Four ruminally cannulated Holsteinsteers (749 lb) were used in a 4 × 4 Latinsquare experiment to evaluate the benefitsof supplementing digestive enzymes anddietary buffers to a soybean hull-based dietfed to steers once daily at 15.4 lb/day (asfed basis). Treatments were arranged as a2 × 2 factorial with factors being two levels(0 and 3 grams/day) of digestive enzymesand two levels (0 and 93 grams/day) ofdietary buffers. Buffers and enzymes werethoroughly mixed with the soybean hull-baseddiet to provide a completely mixedration. Digestive enzyme or buffersupplementation increased (P≤0.06) dietdigestibilities of dry matter, organic matter,neutral detergent fiber, and acid detergentfiber. Addition of buffer also increased(P≤0.06) digestibilities of glucose,mannose, arabinose, xylose and galactose,whereas enzyme supplementation increased(P=0.03) xylose digestibilities and tendedto increase (P=0.10) arabinosedigestibilities. The addition of enzymesand buffer to the soybean hull-based dietdid not alter passage of liquid or solidsfrom the rumen and therefore cannotaccount for any of the responses indigestion. Also, ruminal pH was notaltered when steers were supplementedwith digestive enzyme and(or) buffer. Thelack of response in pH to buffer wassurprising, because the observed effect ofbuffer on fiber digestibilities would havebeen expected to be a result of amoderation of the ruminal pH. Resultsfrom this experiment demonstrated thatboth digestive enzyme and buffersupplementation improved the digestibilityof soybean hull-based diet, and responseswere greatest when both additives weresupplemented together.
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