Digestion via Modulating Intestine Barrier, Immunological Response, and Microbiota Composition in Weaned Piglets

Despite mounting evidence for dietary protease benefits, the mechanisms beyond enhanced protein degradation are poorly understood. This study aims to thoroughly investigate the impact of protease addition on the growth performance, intestinal function, and microbial composition of weaned piglets. Ninety 28-day-old weaned pigs were randomly assigned to the following three experimental diets based on their initial body weight for a 28-day experiment: (1) control (CC), a basic diet with composite enzymes without protease; (2) negative control (NC), a diet with no enzymes; and (3) dietary protease (PR), a control diet with protease. The results show that dietary proteases significantly enhanced growth performance and boosted antioxidant capacity, increasing the total antioxidant capacity (T-AOC) levels (p < 0.05) while reducing malonaldehyde levels (p < 0.05). Additionally, protease addition reduced serum levels of inflammatory markers TNF-α, IL-1β, and IL-6 (p < 0.05), suppressed mRNA expression of pro-inflammatory factors in the jejunum (p < 0.01), and inhibited MAPK and NF-κB signaling pathways. Moreover, protease-supplemented diets improved intestinal morphology and barrier integrity, including zonula occludens protein 1(ZO-1), Occludin, and Claudin-1 (p < 0.05). Microbiota compositions were also significantly altered by protease addition with increased abundance of beneficial bacteria (Lachnospiraceae_AC2044_group and Prevotellaceae_UCG-001) (p < 0.05) and reduced harmful Terrisporobacter (p < 0.05). Further correlation analysis revealed a positive link between beneficial bacteria and growth performance and a negative association with inflammatory factors and intestinal permeability. In summary, dietary protease addition enhanced growth performance in weaned piglets, beneficial effects which were associated with improved intestinal barrier integrity, immunological response, and microbiota composition.

Rosmarinic acid mitigates intestinal inflammation and oxidative stress in bullfrogs (Lithobates catesbeiana) fed high soybean meal diets

High proportions of soybean meal in aquafeed have been confirmed to induce various intestinal pathologies. This study aims to investigate the regulatory effects of rosmarinic acid (RA), an antioxidant with anti-inflammatory and antimicrobial properties, when added to high soybean meal feeds in different doses, (0, 0.5, 1, and 4 g/kg). During the 56-day feeding trial, results indicated that, compared to the control group without RA (0 g/kg), the 1 g/kg and 4 g/kg RA groups increased bullfrog survival rates and total weight gain while reducing feed coefficient. Additionally, these doses markedly suppressed the expression of key intestinal inflammatory markers (tlr5, myd88, tnfα, il1β, cxcl8, cxcl12) and the activity and content of intestinal antioxidants (CAT, MDA, GSH, GPX). Concurrently, RA significantly downregulated the transcription levels of antioxidant-related genes (cat, gpx5, cyba, cybb, mgst, gclc, gsta, gstp), suggesting RA's potential to alleviate intestinal inflammation and oxidative stress induced by high soybean meal and to help downregulate and restore normal expression of antioxidant enzyme genes. However, the 0.5 g/kg RA group did not show a significant improvement in survival rates; instead, it upregulated the transcription of some antioxidant genes (cat, gpx5, cyba, cybb), revealing the complexity and dose-dependency of RA's antioxidant action. Furthermore, RA supplementation significantly reshaped the intestinal microbial community structure and relative abundance in bullfrogs, particularly affecting the genera Hafnia, Phascolarctobacterium, and Lactococcus. Notably, high doses of RA (1 g/kg, 4 g/kg) were able to downregulate pathways associated with the enrichment of gut microbiota in diseases such as Parkinson's, Staphylococcus aureus infection, and Systemic lupus erythematosus, suggesting its potential in anti-inflammatory action and health maintenance to prevent potential diseases.

