Apparent total tract digestibility, performance, and methane emissions in pigs maintained under different sanitary conditions and supplemented with antibiotic or Bacillus subtilis

Digestibility, performance, and initial methane production were evaluated in growing and finishing pigs. Assay 1 was carried out in experimental facilities. Sixty pigs, 30 barrows and 30 gilts (26.07 +/- 0.07 kg), were allotted randomly to treatments arranged in a 3 x 2 factorial design with three diets (control, Bacillus subtilis, and lincomycin) and two genders. In assay 2, 48 pigs (26.06 +/- 3.10 kg) were maintained in commercial farm and supplemented with B. subtilis and lincomycin. Performance and initial methane production were measured. In assay 3, 12 barrows (body weight = 26.55 +/- 1.25 kg) were housed in metabolism crates and fed control and B. subtilis diet to evaluate nutrient balance and energy. Gilts within experimental facility, fed control diet, had higher ADG (P < 0.05) compared with lincomycin diet, but there was no statistical difference with B. subtilis diet. Numeric variations on the first and second assays suggested some improvement on pig performance and a reduction on initial methane production when pigs were fed B. subtilis diet, compared with lincomycin diet. Protein digestibility increased (P < 0.05) with B. subtilis supplementation in the diet. Dietary supplementation with B. subtilis for growing and finishing pigs may improve performance and decrease N excretion and initial methane production.