PS5-8. Effects of a Bacillus -based Feed Additive in Nursery Pig Diets Containing Low or High Levels of Soybean Meal

Abstract A total of 4,320 nursery pigs (PIC 337 × 1050, initially 6.7±0.09 kg) were used in a 42-d study to determine the effects of a Bacillus-based feed additive on growth performance and fecal dry matter (DM) in diets with low or high levels of soybean meal (SBM). At approximately 21 d of age, pigs were weaned, blocked by BW and allotted to one of four dietary treatments in a randomized complete block design with 20 replications per treatment. Diets were formulated in three phases and fed from d 0 to 7, 7 to 21, and 21 to 42, respectively. The four treatments were arranged in a 2 × 2 factorial with main effects of bacillus (none or 106 colony-forming units (CFU)/g of complete feed; Argis, Kent Nutrition Group, Muscatine, IA) and SBM level (low or high). On d 14 of the study, fecal samples were collected from 3 pigs per EU to determine fecal DM. From d 0 to 7, a SBM×bacillus interaction was observed (P 0.05) for ADFI where pigs fed high SBM had decreased ADFI compared to pigs fed low SBM when bacillus was not in the diet. When bacillus was in the diet, SBM level did not affect ADFI. Pigs fed high SBM had decreased (P 0.05) ADG and G:F compared to pigs fed low SBM. From d 7 to 21, a SBM×bacillus interaction was observed (P 0.05) for ADG and G:F where pigs fed high SBM had increased ADG and G:F compared to pigs fed low SBM when bacillus was not in the diet. When bacillus was in the diet, SBM level did not affect ADG, and there was a smaller increase in G:F in pigs fed high SBM compared to those fed low SBM. Overall, a SBM×bacillus interaction was observed (P 0.05) for G:F where pigs fed high SBM had increased G:F compared to pigs fed low SBM when bacillus was not in the diet. When bacillus was in the diet, SBM level did not affect G:F. Pigs fed high SBM had decreased (P 0.05) fecal DM compared to pigs fed low SBM. A SBM×bacillus interaction was observed (P 0.05) for total removals and mortality where pigs fed high SBM had increased total removals and mortality compared to pigs fed low SBM when bacillus was not in the diet. When bacillus was in the diet, SBM level did not affect total removals and mortality. In summary, high SBM had negative effects on phase 1 growth, fecal DM, and removals and mortality but improved growth in later phases. When bacillus was not in the diet, high SBM increased overall G:F and removals and mortality. When bacillus was in the diet, SBM level did not affect G:F or removals and mortality.