Dietary nutrition, intestinal microbiota dysbiosis and post-weaning diarrhea in piglets

Weaning is a critical transitional point in the life cycle of piglets. Early weaning can lead to post-weaning syndrome, destroy the intestinal barrier function and microbiota homeostasis, cause diarrhea and threaten the health of piglets. The nutritional components of milk and solid foods consumed by newborn animals can affect the diversity and structure of their intestinal microbiota, and regulate post-weaning diarrhea in piglets. Therefore, this paper reviews the effects and mechanisms of different nutrients, including protein, dietary fiber, dietary fatty acids and dietary electrolyte balance, on diarrhea and health of piglets by regulating intestinal function. Protein is an essential nutrient for the growth of piglets; however, excessive intake will cause many harmful effects, such as allergic reactions, intestinal barrier dysfunction and pathogenic growth, eventually aggravating piglet diarrhea. Dietary fiber is a nutrient that alleviates post-weaning diarrhea in piglets, which is related to its promotion of intestinal epithelial integrity, microbial homeostasis and the production of short-chain fatty acids. In addition, dietary fatty acids and dietary electrolyte balance can also facilitate the growth, function and health of piglets by regulating intestinal epithelial function, immune system and microbiota. Thus, a targeted control of dietary components to promote the establishment of a healthy bacterial community is a significant method for preventing nutritional diarrhea in weaned piglets.

Integrated Transcriptome and Proteome Analyses of β-Conglycinin-Induced Intestinal Damage in Piglets

β-conglycinin (β-CG) induces intestinal damage in piglets; however, its regulatory mechanisms are not fully understood. This study aimed to investigate the molecular mechanisms by which β-CG regulates intestinal injury in piglets through downstream genes and proteins. Our findings revealed that β-CG significantly reduced villus height while increasing the crypt depth. In addition, we analyzed the transcriptome and proteome of jejunum tissues after the β-CG treatment. In total, 382 differentially expressed genes (DEGs) and 292 differentially expressed proteins (DEPs) were identified between the treatment and the control groups. The expression levels of DEGs and DEPs were validated by using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blotting, respectively. The findings revealed a consistent correlation between their expression levels and transcriptomic and proteomic data. In addition, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of DEGs and DEPs revealed their enrichment in oxidation-related GOs, as well as in lysosome-related pathways. A protein-protein interaction (PPI) regulatory network was constructed based on the DEPs. The integration of transcriptomic and proteomic analyses identified six genes that were significantly different at both the transcript and the protein levels. This study provides valuable insights into the molecular mechanisms underlying β-CG-induced intestinal injury in piglets.

Effects of crude protease produced by Bacillus subtilis (MAFIC Y7) on growth performance, immune indices, and anti-inflammatory responses of broilers fed soybean meal- or cottonseed meal-based diets

A strain of Bacillus subtilis (MAFIC Y7) was isolated from the intestine of Tibetan pigs and was able to express high protease activity. The aim of this study was to characterize the proteases produced by MAFIC Y7, and to investigate the effects of protease addition on growth performance, ileal amino acid digestibility, and serum immunoglobulin and immune factors of broilers fed SBM-based diets, or on growth performance, carcass characteristics, and intestinal morphology of broilers fed CSM-based diets. B. subtilis (MAFIC Y7) expressed protease showed its optimal enzyme activity at 50 °C and pH 7.0. The coated crude enzyme (CCE) showed greater stability at pH 3.0 than its uncoated counterpart. Experiment 1 was conducted with six diets based on three levels of crude protein (CP)-CPlow, CPmedium, and CPhigh-with or without CCE. In CPlow, CCE increased gain:feed (G:F) (days 1 to 21, days 1 to 42) by 8%, 3%, respectively, and enhanced apparent ileal digestibility (AID) of crude protein and lysine (on day 42) by 8.8%, 4.6%, respectively, compared with diets containing no CCE (P < 0.05). CCE increased G:F from days 1 to 21 from 0.63 to 0.68, improved G:F and average daily gain (ADG) during days 1 to 42, and enhanced AID of crude protein, lysine, cysteine, and isoleucine on day 42 compared with the unsupplemented treatments (in CPmedium, P < 0.05). CCE increased serum IgA (on day 21), serum IgA and IgG and increased serum IL-10 (on day 42), but decreased serum tumor necrosis factor-α (TNF-α; on day 21), and serum IL-8 and TNF-α (on day 42) compared with unsupplemented treatments. At CPhigh, CCE decreased serum levels of IL-6 and TNF-α (on day 21), and IL-8 and TNF-α (on day 42) compared with unsupplemented treatments (in CPhigh, P < 0.05). In experiment 2, CSM-based diets with two lysine-to-protein ratios (5.2% or 5.5%) with or without CCE. In the high Lys diet (5.5% Lys:protein), CCE increased ADG and G:F, increased carcass, but decreased abdominal fat compared with the unsupplemented treatment (P < 0.05). In the 5.2% Lys:protein dietary treatment, CCE improved duodenal villus height compared with the unsupplemented treatment (P < 0.05). Supplementation of protease produced by MAFIC Y7 was associated with lower inflammatory responses in SBM diets (CPmedium or CPhigh) and improved ADG in broilers fed CPmedium or CPhigh. The proteases improved ADG and the efficiency of CSM use when the ratio of Lys to protein was 5.5%.

