Direct fed microbials (DFM) are defined as live microorganisms that offer a health benefit for the host when administered in appropriate and regular quantities. Bacillus-based DFM are aerobic, spore-forming bacteria that may enhance the host animal’s immune response and improve growth performance in weanling pigs. Bacillus spp. also produce extracellular enzymes that may enhance digestibility and absorption of nutrients.

An experiment was, therefore, conducted to test the hypothesis that two DFM containing Bacillus strains (provided by Chr. Hansen A/S, Horsholm, Denmark) improve the apparent ileal digestibility (AID) of AA, CP, and GE, the apparent total tract digestibility (ATTD) of CP and GE, and hindgut digestibility of CP and GE when fed to growing pigs.

Experimental design

Twenty-four growing barrows (22.69 ± 1.48 kg initial body weight) with a T-cannula in the distal ileum were individually housed and randomly allotted to a 24 × 3 incomplete Latin square design with 24 pigs and three 21-d periods. There were 8 pigs per diet in each period for a total of 24 observations per diet. Three diets that were based on corn, soybean meal, and distillers dried grains with solubles were formulated. The control diet contained no DFM, but 2 additional diets contained 2 different bacillus strains (DFM1 or DFM2). Feed was provided in mash form in 2 daily meals at 0800 and 1600 h. The initial 12 d of each period was the adaptation period to the diet. Fecal and urine samples were collected from d 13 to 18, and ileal digesta were collected for 8 hours on d 20 and 21.

Results

There were no differences in ATTD of CP among diets, but the AID of CP was reduced (P < 0.05) in the DFM2 diet compared with control and DFM1 diets (Table 1). Therefore, the hindgut digestibility of CP was greater (P < 0.005) in pigs fed DFM2 diet compared with the other 2 diets. The AID of total indispensable, total dispensable, and total AA was greater (P < 0.05) in the DFM1 diet compared with the control diet. There were no differences among diets in ATTD of GE, but the AID of GE was greater for the DFM1 diet than for the control and the DFM2 diets (P < 0.001). Therefore, the hindgut digestibility of GE was less (P < 0.05) in the DFM1 diet compared with the other diets. The DE on a DM basis for the DFM2 diet was greater (P < 0.05) compared with the control and the DFM1 diets.

Key points

• Inclusion of Bacillus-based DFM in diets fed to pigs may increase the AID of AA and energy.
• There are differences among sources of Bacillus spp. in their impact on AA and energy digestibility.

Table 1. Apparent total tract digestibility (ATTD) of CP and GE, apparent ileal digestibility (AID) of CP, AA, and GE, hindgut digestibility (HGD) of CP and GE, and concentrations of DE, ME in the control diet and in 2 diets containing direct fed microbials (DFM1 and DFM2), as-fed basis

^a-bValues within a row lacking a common superscript letter are different (P ≤ 0.05).

This report is based on unpublished research by Laia Blavi and Hans H. Stein.