Influence of an exogenous fibrolytic enzyme and the maceration process of a low-quality forage on digestion and ruminal function of dry Holstein cows

Abstract

FIVE CANNULATED DRY HOLSTEIN COWS (633 ± 81 KG) WERE USED TO EVALUATE THE POSSIBLE INTERACTION OF AN EXOGENOUS FIBROLYTIC ENZYME AND THE MACERATION PROCESS OF RICE STRAW ON THE RUMINAL DIGESTION AND FUNCTION PARAMETERS. TREATMENTS CONSISTED OF A CORNBASED CONCENTRATE DIET SUPPLEMENTED WITH 40% FORAGE AS: GROUND SUDAN GRASS HAY, GROUND RICE STRAW WITH AND WITHOUT ENZYME (15 G/D), AND MACERATED RICE STRAW WITH AND WITHOUT ENZYME (15 G/D). NO EFFECT (P > 0.10) ON DRY MATTER INTAKE WAS OBSERVED AMONG TREATMENTS. COMBINED ENZYME AND MACERATE INCREASED (INTERACTION, P < 0.05) NEUTRAL DETERGENT FIBER (NDF) RUMINAL DIGESTION RATE, AND TOTAL TRACT DIGESTION OF ACID DETERGENT FIBER (ADF). ENZYME ADDITION INCREASED (P < 0.50) RUMINAL DIGESTION OF ORGANIC MATTER (OM), ADF AND NDF, WITHOUT EFFECTS (P > 0.10) IN TOTAL TRACT DIGESTION. MACERATION DECREASED RUMINAL DIGESTION (P < 0.05) AND APPARENT TOTAL TRACT DIGESTION OF NITROGEN INTAKE (P < 0.01). EVEN WHEN, MACERATION TENDED TO DECREASE (P = 0.06) NDF RUMINAL DIGESTION, TOTAL TRACT DIGESTION OF NDF WAS INCREASED (P < 0.05). THE MACERATION INCREASED (P > 0.01) RUMINAL PASSAGE AND RUMINAL DIGESTION RATE OF NDF'S FRACTION IN RUMEN, AND DECREASED (P < 0.01) RUMEN'S TOTAL SOLID AND NDF CONTENT IN THAT SITE (P < 0.01). MEANWHILE, THE ENZYME INCREASED ONLY THE NDF DIGESTION RATE (P < 0.01). A GREATER TOTAL TRACT DIGESTION (P< 0.05) OF OM, NDF AND GROSS ENERGY (3%, 19% AND 4%, RESPECTIVELY) WAS OBSERVED IN THE SUDAN GRASS DIET, AND THESE EFFECTS REFL ECTED A GREATER CONTRIBUTION OF DIGESTIBLE ENERGY (P < 0.01). THERE WAS NO EFFECT OF THE TREATMENTS ON RUMINAL PH AND VOLATILE FATTY ACID PROFILE. IT IS CONCLUDED THAT EXOGENOUS FIBROLYTIC ENZYME SUPPLEMENTATION WORKS SYNERGISTICALLY WITH MACERATION TO ENHANCE THE FEEDING VALUE OF LOW QUALITY FORAGES.