Modification of Gut Microbiota and Immune Responses via Dietary Protease in Soybean Meal-Based Protein Diets

Plant-based protein sources such as soybean meal have low digestibility and are generally promoted accumulation of undigested proteins into the intestine by enzymatic treatments. Moreover, potential intestinal pathogens ferment undigested proteins, producing harmful substances, such as ammonia, amines and phenols, leading to an overactive immune response and diarrhea in weaned pigs. As a solution, dietary proteases hydrolyze soybean-based antinutritive factors, which negatively affect immune responses and gut microbiota. In this study, we investigated the effects of dietary proteases (PRO) in a low-crude protein (CP) commercial diet on the immune responses and gut microbiota of weaned pigs. The experimental design consisted of three dietary treatments: a commercial diet as a positive control (PC; phase1 CP = 23.71%; phase 2 CP: 22.36%), a lower CP diet than PC as negative control (NC; 0.61% less CP than PC), and NC diet supplement with 0.02% PRO. We found that PRO tended to decrease the frequency of diarrhea in the first two weeks after weaning compared with PC and NC. In addition, pigs fed PRO showed decreased TNF-α and TGF-β1 levels compared with those fed PC and NC. The PRO group had a higher relative proportion of the genus Lactobacillus and lower levels of the genus Streptococcus than the PC and NC groups. In conclusion, the addition of PRO to a low CP commercial weaned diet attenuated inflammatory responses and modified gut microbiota in weaned pigs.

Effects of dietary supplementation with essential oils and protease on growth performance, antioxidation, inflammation and intestinal function of weaned pigs

This experiment evaluated the impacts of essential oils (EO) and protease (PRO), independently or in combination, on growth performance, antioxidation, inflammation and intestinal function of weaned pigs. One hundred and sixty weaned pigs (21 d of age, BW of 6.74 ± 0.20 kg) were randomly divided into 4 treatments with 8 replicate pens of 5 pigs per pen. Dietary treatments included the following: 1) control diet (CON), 2) CON with 300 mg/kg essential oils (EO), 3) CON with 500 mg/kg protease (PRO), 4) CON with 300 mg/kg essential oil and 500 mg/kg protease (EO + PRO). On d 8, one pig from each pen was selected for sampling. The remaining pigs were fed for an additional week and growth performance was monitored during this period. Dietary treatments had no marked effects (P > 0.05) on the growth performance of pigs. However, pigs receiving EO diet had higher (P < 0.05) serum glutathione peroxidase (GSH-Px) activity, and tended to decrease (P = 0.063) serum concentration of tumor necrosis factor-α (TNF-α). In addition, pigs receiving EO diet had higher (P < 0.05) abundances of phylum Actinobacteria, and genera Bifidobacterium, and lower (P < 0.05) phylum Bacteroidetes and genera Alloprevotella in colonic digesta. Pigs receiving PRO diet decreased (P < 0.05) the serum concentration of malondialdehyde (MDA) and diamine oxidase activity, increased (P < 0.05) the villus height and the ratio of villus height to crypt depth in duodenum, increased sucrase activity in jejunal mucosa, and also increased the abundance of phylum Actinobacteria in colonic digesta. Furthermore, the synergistic effects of EO and PRO was observed (P < 0.05) for pigs with decreasing serum TNF-α concentration and increasing serum GSH-Px activity. Collectively, the results indicated that dietary supplementation of EO and PRO had no significant effects on growth performance of weaned pigs. EO diet appeared to improve antioxidant activity and intestinal microbiota, while PRO diet improved intestinal morphology and digestive enzyme activity, and there was a synergistic effect of EO and PRO on reducing inflammatory parameters in weaned pigs.

