cThis study focused on identifying reproducible effects of dietary supplementation with a mannan oligosaccharide (MOS) on the broiler cecal bacterial community structure and function in a commercial production setting. Two separate trials, each with a control and a supplemented group, were carried out in the same commercial location and run concurrently. Approximately 10,000 birds from the same commercial hatchery were mirror imaged into each of four commercial broiler sheds and fed either a control or supplemented diet. Cecal contents were obtained on days 7, 21, and 35 posthatch from 12 randomly caught broilers from each group. Bacterial pyrosequencing was performed on all samples, with approximately 250,000 sequences obtained per treatment per time point. The predominant phyla identified at all three time points in both trials were Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, and Tenericutes, representing >99% of all sequences. MOS supplementation altered the bacterial community composition from 7 days supplementation through 35 days supplementation. Bacteroidetes appeared to be replacing Firmicutes as a result of supplementation, with the most noticeable effects after 35 days. The effects of supplementation were reproducible across both trials. PICRUSt was used to identify differences between the functional potentials of the bacterial communities as a result of MOS supplementation. Using level 3 KEGG ortholog function predictions, differences between control and supplemented groups were observed, with very strong segregation noted on day 35 posthatch in both trials. This indicated that alterations of bacterial communities as a result of MOS are likely to alter the functional capability of the cecum.
The gastrointestinal microbiota plays a vital role in nutritional, physiological, and protective functions in animals (1). An understanding and a description of the intestinal microbial communities in broilers are important for the development of new feed additives and the appropriate manipulation of diets to improve broiler performance, health, and welfare (2). The intestinal microbiota has a major impact on the bioavailability and bioactivity of dietary components by consuming, storing, and circulating nutrients effectively, while also impacting the host's ability to resist infection, thereby making an essential contribution to host health and performance (3). Poor intestinal health in poultry is associated with increased susceptibility to infectious disease and colonization by pathogens (4). Bacterial-disease outbreaks impose significant constraints on poultry production, adversely impacting the poultry industry by reducing animal welfare and productivity through disease, poor digestion, and poor nutrient absorption. This, in turn, can lead to significant losses for the farmer and can increase the potential for the contamination of poultry products marketed for human consumption (5).Traditionally, antibiotics have been used in poultry feed at subtherapeutic levels to prevent clinical and subclini...