The gut of warm-blooded animals is colonized by microbes possibly constituting at least 100 times more genetic material of microbial cells than that of the somatic cells of the host. These microbes have a profound effect on several physiological functions ranging from energy metabolism to the immune response of the host, particularly those associated with the gut immune system. The gut of a newly hatched chick is typically sterile but is rapidly colonized by microbes in the environment, undergoing cycles of development. Several factors such as diet, region of the gastrointestinal tract, housing, environment, and genetics can influence the microbial composition of an individual bird and can confer a distinctive microbiome signature to the individual bird. The microbial composition can be modified by the supplementation of probiotics, prebiotics, or synbiotics. Supplementing these additives can prevent dysbiosis caused by stress factors such as infection, heat stress, and toxins that cause dysbiosis. The mechanism of action and beneficial effects of probiotics vary depending on the strains used. However, it is difficult to establish a relationship between the gut microbiome and host health and productivity due to high variability between flocks due to environmental, nutritional, and host factors. This review compiles information on the gut microbiota, dysbiosis, and additives such as probiotics, postbiotics, prebiotics, and synbiotics, which are capable of modifying gut microbiota and elaborates on the interaction of these additives with chicken gut commensals, immune system, and their consequent effects on health and productivity. Factors to be considered and the unexplored potential of genetic engineering of poultry probiotics in addressing public health concerns and zoonosis associated with the poultry industry are discussed.

Point-of-care analyzers such as the Vetscan VS2 (VS2) that provide fast results are becoming an important tool in a variety of clinical and research settings. Several studies have explored the use of the VS2 to evaluate blood chemistry values in chickens; however, the VS2 analyzer has not yet been tested in turkeys. The first objective of this study was to utilize the VS2 to evaluate possible time-dependent changes in biochemical blood analytes over time, such as glucose, calcium, or sodium. Blood samples from 30 turkeys were analyzed with the VS2 at three time points (0, 15–20, and 40–60 min post collection), and it was found that the blood biochemistry values were stable when stored at 4 °C and analyzed within 60 min of collection. Next, we assessed the agreement between the VS2 portable analyzer and the reference benchtop analyzer (Cobas c501) and found that all of the blood analytes were comparable between both analyzers. Finally, we determined reference intervals using 120 blood samples collected from turkeys in the brooding period (0–7 days) and 118 samples collected from turkeys in the growing period (1–12 weeks). Although the values were compared to the published data, the understanding of any observed differences was challenging because reference intervals for the biochemical values in turkeys are limited, and the origin of these interval values could not be traced. Significant differences in the whole blood analytes were noted between brooding and growing birds. This study offers reassurance of the validity of the use of portable analyzers in the field for turkey veterinarians. We conclude that the VS2 can be used to measure biochemical analytes in turkeys and provide the first reference intervals for brooding and growing turkeys using this instrument.