Ciência Animal Brasileira (Oct 2010)
EFEITO DE ENZIMAS FIBROLÍTICAS SOBRE A DEGRADAÇÃO MICROBIANA RUMINAL DA FIBRA DE CANA-DE-AÇÚCAR
Abstract
Aiming to study the limiting factors for degradation of sugarcane fiber to be used as cattle feed, sugarcane fibrous components were fractioned in neutral- and acid-detergent fibers (respectively, NDF and ADF). Whole sugarcane and its fibers were incubated with rumen bacteria, in presence or absence of fibrolytic enzymes (Fibrozyme, Alltech Inc.). Microbial growth and total bacteria count were determined, and the growth rate, generation rate, lag time, and degradability were also determined. Results were analyzed in randomized block design, with a 2x3 factorial arrangement, with two doses of enzymes, and three substrates, using four replications for incubation. The highest microbial growth was observed for whole sugarcane, and the lowest for its fibers. The in vitro degradability was 0.701, 0.392 and 0.191, respectively for whole sugarcane, NDF and ADF (P<0.01). ADF fraction with the addition of fibrolytic enzyme had its degradability increased from 0.387 to 0.425 (P<0.01). Microbial growth was limited in fibrous fractions, possibly due to lignification grade of cell walls. The highest in vitro degradability of fibrous fractions is related to the presence of soluble sugars. Addition of fibrolytic enzymes increased the maximum microbial growth and ADF degradability, indicating that it could be a potential addictive to enhance diets containing sugarcane.
