Xylanase and stimbiotic supplementation improve broilers performance and nutrient digestibility across both wheat-barley and corn-based diets

The present study investigated the effects of supplemental xylanase or stimbiotic in male broiler chickens fed either corn- or wheat-barley-based diets. A total of 1,296 Ross 308 day-old chicks were assigned to a 2 × 3 factorial design, evaluating the effects of diet grain source (wheat-barley or corn) and additives (none, xylanase, or stimbiotic). The stimbiotic used in the present study contained xylanase and fermentable xylo-oligosaccharides. Each treatment was replicated 8 times, with 27 birds per replicate pen. At day 21, 3 birds per pen were selected for blood sample collection and another 3 birds at day 27 for digesta collection. The final body weight at day 42 was not statistically affected by grain source, additive supplementation, or their interaction (P > 0.05). Over the entire production period (0-42 d), an interaction between grain source and additive supplementation was found for feed conversion ratio (FCR), where xylanase or stimbiotic improved the FCR across the diet type, with a more pronounced improvement achieved when supplemented to the wheat-barley based diets (P < 0.01). A feed grain × additive interaction resulted in lower total feed intake in birds fed the wheat-barley based diets only in response to stimbiotic (P < 0.05). Ileal viscosity was also affected by an interaction between grain source and additive supplementation, in which viscosity reduction by xylanase or stimbiotic was only achieved in birds fed the wheat-barley based diets (P < 0.01). Similarly, an interaction was found in the ileal digestibility coefficient of protein (P = 0.016) and starch (P = 0.006), where either xylanase or stimbiotic improved the digestibility only in birds offered the wheat-barley based diets. Serum fluorescein isothiocyanate dextran level was higher in birds fed the corn-based diets compared to those fed the wheat-barley based diets (P < 0.01). These results suggest that dietary supplementation with either xylanase or stimbiotic improved feed efficiency, regardless of the dietary grain source, likely through enhanced nutrient digestibility and/or reduced digesta viscosity.