Effect of an inoculant and hydrolytic enzymes on fermentation and nutritive value of whole crop barley silage

Whole crop barley forage was chopped, wilted to 350 g/kg dry matter (DM) and treated with water (control), inoculant (Agri-Sile®), enzymes (primarily cellulase and amylase activities) or inoculant + enzymes (SilagePro®) prior to ensiling. Triplicate laboratory silos (3 l) for each silage (denoted C, I, E and I + E, respectively) were opened after 0.5, 1, 2, 3, 4, 7, 14 and 112 days for chemical and microbiological analyses. Silos were weighed after sealing and before opening for estimation of DM loss. A feedlot experiment was also conducted with treatments C, I and I + E, in which barley forage was ensiled in 3 m × 61 m plastic Ag Bags®. Silage samples were collected from bags after 115, 136 and 157 days of ensiling, compiled and used to determine in situ disappearance of DM and neutral detergent fibre (NDF). Inoculation accelerated the decline of silage pH: treatments I and I + E attained pH 4.0 by day 3, whereas C and E were at pH 4.2 and 4.25, respectively, at day 14. At day 112, water soluble carbohydrates (g/kg DM) were lower (P < 0.05) in I and I + E (22.9 and 22.4, respectively) than in C and E (29.7 and 32.7, respectively). Crude protein (CP) contents were higher (P < 0.05) in I and I + E (132 and 126 g/kg DM, respectively) compared with C and E (117 and 118 g/kg DM, respectively). Also, less NH3-N (as g/kg of total N) was present (37.4 and 44.9 in I and I + E, versus 75.0 in C and 66.8 in E; P < 0.01), suggesting reduced proteolysis with additives. At day 112, C and E had more (P < 0.01) acetate and total (TB) and lactic acid producing (LAB) bacteria than did I or I + E. Lactate (g/kg DM) was higher (P < 0.05) in I + E (106.5) than in E (91.9) or C (83.7), and intermediate (96.0) in I. Treatment with either additive (I or I + E) did not (P > 0.05) alter the rate or extent of DM of NDF silage digestion, but I + E did increase (P < 0.01) the soluble NDF fraction as compared to C or I. In the feedlot study, DM intake did not differ among treatments, but average daily gain (ADG) by steers fed diets I and I + E was higher (P = 0.1), by 4.8% and 7.6%, respectively, than ADG by steers fed diet C. Feed efficiency of steers fed I + E silage was improved (P = 0.01) relative to those fed C. The bacterial inoculant clearly enhanced fermentation and retention of DM and nutrients in barley silage and the combination of I + E improved the feed efficiency of cattle fed barley silage.