“Gut health” refers to the physical state and physiological function of the gastrointestinal tract and in the livestock system; this topic is often focused on the complex interacting components of the intestinal system that influence animal growth performance and host-microbial homeostasis. Regardless, there is an increasing need to better understand the complexity of the intestinal system and the various factors that influence gut health, since the intestine is the largest immune and neuroendocrine organ that interacts with the most complex microbiome population. As we face the post-antibiotic growth promoters (AGP) era in many countries of the world, livestock need more options to deal with food security, food safety, and antibiotic resilience to maintain agricultural sustainability to feed the increasing human population. Furthermore, developing novel antibiotic alternative strategies needs a comprehensive understanding of how this complex system maintains homeostasis as we face unpredictable changes in external factors like antibiotic-resistant microbes, farming practices, climate changes, and consumers’ preferences for food. In this review, we attempt to assemble and summarize all the relevant information on chicken gut health to provide deeper insights into various aspects of gut health. Due to the broad and complex nature of the concept of “gut health”, we have highlighted the most pertinent factors related to the field performance of broiler chickens.

Background: Coccidiosis is a poultry disease that occurs worldwide and is caused by Eimeria species. The infection is associated with reduced feed efficiency, body weight gain, and egg production. This study aimed to investigate the current status of coccidiosis and anticoccidial resistance to anticoccidial drugs used as part of control strategies for this disease in Korean chicken farms. Results: An overall prevalence of 75% (291/388) was found. Positive farms contained several Eimeria species (mean = 4.2). Of the positive samples, E. acervulina (98.6%), E. maxima (84.8%), and E. tenella (82.8%) were the most prevalent species. Compared with cage-fed chickens, broilers and native chickens reared in free-range management were more at risk of acquiring an Eimeria infection. Sensitivities to six anticoccidial drugs (clopidol, diclazuril, maduramycin, monensin, salinomycin, and toltrazuril) were tested using nine field samples. Compared with untreated healthy control chickens, the body weight gains of infected chickens and treated/infected chickens were significantly reduced in all groups. Fecal oocyst shedding was significantly reduced in four clopidol-treated/infected groups, three diclazuril-treated/infected groups, two toltrazuril-treated/infected groups, one monensin-treated/infected group, and one salinomycin-treated/infected group, compared with the respective untreated/infected control groups. Intestinal lesion scores were also reduced in three clopidol-treated/infected groups, one monensin-treated/infected group, and one toltrazuril-treated/infected group. However, an overall assessment using the anticoccidial index, percent optimum anticoccidial activity, relative oocyst production, and reduced lesion score index found that all field samples had strong resistance to all tested anticoccidial drugs. Conclusion: The results of this large-scale epidemiological investigation and anticoccidial sensitivity testing showed a high prevalence of coccidiosis and the presence of severe drug resistant Eimeria species in the field. These findings will be useful for optimizing the control of coccidiosis in the poultry industry.

African swine fever (ASF), a highly contagious disease of swine, has posed a significant global threat to the swine industry. As an archipelago, the Philippines has a geographic advantage when it comes to the risk of ASF transmission. However, since its introduction to the Philippines in 2019, it has proliferated not only in backyard and commercial farms but also in wild pig populations. While certain parts of the country were more affected than others, the epidemiologic features of ASF necessitate that all affected areas must be closely monitored and that confirmed cases be treated with the utmost care. With the very limited data on ASF epidemiology and surveillance in the Philippines, future efforts to combat ASF must place even greater emphasis on improved prevention and control strategies. It is worth mentioning that the government’s efforts toward comprehensive ASF surveillance and epidemiological investigation into the possible ASFV sources or transmission pathways are the most important measures in the prevention and control of ASF outbreaks. This review article provides a comprehensive overview of the current swine industry and ASF situation in the Philippines, which includes its epidemiology, surveillance, prevention, and control strategies.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition caused by the disruption of the intestinal barrier. The intestinal barrier is maintained by tight junctions (TJs), which sustain intestinal homeostasis and prevent pathogens from entering the microbiome and mucosal tissues. Ziziphus jujuba Miller (Z. jujuba) is a natural substance that has been used in traditional medicine as a therapy for a variety of diseases. However, in IBD, the efficacy of Z. jujuba is unknown. Therefore, we evaluated ZJB in Caco2 cells and a dextran sodium sulfate (DSS)-induced mouse model to demonstrate its efficacy in IBD. Z. jujuba extracts were prepared using 70% ethanol and were named ZJB. ZJB was found to be non-cytotoxic and to have excellent antioxidant effects. We confirmed its anti-inflammatory properties via the down-regulation of inflammatory factors, including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). To evaluate the effects of ZJB on intestinal barrier function and TJ improvement, the trans-epithelial electrical resistance (TEER) and fluorescein isothiocyanate-dextran 4 kDa (FITC-Dextran 4) permeability were assessed. The TEER value increased by 61.389% and permeability decreased by 27.348% in the 200 μg/mL ZJB group compared with the 50 ng/mL IL-6 group after 24 h. Additionally, ZJB alleviated body weight loss, reduced the disease activity index (DAI) score, and induced colon shortening in 5% DSS-induced mice; inflammatory cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 were down-regulated in the serum. TJ proteins, such as Zonula occludens (ZO)-1 and occludin, were up-regulated by ZJB in an impaired Caco2 mouse model. Additionally, according to the liquid chromatography results, in tandem with mass spectrometry (LC-MS/MS) analysis, seven active ingredients were detected in ZJB. In conclusion, ZJB down-regulated inflammatory factors, protected intestinal barrier function, and increased TJ proteins. It is thus a safe, natural substance with the potential to be used as a therapeutic agent in IBD treatment.

Avian coccidiosis is a disease caused by members of the genus Eimeria. Huge economic losses incurred by the global poultry industry due to coccidiosis have increased the need for cost-effective and easily available recombinant vaccines. Microneme protein 2 (MIC2) and surface antigen 1 (SAG1) of E. tenella have been recognised as potential vaccine candidates. However, the genetic diversity of the antigens in field isolates, which affects vaccine efficacy, has yet to be largely investigated. Here, we analysed genetic diversity and natural selection of etmic2 and etsag1 in Korean E. tenella isolates. Both genes exhibited low levels of genetic diversity in Korean isolates. However, the two genes showed different patterns of nucleotide diversity and amino acid polymorphism involving the E. tenella isolates obtained from different countries including China and India. These results underscore the need to investigate the genetic diversity of the vaccine candidate antigens and warrant monitoring of genetic heterogeneity and evolutionary aspects of the genes in larger numbers of E. tenella field isolates from different geographical areas to design effective coccidial vaccines.