The effects of restricting enzyme supplementation in wheat-based diets to broilers

Interactions between enzyme preparations and trace element sources on growth performance and intestinal health of broiler chicks

This experiment was conducted to explore the interactions between enzyme preparations and trace element sources on growth performance and intestinal health of broilers chicks. A total of 480 one-day-old healthy male yellow-feather broilers with similar weight were randomly arranged in a 2  ×  2 factorial design with 2 kinds of compound trace element sources (inorganic [I] and organic [O] trace element supplemented with 80, 8, 60, 40, 0.15 mg/kg of Fe, Cu, Mn, Zn, and Se, respectively) and 2 levels of enzyme preparations (0 and 200 mg/kg). The 4 groups named I, O, IE, and OE with 6 replicates and 20 birds per replicate. The trail lasted for 28 days. Results showed that the average weight (ABW), average daily gain (ADG) of broilers in IE and OE groups significantly increased while the F/G significantly decreased as compared with group I and O (P < 0.05). Enzyme preparation supplementation, regardless of the trace element sources, significantly increased the duodenal and jejunal endogenous enzyme (e.g., Try and AACT) activity, and improved the morphology and jejunal barrier function evidenced by the increased villus height and MUC-2 mRNA expression (P < 0.05). Sequencing data manifested that enzyme preparations favorably modulated the cecal microflora by increasing bacterial diversity and abundance of short-chain fatty acid (SCFA)-producing bacteria (e.g., Anaerostipes, Anaerofusis, and Pygmaioactor), while decreasing the abundance of harmful bacteria (e.g., Desulfovibrio). Factorial analysis indicated that there were no interactions between enzyme preparation and trace element sources on growth performance and intestinal health of broiler chicks. In conclusion, dietary supplementation with enzyme preparations, regardless of the trace element sources, could enhance endogenous enzyme activity, improve intestinal morphology and barrier functions, and favorably modulate the cecal microflora, thereby improving the intestinal health and growth performance of broiler chicks.

The effects of exogenous xylanase supplementation on the in vivo generation of xylooligosaccharides and monosaccharides in broilers fed a wheat-based diet

1. This study quantified xylanase-induced changes in soluble monosaccharides, xylooligosaccharides (XOS) and volatile fatty acid (VFA) contents of the different sections of the gastrointestinal tract (GIT) and whether these were related to altered bird performance. 2. An in vitro digestion of the wheat-based diet was carried out with the xylanase (Econase XT at 16,000BXU/kg diet) to compare the in vitro and in vivo generation of these XOS and monosaccharides. For the in vivo study, 80 male Ross 508 b roiler chicks were split into two groups fed a wheat-based diet with or without Econase XT (16,000BXU/kg diet) for 21 days. 3. There were no effects of Econase XT inclusion on growth performance characteristics, likely a result of the high-quality wheat diet, the corresponding high performance of the control group (FCR average of 1.45 in controls) and the relatively young age of the birds (from four to 26 days of age). 4. Econase XT supplementation increased the xylotetraose (X₄) content in the colon (P = 0.046, enzyme x GIT section interaction) and the xylose contents in the colon and caeca (P < 0.001, enzyme x GIT section interaction). 5. The trend for increased acetate production in the caeca of Econase XT treated birds (P = 0.062) suggested that the XOS generated were subsequently fermented in the caeca, potentially impacting upon the types of microbiota present. 6. The present study suggested that wheat arabinoxylan degradation was enhanced by xylanase supplementation, which may have increased the production of beneficial volatile fatty acids (VFA) in the caeca, and thereby potentially modulated the caecal microbiome, but without affecting bird performance at this early age.

Xylo-oligosaccharides display a prebiotic activity when used to supplement wheat or corn-based diets for broilers

It is now well established that exogenous β-1,4-xylanases improve the nutritive value of wheat-based diets for poultry. Among other factors, the mechanism of action of exogenous enzymes may involve a microbial route resulting from the generation of prebiotic xylo-oligosaccharides (XOS) in the birds' gastro-intestinal (GI) tract. In a series of three experiments, the effect of XOS on the performance of broilers fed wheat or corn-based diets was investigated. In experiment 1, birds receiving diets supplemented with XOS displayed an increased weight gain (P = 0.08). The capacity of XOS to improve the performance of animals during a longer trial (42 d) was investigated (Experiment 2). The data revealed that diet supplementation with XOS, tested at two incorporation rates (0.1 and 1 g/kg), or with an exogenous β-1,4-xylanase resulted in an increased nutritive value of the wheat-based diet. An improvement in animal performance was accompanied by a shift in the microbial populations colonizing the upper portions of the GI tract. XOS were also able to improve the performance of broilers fed a corn-based diet, although the effects were not apparent at incorporation rates of 10 g/kg. Together these studies suggest that in some cases the capacity of β-1,4-xylanases to improve the nutritive value of wheat-based diets is more related to their ability to produce prebiotic XOS than to their ability to degrade arabinoxylans. The extremely low quantities of XOS used in this study also challenge the depiction of a prebiotic being a quantitatively fermented substrate. These data also bring into question the validity of the "cell wall" mechanism, as XOS elicited an effect with clearly no action on endosperm cell wall integrity and yet the performance effects noted were equivalent or superior to the added enzymes.