ENVIRONMENT, HEALTH, AND BEHAVIOR Composition of Microbiota in Content and Mucus from Cecae of Broiler Chickens as Measured by Fluorescent In Situ Hybridization with Group-Specific, 16S rRNA-Targeted Oligonucleotide Probes1

Six group-specific 16S rRNA-targeted oli- gonucleotide probes were used to investigate the compo- sition of the microbiota of cecal content and mucus from broiler chickens. Together, the probes hybridized to as many as 94.7% of the bacteria detectable with the univer- sal probe Bact338 in the content of the cecum of 2-d-old chicks. Fewer bacteria gave signals with these probes as the birds aged, and coverage was as low as 76% for the bacteria in cecal content of a 6-wk-old chicken. In the cecal content of 2-d-old chicks, approximately 56, 34, and 3% of the bacteria detectable with the universal probe reacted with the probes Enter1432 (enterics), Lacto722 (Lactobacillus/Streptococcus/Enterococcus), and Bif164 (bi-