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Improved growth performance of nursery pigs fed diets supplemented with a Bacillus subtilis-based direct-fed microbial feed additive
Three experiments were done to determine the efficacy of a Bacillus subtilis-based direct-fed microbial (DFM) feed additive for improving growth performance of nursery pigs. All experiments were done with PIC 337 × C29 terminal pigs weaned at approximately 20 d of age and 6 kg body weight. In all experiments, pens of pigs were blocked by weight and randomly allotted to experimental treatments from within block (replicate). Experiment 1 compared the DFM (Visano™ Nursery, JBS United, Inc.) to a control in corn-SBM diets with 14 replicates of 10-12 pigs/pen from 7 to 27 d postweaning. All pigs were fed a common complex Phase 1 nursery diet prior to the start of this experiment. Experiment 2 compared the DFM to a control in corn-SBM-DDGS diets with 11 replicates of 25-28 pigs/pen from 1 to 41 d postweaning. Experiment 3 compared the DFM to a control and a medicated feed additive (MFA)-containing treatment in corn-SBM-DDGS diets with 11 replicates of 10-12 pigs/pen from 1 to 38 d postweaning. The MFA consisted of 55 mg/kg carbadox from d 1-7, 441 and 38 mg/kg CTC and tiamulin, respectively, from d 8-21, and 28 mg/kg carbadox from d 22 to 38. The DFM was supplemented to final diets at 0.05% of complete feed from a premix of analyzed cfu concentration. Body weights, weight gain, feed intake, and feed efficiency metrics were collected in each experiment, and data were analyzed as a randomized complete block design. In Experiment 1, there was a trend (P < 0.10) towards a lower feed/gain ratio (1.4%; 1.41 vs 1.39 kg/kg) in the DFM treatment group. In Experiment 2, supplementation of the Bacillus DFM increased (P < 0.05) growth rate by 5% (0.36 vs 0.34 kg/d) and increased (P = 0.06) d 41 body weight by 0.5 kg. In Experiment 3, the Bacillus DFM increased (P < 0.05) growth rate by 10% over the control (0.29 vs 0.26 kg/d) and reduced (P < 0.05) feed/gain ratio by 5% (1.45 vs 1.52 kg/kg), whilst the medicated feed additive treatment showed 25% greater (P < 0.05) weight gains and 10% lower (P < 0.05) feed/gain ratios than the control treatment. Dietary inclusion of the Bacillus-based DFM was efficacious in increasing weight gain and improving overall growth performance in nursery pigs fed out to 6 wks post-weaning.
Keywords: Bacillus subtilis, pigs, direct-fed microbial