Inoculants to Enhance the Ruminal Degradation of Small-Grain Forage

Abstract

Fibrolytic enzymes and microbial inoculants have the potential to improve fiber degradability. A 2 × 2 × 2 factorial experiment was conducted to determine the nutritive value, ruminal degradability, and degradation rates of wheat (Triticum aestivum L.) and oat (Avena sativa L.) pretreated with fibrolytic enzyme (xylanase plus cellulase: XC) or bacterial [Promote ASB (Lactobacillus buchneri and L. plantarum); PRO] inoculants at two maturities. Forage was harvested twice during the tillering stage (H1 and H2) and a third time as stover (H3). Forage from H1 had less neutral detergent fiber (NDF; 43.8% dry-matter [DM] basis) and acid detergent fiber (ADF; 31.2% DM basis) and greater in vitro true digestibility (IVTD; 78.5%) concentrations than H3 (69.0 and 45.3% DM basis, and 51.9%, respectively). The IVTD was greater for oat (55.0%) than wheat (50.7%). Chemical composition was not affected by inoculant; however, inoculant did affect ruminal degradability and degradation rates. Potentially degradable DM, NDF, and ADF and effective ruminal degradability were greater for wheat and oat at tillering. Treatment of oat or wheat with XC or PRO enhanced potential degradability and reduced undegradable fractions. Both XC and PRO may be used to degrade the fiber fractions of small-grain forage.