Full-fat field cricket (Gryllus bimaculatus) as a substitute for fish meal and soybean meal for weaning piglets: effects on growth performance, intestinal health, and redox status

Full-fat field cricket meal (FCP) is an alternative protein ingredient in livestock production; however, the effects of replacing conventional protein sources with FCP in nursery diets have not been determined. In this study, the effects of the partial replacement of either fish meal or soybean meal with FCP on weaning pigs were evaluated, including the analyses of growth performance, nutrient utilization, intestinal morphology, 
immunity, oxidative stress, and fecal microbial counts. A total of 100 crossbred weaning pigs [(Landrace × Large White) × Duroc] were allotted to one of the following five treatments with five replicates (four pigs/pen) and fed for 28 d postweaning. Treatments were 1) a corn-soybean meal (SBM)-based diet with 5% fish meal (Positive control; PC), 2) a corn-SBM-based diet without fish meal (Negative control; NC), 3) field crickets replacing fishmeal on a total Lys basis (FCP1), 4) field crickets replacing fishmeal on a kg/kg basis (FCP2), and 5) field crickets replacing fish meal and soybean meal (FCP3). The piglets on FCP1 had a higher body weight on days 14 and 28, and an increased average daily gain over the experimental period than NC (P < 0.05); FCP2 and FCP3 were similar to the FCP1 treatment. The incidence of diarrhea was lower under an FCP-supplemented diet than under the NC diet throughout the study (P < 0.05). Pigs fed FCP1 and FCP2 had a higher digestibility of crude 
protein (P = 0.041), and all FCP groups increased crude fat digestibility (P = 0.024). FCP1 and FCP2 also increased jejunal villus height 
(P = 0.009), whereas the increase in jejunal villus-to-crypt ratios (P = 0.019) was greater in pigs fed the FCP2 diet than those fed the NC diet. Furthermore, FCP2 supplementation increased serum immunoglobulin A levels on days 14 and 28, including reduced serum interleukin-6 and tumor necrosis factor alpha levels (P < 0.05). Pigs fed an FCP2 diet had reduced malondialdehyde levels than those fed a PC diet, while pigs fed an FCP2 diet had higher superoxide dismutase and glutathione peroxidase levels, and more fecal Lactobacillus spp. than those fed an NC diet (P < 0.05). These results support the use of FCP as an alternative protein ingredient with beneficial effects on growth performance, intestinal morphology, antioxidant capacity, and intestinal microbiota. In particular, FCP can be used as a partial substitute for fish meal and soybean meal without detrimental effects on weaning pigs.

Bacillus amyloliquefaciens 35 M can exclusively produce and secrete proteases when cultured in soybean-meal-based medium

Some microbial strains are ideal producers of extracellular enzymes that can be used in various industries. However, in many fields, especially in the pharmaceutical field, these enzymes need to be recovered and purified through multistep processes and tedious procedures before they can be used. The recovery process is difficult and increases the cost of enzyme production. Therefore, reducing purification steps will greatly benefit the utilization of microbial enzymes. The 35 M strain of Bacillus amyloliquefaciens, which has high extracellular protease production, was isolated from a phosphate mine. When cultured in a medium with soybean meal as the main component, the maximum activity of extracellular protease reached 16,992 U/mL. SDS-PAGE showed that there were two main proteins in the fermentation supernatant, with a paucity of other defined protein bands. Mass spectrometry and zymogram analysis showed that the two main bands were two proteases, corresponding to alkaline protease (AprM) and neutral protease (NprM), respectively. Gene cloning, sequencing, and further comparisons were used to confirm AprM and NprM correspond to these proteases from B. amyloliquefaciens. Notably, SDS-PAGE and zymogram analysis showed that NprM had obviously higher catalytic efficiency toward casein than did AprM. Strain 35 M is a promising protease producer with great potential for applications in industrial protease production. Additionally, this study demonstrates strain 35 M may be particularly well suited to use in degrading anti-nutritional factors in soybean meal, so as to improve the nutritional value of soybean meal.

