EFFECTS OF MICROALGAE, WITH OR WITHOUT XYLANASE SUPPLEMENTATION, ON GROWTH PERFORMANCE AND GUT HEALTH PARAMETERS OF BROILER CHICKENS
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2023
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Modern broilers are selected for a fast growth rate in a shorter period. The rapid increase in body weight leads to the possibility of gut disorders like poor gastrointestinal tract development, poor nutrient utilization, and gut dysbiosis if not managed properly. Nutritional programming using several feedstuffs and co-products has been studied to manage gut health without compromising growth performance. Microalgae are becoming potential sustainable feed ingredients, while terrestrial feedstuffs are becoming scarce and costly. They are rich in nutritional and functional values but have lower digestibility. Therefore, the study evaluated the effects of microalgae with or without xylanase supplementation on growth performance and gut health parameters of broiler chickens. A total of 162-day-old Cobb 500 chicks were raised for 35 days. Birds were fed with three dietary treatments: a) corn-soybean meal-based diet (CON), b) CON + 3% microalgae (MAG), and c) MAG + xylanase (MAG+XYN) in two phases (starter: d0-21 and finisher: d22-35). Weekly body weight (BW) and feed intake were recorded to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR). On d35, carcass and organ weight were recorded. Tissue samples were collected for histomorphology (duodenum, jejunum, and ileum) and total RNA isolation (ileum) on d3 and d35. In addition, blood was collected for serum immunoglobulin (on d35) and cecal digest for short-chain fatty acids, microbiota characterization, and functional metabolic pathways determination (on d3 and d35). Ileal gene expression related to the gut barrier, immunity, antioxidant, and nutrient transporter was determined using qPCR. Bioinformatics analyses were performed in CLC Genomic Workbench and STAMP. All other data were analyzed in GraphPad Prism or RStudio using one-way ANOVA followed by Tukey’s multiple comparison test. The significance level was set at p<0.05, and the results are expressed as the mean ± SEM.
The BW, ADG, and ADFI were significantly higher (p<0.05) in MAG and MAG+XYN compared to the CON group. No significant difference (p>0.05) was found for FCR. Relative carcass and organ weight also showed no significant differences among treatments (p>0.05). The expressions of ZO1, CD56, and SLC7A7 were significantly higher (p<0.05) in the MAG group. Statistically insignificant, however, villi height (VH), crypt depth (CD), VH:CD, and villi surface area (VSA) tended to increase in MAG and MAG+XYN groups both on d3 and d35. Relative microbial abundance at the genus level showed that MAG and MAG+XYN groups had a diverse microbial community on d3 and d35. However, no bacterial genus has a significant difference in their relative abundance on d3, but sixteen genera showed significant differences in their relative abundance among the dietary treatments on d35. Most of these bacteria are short-chain fatty acid-producing bacteria. Moreover, MAG and MAG+XYN-fed broilers had better responses than CON groups for metabolic pathways (D-mannose degradation, Pectin degradation I and II, β-1-4-mannan degradation, tetrahydrofolate biosynthesis, glutathione biosynthesis, glutathione-peroxide redox reactions, lactate fermentation to propanoate, acetate, and hydrogen, etc.) both on d3 and d35.
In conclusion, the use of microalgae with or without xylanase in a corn-soybean meal-based broilers diet promotes growth performance, immunity, and gut health of broiler chickens. Improvement in SCFA production, microbial diversity, and metabolic pathways is a sign of improved gut health. Most of the statistically changed pathways are related to fiber utilization and oxidative stress reduction. In addition, using microalgae in feeding programs may help to produce healthy broilers.
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Animal sciences, Nutrition, Arthrospira platensis, Growth performance, Gut health, Gut microbiota, Poultry, Xylanase
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116 pages
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