The objective of the present study was to quantify the cellulolytic bacteria population using in vitro culture containing sodium hydroxide treated or untreated cottonseed hulls (CH) determined by real-time polymerase chain reaction (RT-PCR). Cottonseed hulls were used as untreated or chemical treated using NaOH as 20 g/kg DM [a solution of NaOH (20%) was sprayed on CH and kept for 48 h at room temprature]. Forty-five ml of medium was supplied into a 100 ml bottle that approximately containing 0.45 g of the feed sample (4 replicates). Each bottle was inoculated under carbon dioxide with 5 ml of isolated rumen bacteria. The bottles were incubated for 96 h at 38.6º C. After the incubation, 1 ml of each bottle was sampled for DNA extraction. Then, quantification of cellulolytic bacteria was carried out using RT-PCR. Bacterial rDNA concentrations were measured relative to total bacteria amplification (BBCt). Data were analyzed using the GLM procedure of SAS 9.1 and the means were compared by the Tukey test (P<0.05). Chemical treatment had no significant effect (P<0.05) on the quantity of cellulolytic bacteria using present in vitro experimental conditions.

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