Heat stress has emerged as a serious threat to the global poultry industry due to climate change. Heat stress can negatively impact the growth, gut health, immune function, and production and reproductive performances of poultry. Different strategies have been explored to mitigate heat stress in poultry; however, only a few have shown potential. Probiotics are gaining the attention of poultry nutritionists, as they are capable of improving the physiology, gut health, and immune system of poultry under heat stress. Therefore, application of probiotics along with proper management are considered to potentially help negate some of the negative impacts of heat stress on poultry. This review presents scientific insight into the impact of heat stress on poultry health and growth performance as well as the application of probiotics as a promising approach to alleviate the negative effects of heat stress in poultry.

This study investigated the effects of Bacillus licheniformis-fermented products on the growth performance and fecal microbial community of broilers. A total of 144 one-day-old male broiler chicks (Ross 308) were randomly assigned into 4 dietary treatments, with 6 replicate cages per treatment and 6 birds per cage. The dietary treatments comprised a basal diet as control, control plus 1 and 3 g/kg of B. licheniformis-fermented products, and control plus 10 mg/kg of enramycin. The results indicated that 3 g/kg of B. licheniformis-fermented products increased (P < 0.05) the BW and ADG of broilers relative to controls. No significant difference was observed in the growth performance of broilers fed enramycin and 3 g/kg of B. licheniformis-fermented products. However, principal coordinate analysis and a heatmap of species abundance indicated distinct clusters between the groups treated with enramycin and 3 g/kg of B. licheniformis-fermented products. The abundance of the phylum Firmicutes in feces increased (P < 0.05) in broilers fed 3 g/kg of B. licheniformis-fermented products, whereas the abundance of the phyla Verrucomicrobia and Bacteroidetes in feces decreased (P < 0.05) in response to treatment with 3 g/kg of B. licheniformis-fermented products. The abundance of the genera Enterococcus, Akkermansia, Ruminococcus torques group, Faecalibacterium, and Parabacteroides in feces decreased (P < 0.05) in broilers fed 3 g/kg of B. licheniformis-fermented products, whereas the abundance of the genus Lactobacillus in feces increased (P < 0.05) in response to treatment with 3 g/kg of B. licheniformis-fermented products. The average abundance of the genus Lactobacillus in feces was positively correlated with the growth performance of broilers. These results demonstrate that B. licheniformis-fermented products can improve the growth performance and fecal microflora composition of broilers.

Taiwanese green propolis is a prenylated flavonoid rich honeybee product and propolins isolated from Taiwanese green propolis exert a broad spectrum of biological activities, such as anti-cancer and anti-oxidant. However, the anti-bacterial effects of Taiwanese green propolis or propolins are still poorly understood. In the current study, the antibacterial effects of Taiwanese green propolis and propolins were evaluated. Results show that the maximum dry matter yields of Taiwanese green propolis were observed in the 95% and 99.5% ethanol extracts compared to other extraction methods. Consistently, the highest concentration of propolins C, D, F and G from Taiwanese green propolis was obtained in 95% and 99.5% ethanol extracts. Propolins inhibited the growth of gram-positive bacterial strains (Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes and Paenibacillus larvae). The average minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of propolins from ethanol extracts were 20 μg/ml. Among the propolins, propolin C had the highest antibacterial activity. Furthermore, Taiwanese green propolis also showed antibacterial activity against methicillin-resistant S. aureus (MRSA). In conclusion, these results demonstrate that Taiwanese green propolis and propolins have significant antibacterial activity, particularly against gram-positive bacterial strains.

Elevated oxidative stress is closely associated with obesity. Emerging evidence shows that instead of being a consequence of obesity, oxidative stress may also contribute to fat formation. Nonselenocysteine‐containing phospholipid hydroperoxide glutathione peroxidase (NPGPx) is a conserved oxidative stress sensor/transducer and deficiency of NPGPx causes accumulation of reactive oxygen species (ROS). In this communication, we show that NPGPx was highly expressed in preadipocytes of adipose tissue. Deficiency of NPGPx promoted preadipocytes to differentiate to adipocytes via ROS‐dependent dimerization of protein kinase A regulatory subunits and activation of CCAAT/enhancer‐binding protein beta (C/EBPβ). This enhanced adipogenesis was alleviated by antioxidant N ‐acetylcysteine (NAC). Consistently, NPGPx‐deficient mice exhibited markedly increased fat mass and adipocyte hypertrophy, while treatment with NAC ablated these phenotypes. Furthermore, single nucleotide polymorphisms (SNPs) in human NPGPx gene, which correlated with lower NPGPx expression level in adipose tissue, were associated with higher body mass index (BMI) in several independent human populations. These results indicate that NPGPx protects against fat accumulation in mice and human via modulating ROS, and highlight the importance of targeting redox homeostasis in obesity management.

Poultry coccidiosis is an intestinal infection caused by an intracellular parasitic protozoan of the genus Eimeria. Coccidia-induced gastrointestinal inflammation results in large economic losses, hence finding methods to decrease its prevalence is critical for industry participants and academic researchers. It has been demonstrated that coccidiosis can be effectively controlled and managed by employing anticoccidial chemical compounds. However, as a result of their extensive use, anticoccidial drug resistance in Eimeria species has raised concerns. Phytochemical/herbal medicines (Artemisia annua, Bidens pilosa, and garlic) seem to be a promising strategy for preventing coccidiosis, in accordance with the “anticoccidial chemical-free” standards. The impact of herbal supplements on poultry coccidiosis is based on the reduction of oocyst output by preventing the proliferation and growth of Eimeria species in chicken gastrointestinal tissues and lowering intestinal permeability via increased epithelial turnover. This review provides a thorough up-to-date assessment of the state of the art and technologies in the prevention and treatment of coccidiosis in chickens, including the most used phytochemical medications, their mode of action, and the applicable legal framework in the European Union.

Swine dysentery and necrotic enteritis are a bane to animal husbandry worldwide. Some countries have already banned the use of antibiotics as growth promoters in animal production. Surfactin is a potential alternative to antibiotics and antibacterial agents. However, the antibacterial activity of Bacillus species-derived surfactin on Brachyspira hyodysenteriae and Clostridium perfringens are still poorly understood. In the current study, the antibacterial effects of surfactin produced from Bacillus subtilis and Bacillus licheniformis on B. hyodysenteriae and C. perfringens were evaluated. Results showed that multiple surfactin isoforms were detected in B. subtilis, while only one surfactin isoform was detected in B. licheniformis fermented products. The surfactin produced from B. subtilis exhibited significant antibacterial activity against B. hyodysenteriae compared with surfactin produced from B. licheniformis. B. subtilis-derived surfactin could inhibit bacterial growth and disrupt the morphology of B. hyodysenteriae. Furthermore, the surfactin produced from B. subtilis have the highest activity against C. perfringens growth. In contrast, B. licheniformis fermented product-derived surfactin had a strong bacterial killing activity against C. perfringens compared with surfactin produced from B. subtilis. These results together suggest that Bacillus species-derived surfactin have potential for development as feed additives and use as a possible substitute for antibiotics to prevent B. hyodysenteriae and C. perfringens-associated disease in the animal industry.