Abstract
This study evaluated the effects of novel silage inoculants containing lactic acid bacteria (LAB) and fibrolytic enzymes on ensiling, aerobic stability (AS), and the performance of growing beef cattle. Whole-plant corn forage was either uninoculated (CON) or inoculated with a mixture of LAB containing (cfu g(-1) fresh forage) 1.5 × 10(5) L. hilgardii (CNCM I-4785), 1.5 × 10(5) L. buchneri (NCIMB 40788) and 1.0 × 10(5) P. pentosaceus (NCIMB 12455) for a total of 4.0 × 10(5) cfu g(-1) fresh forage LAB (IB), or a combination of IB plus fibrolytic enzymes (xylanase + β-glucanase) (IC). All treatments were ensiled in mini-silos, whereas CON and IC were also ensiled in silo bags for the growth performance study. Total bacteria (TB) counts were lower (P = 0.02) for IC than CON after 14 d of ensiling, whereas TB counts of IC and IB were greater (P ≤ 0.01) than CON after 60 d of ensiling in mini-silos. The LAB in IC and IB ensiled in mini-silos were greater than CON on d 60 (P ≤ 0.01) and 90 (P ≤ 0.001) of ensiling and after 3 d (P ≤ 0.01) of aerobic exposure (AE). Silage pH of IC ensiled in silo bags was lower than CON on d 3 (P < 0.01), 7 (P < 0.001), and 14 (P = 0.02) of AE. Yeast counts were lower for IC than CON in terminal silage (P < 0.001), and after 3 (P < 0.001) and 7 d (P < 0.01) of AE. Acetate (AC) concentrations were higher (P ≤ 0.02) for IC than CON throughout AE, whereas lactate (LA) concentrations of IC were greater than CON on d 3 (P < 0.001), 7 (P < 0.01), and 14 (P < 0.001) of AE. Greater AC concentration and lower yeast counts resulted in greater (P < 0.001) stability for IC ensiled in silo bags than CON after 14 d of AE. Growth performance of steers was similar (P > 0.05) as the nutrient composition of silage was similar across diets. Improved AS of IC could potentially have a greater impact on DMI, production efficiency, and growth performance in large-scale commercial feedlot operations where silage at the silo face may be exposed to air for longer periods of time.