Percent G+C profiling accurately reveals diet-related differences in the gastrointestinal microbial community of broiler chickens

Broiler chickens from eight commercial farms in Southern Finland were analy zed for the structure of their gastrointestinal microbial community by a no nselective DNA-based method, percent G+C-based profiling. The bacteriologic al impact of the feed source and in-farm whole-wheat amendment of the diet was assessed by percent G+C profiling. Also, a phylogenetic 16S rRNA gene ( rDNA)-based study was carried out to aid in interpretation of the percent G +C profiles. This survey showed that most of the 16S rDNA sequences found c ould not be assigned to any previously known bacterial genus or they repres ented an unknown species of one of the taxonomically heterogeneous genera, such as Ruminococcus or Clostridium. The data from bacterial community prof iling were analyzed by t-test, multiple linear regression, and principal-co mponent statistical approaches. The percent G+C profiling method with appro priate statistical analyses detected microbial community differences smalle r than 10% within each 5% increment of the percent G+C profiles, Diet turne d out to be the strongest determinant of the cecal bacterial community stru cture. Both the source of feed and local feed amendment changed the bacteri ological profile significantly, whereas profiles of individual farms with i dentical feed regimens hardly differed from each other. This suggests that the management of typical Finnish farms is relatively uniform or that hygie ne on the farm, in fact, has little impact on the structure of the cecal ba cterial community. Therefore, feed compounders should have a significant ro le in the modulation of gut microflora and consequently in prevention of ga strointestinal disorders in farm animals.