Stavric and Kornegay (1995) suggested that probiotics might be more effective in animals during microflora development or when microflora stability is impaired, however, other studies did not find improvement inpiglet performance with the supplementation of the diets of nursery pigs with Bacillus-based probiotics (Barker et al., 2003;Kritas and Morrison, 2004; Min et al., 2004; Kunavue and Lien, 2012).