Comparative effects of enzymatic soybean, fish meal and milk powder in diets on growth performance, immunological parameters, SCFAs production and gut microbiome of weaned piglets

Background

The objective of this study was to evaluate the replacement effects of milk powder (MK) and fish meal (FM) by enzymatic soybean (ESB) in diets on growth performance, immunological parameters, SCFAs production and gut microbiome of weaned piglets.

Methods

A total of 128 piglets with initial body weight at 6.95 ± 0.46 kg, were randomly assigned into 4 dietary treatments with 8 replicates per treatment and 4 piglets per replicate for a period of 14 d. Piglets were offered iso-nitrogenous and iso-energetic diets as follows: CON diet with MK and FM as high quality protein sources, ESB plus FM diet with ESB replacing MK, ESB plus MK diet with ESB replacing FM, and ESB diet with ESB replacing both MK and FM.

Results

No significant differences were observed in growth performance among all treatments (P > 0.05). However, piglets fed ESB plus FM or ESB diet had increased diarrhea index (P<0.01), and lower digestibility of dry matter (DM), gross energy (GE) or crude protein (CP), relative to piglets fed CON diet (P <  0.01). Moreover, the inclusion of ESB in diet markedly decreased the plasma concentration of HPT and fecal concentration of butyric acid (BA) (P<0.01). The High-throughput sequencing of 16S rRNA gene V3−V4 region of gut microbiome revealed that the inclusion of ESB in diet increased the alpha diversity, and the linear discriminant analysis effect size (LEfSe) showed that piglets fed with ESB plus FM or ESB diet contained more gut pathogenic bacteria, such as g_Peptococcus, g_Veillonella and g_Helicobacter.

Conclusion

The inclusion of ESB in diet did not markedly affect growth performance of piglets, but the replacement of MK or both MK and FM by ESB increased diarrhea index, which could be associated with lower nutrients digestibility and more gut pathogenic bacteria. However, piglets fed diet using ESB to replace FM did not markedly affect gut health-related parameters, indicating the potential for replacing FM with ESB in weaning diet.

Protease supplementation attenuates the intestinal health damage caused by low-protein diets in Pekin ducks

The objective of this study was to investigate the effects of low-protein diets with low digestibility of feed ingredients on intestinal damage and to explore whether the protease supplementation can alleviate the damage in Pekin ducks. A total of 576 Pekin ducklings (6 replicate pens, 16 ducks/pen) were randomly assigned to 6 dietary treatments (3 × 2 factorial arrangement) in a randomized complete block design. Factors were CP levels (13.5%, 15.5%, and 17.5%) and protease (0 or 20,000U/kg). Compared with the diets containing 17.5% CP, low-protein diets (13.5% CP) showed suppressed (P < 0.05) growth performance and feed intake (FI); reduced (P < 0.05) serum-free arginine, isoleucine, leucine, methionine, phenylalanine, valine, and proline as well as the cecal acetate and propionate concentration; increased (P < 0.05) plasma and ileal mucosal tumor necrosis factor-α (TNF-α) concentration; and downregulated (P < 0.05) mRNA expression of TNF-α, nuclear transcription factor-κb, interferon gamma, and Occludin in ileal mucosa. Irrespective of the dietary CP levels, protease supplementation significantly increased (P < 0.05) the serum-free glutamic acid concentration while decreasing (P < 0.05) the plasma endotoxin, IL-6, and the cecal isovalerate concentration. A significant interactive effect was observed between low-protein diets and protease supplementation (P < 0.05) on serum-free arginine concentration, the ratio of ileal villus height to crypt depth, and the IL-6 concentration in ileal mucosa. These results indicated that low-protein diets could damage intestinal integrity to induce systemic inflammation response and at last to suppress growth performance. Protease supplementation could partly attenuate the negative effects on gut health caused by low-protein diets in Pekin ducks.