Dietary Probiotics Modulate Gut Barrier and Immune-Related Gene Expression and Histomorphology in Broiler Chickens under Non- and Pathogen-Challenged Conditions: A Meta-Analysis

Abstract

Data published in the literature about the favorable effects of dietary probiotics on gut health in broiler chickens are inconsistent. To obtain a more comprehensive understanding, we conducted a meta-analysis to assess the effects of probiotics on the gut barrier and immune-related gene expression, histomorphology, and growth in chickens that were either challenged or non-challenged with pathogens. From the 54 articles published between 2012 and 2022, subsets of data, separately for non-challenged and challenged conditions, for response variables were created. The mean dietary probiotic concentrations ranged from 4.7 to 6.2 and 4.7 to 7.2 log10 colony-forming unit/kg under non-challenged and challenged conditions, respectively. Probiotics increased the expression of genes for mucins and tight junction proteins in the jejunum and ileum at weeks 3 and 6. The stimulatory effect of probiotics on tight junction protein expression was partly stronger in challenged than in non-challenged birds. Meta-regressions also showed an anti-inflammatory effect of probiotics under challenged conditions by modulating the expression of cytokines. Probiotics improved villus height at certain ages in the small intestine while not influencing growth performance. Dietary metabolizable energy, crude protein, and days post-infection modified the effects of probiotics on the observed variables. Overall, meta-regressions support the beneficial effects of probiotics on gut integrity and structure in chickens.

Nutraceuticals vs. antibiotic growth promoters: differential impacts on performance, meat quality, blood lipids, cecal microbiota, and organ histomorphology of broiler chicken

“…It has been suggested that the decrease in small intestine goblet cell density may be directly or indirectly because of the EO effect on the gut microbial population ( Du and Guo, 2021 ; Hosseinzadeh et al, 2023 ). Moreover, the current results are consistent with recent studies by Danladi et al (2022) and Yosi and Metzler-Zebeli (2023) concerning the effect of PRO on the gut microstructure and improved intestinal histomorphology. It is well known that dietary PRO potentially modulates gut microbiota, regularly benefiting the bird and that GIT can adjust and modify its microstructure in response to changing situations such as diet ( Danladi et al, 2022 ; Yosi and Metzler-Zebeli, 2023 ).…”

“…The demand for antibiotic-free additives is now being utilized, thus the search for natural additives as an alternative to AGP has augmented research on nutraceuticals. Among these alternatives, SP, CV, EO, and PRO have enormous potential benefits because they are natural products and are free of harmful constituents and chemicals ( El-Shall et al, 2023 ; Yosi and Metzler-Zebeli, 2023 ). Therefore, the main goal of the current trial was to determine the effect of SP+CV, REO, and PRO supplementation as alternatives to AGP on growth performance, blood biochemical constitutes, meat quality, cecal microbiota, and organ histomorphology of broilers.…”

“…Green and healthful nutraceuticals can fill this gap and be used in poultry production instead of antibiotics. In poultry, nutraceuticals can be more beneficial in promoting immunological responses, enhancing growth performance, and improving the quality of the final product ( Abd El-Hack et al, 2022 ; Yosi and Metzler-Zebeli, 2023 ).…”

“…Probiotics, live microbial products, are feed additives that play a beneficial role in maintaining the balance of gastrointestinal tract ( GIT ) microbiota ( Yosi and Metzler-Zebeli, 2023 ). This balance will improve digestion and absorption of nutrients, boost immune response, and enhance growth performance and antioxidant capacity, eventually resulting in better profitability ( Yosi and Metzler-Zebeli, 2023 ).…”

“…Probiotics, live microbial products, are feed additives that play a beneficial role in maintaining the balance of gastrointestinal tract ( GIT ) microbiota ( Yosi and Metzler-Zebeli, 2023 ). This balance will improve digestion and absorption of nutrients, boost immune response, and enhance growth performance and antioxidant capacity, eventually resulting in better profitability ( Yosi and Metzler-Zebeli, 2023 ). Probiotics perform their functions through various mechanisms, involving nutritional competition with harmful microbes, adhesion to the GIT surface, and production of anti-pathogenic substances ( Latif et al, 2023 ; Jha et al, 2020 ).…”