Effect of exogenous fibrolytyc enzyme on in vitro ruminal degradation of rations for dairy cows [Efecto de enzimas fibrolíticas exógenas en la degradación ruminalin vitro de dietas para vacas lecheras]

To determine the effect of an exogenous fibrolytic enzyme on in vitro dry matter and neutral detergent fiber degradation (IVDDM and IVDNDF, respectively), three total mixed rations with 40:60, 50:50, 60:40 forage:oncentrate ratio (F: C), each with or without enzyme, were incubated for 3 to 72h. A randomized block design with a factorial arrangement of treatments 3×2×6 was utilized (FC ratios of 40:60, 50:50, 60:40; enzyme, 0 and 2g·kg -1 DM; incubation times of 3, 6, 12, 24, 48 and 72h). The IVDDM was higher (P≤0,05) in rations with F:C of 60:40 than 50:50 or 40:60 F:C. The IVDNDF was higher with 50:50 than 40:60 or 60:40. The F:C × enzyme × incubation time suggests that the main effect of the fibrolytic enzymes on IVDDM and IVDNDF were found during the first 12h of incubation in the diet with the highest fiber content.

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