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Effect of bacterial inoculation on feedlot performance with or without the addition of yeast product
A finishing study using 320 yearling steers (initial BW = 417 kg ± 22.7) evaluated the effect of using a silage inoculant or not on performance and carcass characteristics. Treatments were designed as a 2×2×2 factorial arrangement with factors being no inoculant (CON) or use of inoculant (buchnerii spp.; B500) at silage harvest, silage fed at 15 or 40% of diet DM, and presence (LevSC) or absence (noLevSC) of Levucell SC yeast product fed at 14.2 g/d. Performance data were analyzed with pen as the experimental unit. The feeding experiment started 236 d post silage harvest. Steers were blocked by BW into light, middle and heavy blocks, and assigned randomly to one of 40 pens within block (8 steers/pen). Pens were assigned randomly to one of 8 dietary treatments (5 replications/treatment). Steers were limit fed for 5 d at approximately 2% BW and two day weights were collected and averaged for initial BW. There was very little numeric differences in DM, CP, pH, or organic acids between the CON and B500; however, no statistical analysis was performed due to only one silage bunker per treatment. There was a three-way interaction for final live BW, HCW, ADG, and G:F (P < 0.05). Greater inclusion of silage in the diet increased DMI (P < 0.01). At 15% silage inclusion, the B500 LevSC treatment had the lowest ADG, 1.79 kg/d, similar to both CON treatments (P ≥ 0.55) and less than the B500 noLevSC treatment, 1.90 kg/d (P = 0.05). At 40% silage inclusion, the CON LevSC and B500 noLevSC treatments had the numerically least ADG, but all treatments were similar (P ≥0.06), averaging 1.79 kg/d. At 15% silage inclusion, the B500 LevSC treatment had the lowest G:F, 0.147 (P = 0.04), all other treatments were similar, averaging 0.152 (P ≥ 0.16). At 40% silage inclusion, all treatments had similar G:F, averaging 0.141 (P ≥ 0.07). At 15% silage inclusion, the CON LevSC treatment had the numerically greatest HCW, 402 kg, similar to B500 noLevSC and CON noLevSC treatments (P ≥ 0.07) and greater than the B500 LevSC treatment, 394 kg (P < 0.01). At 40% silage inclusion, the greatest difference between treatments was observed with the CON LevSC and B500 LevSC treatments, 389 and 397 kg, respectively (P = 0.05). Although there were numerical differences between treatments, there were no clear statistical advantages for any one treatment for all performance measurements.
Keywords: corn silage, inoculant, yeast