Stability of Bacillus and Enterococcus faecium 669 Probiotic Strains When Added to Different Feed Matrices Used in Dairy Production

SIMPLE SUMMARY: Direct-fed microbials (DFM), or probiotics, are live bacteria that confer health benefits to dairy animals and to bring such benefits, the bacteria must survive the feed preparation process. Hence, our objective was to evaluate the stability of Bacillus spp. and Enterococcus faecium 669 when included in different feed matrices. Three Exp. evaluated the recovery of a Bacillus-based (BOVACILLUS(TM)) on pelleted feed, mineral premix, and milk replacer. Another three Exp. evaluated the recovery of a DFM containing E. faecium 669 (LACTIFERM(®)) following its inclusion in a mineral premix and milk replacer prepared under different conditions. Overall, the recoveries of both Bacillus spores and E. faecium were stable and not impacted by the temperature used during the pelleting process, inclusion into a mineral–vitamin premix over 12 months, as well as when included into different milk replacer preparations. Altogether, the results from the present Exp. demonstrate, for the first time, the stability of a Bacillus-based and E. faecium-based DFM when included in different feed matrices often fed to the dairy cattle herd. These data provide novel information to the dairy industry in how to evaluate one of the features of a DFM (stability), as different results may be seen depending on the strains used. ABSTRACT: Few data are available evaluating the stability of direct-fed microbials (DFM) following their inclusion in different feed matrices. Therefore, six Exp. evaluated the recovery of bacilli spores (BOVACILLUS(TM); Exp. 1 to 3) and an Enterococcus faecium DFM (LACTIFERM(®); Exp. 4 to 6) when included in different feed preparations. The Bacillus-based DFM was included into pelleted feed prepared in different temperatures (75 to 95 °C), whereas both DFM were assessed in premix and milk replacer preparations. Bacillus spores and E. faecium recovery was evaluated through standard methodologies and data were reported as log10 colony forming units/gram of feed. The recovery of Bacillus spores was within the expected range and was not impacted by the temperature of pellet preparation (Exp. 1). Bacilli recovery was also stable up to 12 months in the premix and was not impacted by the temperature of milk replacer preparation. Regarding the Exp. with E. faecium (Exp. 4 to 6), its recoveries in the mineral premix and milk powder did not differ from T0 and were not impacted by the conditions of milk replacer preparation. These data are novel and demonstrate the stability of a Bacillus-based and an E. faecium-based DFM when included in different feed matrices often used in dairy production.