effects of a multi - strain Bacillus species – based direct - fed microbial on growth performance , nutrient digestibility , blood profile , and gut health in nursery pigs fed corn – soybean meal – based diets 1

This experiment was conducted to investigate the effect of a Bacillus spp.–based directfed microbial (DFM) on growth performance, apparent total tract digestibility (ATTD), blood profile, intestinal histomorphology, and fecal gas emission in piglets fed corn and soybean meal–based diets. The DFM product was based on 1 strain of Bacillus subtilis and 2 strains of Bacillus amyloliquefaciens and formulated to supply 1.5 × 105 cfu/g of feed. A total of 128 piglets ([Yorkshire × Landrace] × Duroc; 6.8 ± 0.6 kg BW; weaning age: 24 d) were housed in groups (4 pigs/pen, 2 barrows and 2 gilts) and fed diets (n = 16) without or with DFM in a 2-phase feeding program: d 0 to 14 (phase I) and 15 to 42 (phase II). Feed intake and BW were measured weekly. At the end of each phase, samples for blood urea nitrogen (BUN), blood creatinine, ATTD, and fecal noxious gas emission were taken. At termination, 12 piglets per treatment were killed to access intestinal tissues for histomorphology. Overall, pigs fed DFM had a greater (P < 0.05) G:F than pigs fed the control diet. In phase I, pigs fed DFM showed a greater (P < 0.05) ADG and lower (P < 0.05) concentration of BUN and fecal ammonia emission than the control group. In phase II, a greater (P < 0.05) ATTD of nitrogen and longer (P < 0.05) duodenum and jejunum villi were observed in pigs fed the DFM diet compared with the control group. In conclusion, inclusion of DFM improved growth performance and villi length of the duodenum and jejunum in nursery pigs. Furthermore, DFM enhanced protein utilization as demonstrated by increased nitrogen digestibility, lower BUN, and lower fecal ammonia release.