The effect of subtilisin-like serine protease Bacillus pumilus and histidine acid 3-phytase Pantoea brenneri on growth performance, digestibility, immune organs, and expression of intestinal barrier genes in broiler chickens

Authors: Daria Pudova, Danil Kovalenko, Marat Lutfullin, Guzel Lutfullina and Margarita Sharipova

Ger. J. Vet. Res 2025. vol. 5, Iss. 1 pp:40-52
Doi: https://doi.org/10.51585/gjvr.2025.1.0118

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Abstract:

The study determined the effect of subtilisin-like protease Bacillus pumilus and phytase Pantoea brenneri on poultry growth performance, digestibility, digestion of feed nutrients, changes in immune organs weight, as well as on differential gene expression in the ileum tissues of broilers. A total of 240 Ross 308 broilers were divided into four groups: one control and three experimental groups. Each group contained 60 birds, organized into four replicates of 15 birds each. Groups received four feed rations from 0 to 35 days. The diet of the control group was a basal diet (BD) without additives. In the experimental groups, the BD was supplemented with one of the additives: protease (10 U/kg), phytase (1000 FTU/kg), or their combination. The results showed that decreasing the addition of phytase and protease to feed increased body weight and average daily gain of broilers (p<0.05) while reducing the feed conversion ratio (p<0.0001). Enzyme supplementation increased calcium, phosphorus, and nitrogen availability and improved protein, fiber, and fat digestibility (p<0.002). No significant differences were found in the weight of the liver, spleen, thymus, and bursa of Fabricius in the experimental and control groups (p>0.05). The gene expression of pro-inflammatory cytokines on day 14 of feeding was lower in the groups receiving protease and phytase compared to the control group (p<0.0001). In the case of MUC2 and Occludin genes, increased expression was observed in the group receiving protease (p<0.05). In contrast, decreased expression was observed for the groups receiving phytase and combined feed additive. Junctional adhesion molecule-2 (JAM2) gene expression decreased for all experimental groups receiving enzyme feed additives (p<0.05). Thus, it was established that adding protease and phytase to the BD for broilers enhances the digestibility of feed components, reduces the amount of feed consumed, doesn't affect the weight of liver and lymphoid organs, and reduces inflammation in the ileum of chickens. At the same time, protease supplementation increases the mucin and tight contact protein gene expression, which may indicate an improvement in the ileum of broiler chickens.

Keywords:

Protease, Phytase, Poultry, Feed additive, Intestinal barrier genes, Immune response

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