Pretreatment of surfactant Tween 80 and fibrolytic enzyme influencing volatile fatty acid and methane production of a total mixed ration by mixed rumen microorganisms at in vitro

Abstract

Abstract In vitro rumen dry matter degradability, volatile fatty acid (VFA) and methane production were examined in a total mixed ration pretreated with different levels of either commercial cellulolytic enzyme (CCE), the surfactant poly oxyethylene sorbitan monoolate (Tween 80) or both: (i) no pretreatment (Control); (ii) with 1% CCE alone; (iii) with 2% CCE alone; (iv) with 1% Tween 80 alone; (v) with 1% Tween 80 + 1% CCE;(vi) with 1% Tween 80 + 2% CCE; (vii) with 2% Tween 80 alone; (viii) with 2% Tween 80 + 1% CCE; and (ix) with 2% Tween 80 +2% CCE. In all culture supernatants of rumen microorganisms, activities of xylanase and cellulase were significantly (P < 0.001) increased with pretreatment of CCE alone, Tween 80 alone and both combined. Within the same treatment of no CCE and 1% CCE levels, the total VFA concentration was significantly (P < 0.001) higher with 2% Tween 80 than with no or 1% Tween 80 treatments. The molar percentage of propionate significantly (P < 0.001) increased only with Tween 80. Throughout the in vitro incubation, the average value of methane concentration decrease was greater (P < 0.001) with 1% CCE treatment than with no CCE and 2% CCE treatments, accounting for 0.797 and 0.887 of no CCE and 2% CCE treatments, respectively. Accumulative methane production was significantly lower with 1% CCE treatment than with no CCE and 2% CCE treatments. A ratio of VFA : methane production was significantly (P < 0.001) higher with 2% Tween 80 treatment than with no Tween 80 and 1% Tween 80 treatments, showing the average values of 7.28, 5.33 and 6.69, respectively.