Effects of Tween 80 pretreatment on dry matter disappearance of rice straw and cellulolytic bacterial adhesion

Abstract

An in situ experiment was conducted to find out whether Tween 80 improves rice straw digestion through increased adhesion of major fibrolytic bacteria. Rice straw was sprayed with various levels of Tween 80 non-ionic surfactant or SDS ionic surfactant 24 h before incubation in the rumen of Holstein steers. Dry matter (DM) disappearance and adhesion of F. succinogenes, R. flavefaciens and R. albus on rice straw after in situ incubation were measured by real-time PCR. Application of Tween 80 increased DM disappearance, which was more noticeable at an application level of 1% compared to lower application levels. Application of SDS resulted in an opposite response in DM disappearance with highest reduction in DM disappearance at 1% level. In a subsequent in situ experiment, higher Tween 80 was applied to rice straw in an attempt to find the optimum application level. Tween 80 at 2.5% gave better DM disappearance than 1% with a similar result at 5%. Therefore, an adhesion study was carried out using rice straw treated with 2.5% Tween 80. Our results indicated that Tween 80 reduced adhesion of all three major rumen fibrolytic bacteria to rice straw. Present data clearly show that improved DM disappearance by Tween 80 is not due to increased bacterial adhesion onto substrates.