Exogenous enzymes and probiotics alter digestion kinetics, volatile fatty acid content and microbial interactions in the gut of Nile tilapia.

Sustainable aquafeed production requires fishmeal replacement, leading to an increasing use of plant-derived ingredients. As a consequence, higher levels of antinutritional substances, such as non-starch polysaccharides and phytate, are present in aquafeeds, with negative effects on fish performance, nutrient digestibility and overall gut health. To alleviate these negative effects, providing exogenous digestive enzymes and/or probiotics can be an effective solution. In this study, we tested the effect of dietary supplementation of enzymes (phytase and xylanase) and probiotics (three strains of Bacillus amyloliquefaciens) on nutrient digestion kinetics and volatile fatty acid content along the gut, and the distal gut microbiome diversity in Nile tilapia. Chyme volatile fatty content was increased with probiotic supplementation in the proximal gut, while lactate content, measured for the first time in vivo in fish, decreased with enzymes along the gut. Enzyme supplementation enhanced crude protein, Ca and P digestibility in proximal and middle gut. Enzymes and probiotics supplementation enhanced microbial interactions as shown by network analysis, while increased the abundance of lactic acid bacteria and Bacillus species. Such results suggest that supplementation with exogenous enzymes and probiotics increases nutrient availability, while at the same time benefits gut health and contributes to a more stable microbiome environment.

Interactions between phytase and xylanase enzymes in male broiler chicks fed phosphorus-deficient diets from 1 to 18 days of age.

A total of 735 one-day-old male broiler chicks were used to evaluate the interactions between different levels of phytase and xylanase enzymes on performance and bone mineralization. Basal nonphytate P (nPP)-deficient diets (0.15%) were supplemented with different levels of phytase [0X, 1X, 2X, 3X, and 4X of recommended level (X = 500 phytase units per kg of feed)] alone or in combination with 3 levels of a xylanase preparation [0X, 1X, and 2X of recommended level (X = 0.1 g per kg of feed; a mixture with predominantly xylanase activity)]. A standard curve was developed using different levels of nPP (0.15 to 0.45%) to estimate the P equivalency of each enzyme combination. Treatments were replicated with 7 pens of 5 chicks each. The findings indicated that reducing dietary nPP level had a severely negative influence on bird performance and bone ash content. Results also showed that increasing levels of phytase significantly (P < 0.05) improved BW, feed intake, feed conversion ratio, mortality, and toe and tibia bone ash contents in a dose-dependent fashion. The P equivalency of phytase was also dose dependent, with estimates of 0.08, 0.11, 0.15, and 0.19 for 1X, 2X, 3X, and 4X supplementation levels of phytase, respectively. Xylanase preparation at 1X level failed to influence measured criterion; however, increasing the level of xylanase (2X) resulted in deteriorating BW and feed conversion ratio. The P equivalency of xylanase preparation at 1X and 2X was estimated as 0.010 and 0.014%. There were no interactions between phytase and xylanase preparation (P > 0.05). In conclusion, phytase was effective in improving bird performance and bone mineralization; however, xylanase supplementation failed to enhance phytase efficacy.

Interactive effects of phytase and xylanase supplementation with extractable salt-soluble protein content of corn in diets with adequate calcium and nonphytate phosphorus fed to broilers.

The objective was to determine the effects of extractable salt-soluble protein content of corn (PS) and exogenous enzyme supplementation on N, starch, and energy digestibility in broilers fed diets adequate in Ca and nonphytate P. Broilers were randomly distributed into floor pens (6 replicate pens per treatment) with 28 birds per pen at 1 d of age. Treatments consisting of 4 sources of corn varying in PS (A, 58.1; B, 54.2; C, 53.7; and D, 30.6 mg of BSA equivalent values) with or without phytase (0 and 1,000 phytase units/kg) and xylanase (0 and 16,000 units of xylanase activity/kg) were randomly assigned to each pen. Different sources of corn were provided from 1 to 9 and 24 to 29 d of age. However, enzyme treatments were provided throughout the experiment. From 1 to 9 d of age, no interactions were observed. Apparent ileal N digestibility (AIND) and apparent ileal digestible energy (IDE) of diets with the lowest PS (based on corn D) were lower (P ≤ 0.05) than those of diets with a higher PS. Phytase increased (P ≤ 0.01) AIND and IDE by 5 and 16%, respectively, and xylanase exerted the opposite effect (P ≤ 0.03). From 24 to 29 d of age, phytase and xylanase in combination resulted in reduced (P ≤ 0.05) AIND of diets with a low PS (based on corn D) compared with the basal diet in broilers. Broilers fed diets with the highest or lowest PS (based on corn A or D) had lower (3-way interaction; P ≤ 0.05) IDE when phytase and xylanase were supplemented in combination compared with either enzyme alone. In conclusion, responses to exogenous enzyme supplementation are not constant and are influenced by the source of ingredients as well as the age of broilers. The magnitudes of the responses to phytase on nutrient and energy digestibility were greater at 9 compared with 29 d of age.

Effects of an exogenous enzyme preparation on microbial protein synthesis, enzyme activity and attachment to feed in the Rumen Simulation Technique (Rusitec).

The effects of an exogenous enzyme preparation, the application method and feed type on ruminal fermentation and microbial protein synthesis were investigated using the rumen simulation technique (Rusitec). Steam-rolled barley grain and chopped alfalfa hay were sprayed with water (control, C), an enzyme preparation with a predominant xylanase activity (EF), or autoclaved enzyme (AEF) 24 h prior to feeding, or the enzyme was supplied in the buffer infused into the Rusitec (EI). Microbial N incorporation was measured using (15NH4)2SO4 in the buffer. Spent feed bags were pummelled mechanically in buffer to segregate the feed particle-associated (FPA) and feed particle-bound (FPB) bacterial fractions. Enzymes applied to feed reduced neutral-detergent fibre content, and increased the concentration of reducing sugars in barley grain, but not alfalfa hay. Ruminal cellulolytic bacteria were more numerous with EF than with C. Disappearance of DM from barley grain was higher with EF than with C, but alfalfa was unaffected by EF. Treatment EF increased incorporation of 15N into FPA and FPB fractions at 24 and 48 h. In contrast, AEF reduced the 24 h values, relative to C; AEF and C were similar at 48 h. Infused enzyme (EI) did not affect 15N incorporation. Xylanase activity in effluent was increased by EF and EI, compared to C, but not by AEF. Xylanase activity in FPA was higher at 48 h than at 24 h with all treatments; it was higher with EF than C at 24 and 48 h, but was not altered by AEF or EI. Applying enzymes onto feeds before feeding was more effective than dosing directly into the artificial rumen for increasing ruminal fibrolytic activity.

Toxicological assessment of recombinant xylanase X(22) in wine.

Toxicological evaluation of xylanase X(22) from Aspergillus nidulans expressed in a wine yeast strain was carried out. The safety of the X(22) intake was assessed by digestibility, bioinformatic, and mouse short-term repeated dosing studies, although X(22) shows resistance to proteolytic degradation in the gastrointestinal system, is a minority protein component (<0.5 10(-)(6) %) of the produced wine, and shows no significant amino acid sequence homology to any known food allergens. The 4-week oral toxicity study was performed in Swiss mice at a dose level of 0.01, 0.1, or 1 mg/kg/day (these dosages correlate to 8, 80, and 800 times, respectively, the enzyme amount contained in 250 mL of wine). Body weight, food and fluid intake, urinalysis, and hematology data were obtained. Postmortem examinations and histopathology by both light and electron microscopy were performed. According to the results of this study, no adverse effects were detected by oral administration of X(22).