The gut microbiota is a complex ecological community and widely recognized in many aspects of research, but little is known on the relation between gut microbiota and embryonic development in chickens. The aim of this study was to explore the dynamic distribution of gut microbiota in chickens' embryos during stages of developments (chicken embryos that had incubated until day 3 [E3], day 12 [E12], and day 19 [E19]). Here, 16S rRNA gene sequencing was performed on the gut microbiota in chicken embryos across different developmental stages. Twenty-one phyla and 601 genera were present in chicken embryos, and 96 genera such as Ochrobactrum , Phyllobacterium, and Amycolatopsis were the core microbiota in the 3 stages of development. Second, 94 genera of microbes were found to change significantly between E3 and E12, and 143 genera significantly differed between E12 and E19 in chicken embryos ( P < 0.05). Ochrobactrum and Amycolatopsis decreased with growth changes: E3 (30.4%), E12 (25.1%), and E19 (13.6%) and E3 (11.5%), E12 (7.4%), and E19 (5.6%), respectively. Contrarily, Phyllobacterium increased to 47.9% at E19, indicating the growing trend of microbial diversity among the embryos' development. Moreover, the principal component analysis showed a high level of similarities between E3 and E12 compared with E19, whereas the alpha analysis showed more diversity of gut microbiota at E19. Furthermore, the functional predictions showed that metabolic pathways such as energy metabolism and genetic information processing were significantly enriched on day 3 and day 12 in our study, suggesting their strong influence on growth, development, and immunity of chicken embryos. Our findings provide insights into the understanding of dynamic shifts of gut microbiota during chicken embryonic growth.

The common pheasant Phasianus colchicus, belonging to the order Galliformes and family Phasianidae, is the most widespread species. Despite a long history of captivity, the domestication of this bird is still at a preliminary stage. Recently, the demand for accelerating its transformation to poultry for meat and egg production has been increasing. In this study, we assembled high quality, chromosome scale genome of the common pheasant by using PacBio long reads, next‐generation short reads, and Hi‐C technology. The primary assembly has contig N50 size of 1.33 Mb and scaffold N50 size of 59.46 Mb, with a total size of 0.99 Gb, resolving most macrochromosomes into single scaffolds. A total of 23,058 genes and 10.71 Mb interspersed repeats were identified, constituting 30.31% and 10.71% of the common pheasant genome, respectively. Our phylogenetic analysis revealed that the common pheasant shared common ancestors with turkey about 24.7–34.5 million years ago (Ma). Rapidly evolved gene families, as well as branch‐specific positively selected genes, indicate that calcium‐related genes are potentially related to the adaptive and evolutionary change of the common pheasant. Interestingly, we found that the common pheasant has a unique major histocompatibility complex B locus (MHC‐B) structure: three major inversions occurred in the sequence compared with chicken MHC‐B. Furthermore, we detected signals of selection in five breeds of domestic common pheasant, several of which are production‐oriented.

Environmental stressors can promote the vulnerability of animals to infections; it is therefore, essential to understand how stressors affect the immune system, the adaptive capacity of animals to respond, and effective techniques in managing stress. This review highlights scientific evidence regarding environmental stress challenge models and the potential effectiveness of vitamin supplementation. The major environmental stressors discussed are heat and cold stress, feed restriction, stocking density, and pollutants. Much work has been done to identify the effects of environmental stress in broilers and layers, while few involved other types of poultry. Studies indicated that chickens' performance, health, and welfare are compromised when challenged with environmental stress. These stressors result in physiological alterations, behavioral changes, decreased egg and meat quality, tissue and intestinal damage, and high mortalities. The application of vitamins with other nutritional approaches can help in combating these environmental stressors in chickens. Poultry birds do not synthesize sufficient vitamins during stressful periods. It is therefore suggested that chicken diets are supplemented with vitamins when subjected to environmental stress. Combination of vitamins are considered more efficient than the use of individual vitamins in alleviating environmental stress in chickens.

High-energy-density diet could increase body weight at the expense of the intestinal health of the animals. In order to optimize production without negatively influencing the gut health of chickens, dietary supplementation with bacitracin methylene disalicylate (BMD) is a common feeding strategy adopted to enhance production performance and intestinal health. Studies have suggested that BMD could improve chicken growth performance and gut health through modulation of the gut microbiota. The current study investigated the effect of BMD supplementation in a normal-energy (NE) or high-energy (HE) diet on growth performance, organ weights, jejunal morphology, and gut microbiota of broiler chickens at different growth stages. Birds were allocated to four treatments: normal-energy basal diet (NE-BAS), normal-energy BMD diet (NE-BMD), high-energy basal diet (HE-BAS), and high-energy BMD diet (HE-BMD). In the starter phase, body weight and body weight gain were reduced significantly (p < 0.05) in chickens fed HE diets compared to those fed NE diets. The FCR was significantly higher (p < 0.05) in birds fed HE-BMD diets in the starter phase but lower (p < 0.05) during the grower phase when compared to other treatments. Moreover, the relative bursa weight increased significantly (p = 0.0220) among birds that received HE diets. Birds fed HE-BMD had greater villus height (p = 0.054) than NE-BMD group. Among the chickens fed the HE diets, those that received BMD treatment had a significantly increased (p = 0.003) villus width (13.3% increase) compared to those that received the basal diet. Improved population of Firmicutes was observed in chickens fed HE-BMD diet when compared to HE-BAS. Our results imply that BMD may be more effective in improving intestinal health when supplemented in a high-energy diet for broiler chickens.

Pullorum disease is one of the most common diarrhea-related diseases caused by Salmonella enterica subspecies enterica serovar Gallinarum biovar Pullorum (S. Pullorum); it negatively affects the poultry industry. However, limited studies have explored the association between the gut microbiota and S. Pullorum infection in chickens. In the present study, we performed a microbiome comparison and a microbiome genome-wide association study (mGWAS) to investigate the association among the host genetics, the gut microbiota, and pullorum disease in chickens. We found that S. Pullorum infection in chickens could alter the abundance of 39 bacterial genera (P < 0.05). The altered structure and composition of the gut microbiota were also detected in the offspring. mGWAS results revealed host genetic variants to be prominently associated with gut microbial diversity and individual microbes. The pathogens Pelomonas and Brevundimonas, which had a high abundance in positive parent chickens and their offspring, were significantly associated with several genetic mutations in immunity-related genes, such as TGIF1, TTLL12, and CCR7. This finding explained why Pelomonas and Brevundimonas were heritable in S. Pullorum-infected chickens. The heritable gut microbes and identified genetic variants could provide references for the selection of resistant chickens and the elimination of pullorum disease. IMPORTANCE The present study investigated the association among the host genome, the gut microbiome, and S. Pullorum infection in chickens. The results suggested that the gut microbial structure is altered in S. Pullorum-infected chickens. The diversity and abundance of the gut microbiota remarkably differed between the offspring coming from S. Pullorum-positive and S. Pullorum-negative chickens. Heritable gut microbiota were detected in the offspring. Moreover, host genetic variants were associated with microbial diversity and individual gut microbes. The pathogens Pelomonas and Brevundimonas, which exhibited a high heritability in S. Pullorum-positive parents and their offspring, were associated with several genetic mutations in immunity-related genes.