The effect of treating forages with fibrolytic enzymes on its nutritive value and lactation performance of dairy cows.

Forages (corn silage and alfalfa hay) were sprayed with liquid enzymes prior to combining with a concentrate to form a total mixed ration (50% forage:50% concentrate, dry matter basis) and fed to lactating cows. In the first year, treatments were 1) no enzymes, 2) an enzyme complex containing 3500 carboxymethyl cellulase (CMCase) and 16,000 xylanase units per kilogram of forage dry matter, or 3) an enzyme complex containing 8800 CMCase units and 40,000 xylanase units. In the second year, the treatments were 1) no enzymes, 2) an enzyme complex as in yr 1 containing 3700 CMCase and 14,000 xylanase units, or 3) an enzyme complex using an alternative cellulase and containing 3600 CMCase and 11,000 xylanase units. In the first year, cows fed diet 2 tended to produce more milk (39.5 kg/d) than those fed diet 1 (37.0 kg/d) or those fed diet 3 (36.2 kg/d). The high level of enzyme treatment in diet 3 decreased the output of milk protein and fat compared to the low level of enzyme treatment. In the second year, cows fed diet 3 produced more milk (35.4 kg/d) than did those fed diet 1 (32.9 kg/d) and numerically more than those fed diet 2 (33.6 kg/d). Milk fat and protein were similar among treatments but numerically lower for cows fed enzyme-treated forages. Dry matter intake (kg/d) was similar among treatments in both years. Spraying certain doses and combinations of enzymes directly onto forages prior to feeding can improve milk yields but enzyme sources and dose levels are of critical importance.