LAUSR

Two experiments were conducted to determine the impact of various combinations of yeast-based direct fed microbials (DFM) in diets fed to nursery pigs weaned from sows fed lactation diets with or without yeast additives. In Exp. 1, 340 weaned pigs, initially 5.1 kg ± 0.02, were used to evaluate previous sow treatment (control vs yeast additives) and nursery diets with or without added yeast-based DFM on growth performance and antimicrobial resistance (AMR) patterns of fecal Escherichia coli. Treatments were arranged in a 2 × 2 factorial with main effects of sow treatment (control vs. yeast-based pre- and probiotic diet; 0.10% ActiSaf Sc 47 HR+ and 0.025% SafMannan, Phileo by Lesaffre, Milwaukee, WI) and nursery treatment (control vs. yeast-based pre- and probiotic diet; 0.10% ActiSaf Sc 47 HR+, 0.05% SafMannan, and 0.05% NucleoSaf from d 0 to 7, then concentrations were decreased by 50% from d 7 to 24) with 5 pigs per pen and 17 replications per treatment. Progeny from sows fed yeast additives had increased (P < 0.05) average daily gain (ADG) from d 0 to 24 and d 0 to 45. However, pigs that were fed yeast additives for the first 24 d in the nursery tended to have decreased d 0 to 45 ADG (P = 0.079). Fecal E. coli isolated from pigs from the sows fed yeast group had increased (P = 0.034) resistance to nalidixic acid and a tendency for increased resistance to ciprofloxacin (P = 0.065) and gentamicin (P = 0.054). Yet, when yeast additives were added in the nursery there was reduced (P < 0.05) fecal E. coli resistance to azithromycin and chloramphenicol. In Exp. 2, 330 weaned pigs, initially 5.8 kg ± 0.03, were used to evaluate diets with two different combinations of DFM on growth performance. Treatments were arranged in a 2 × 3 factorial with main effects of sow treatment (same as described in Exp. 1) and nursery treatment (control; YCW, 0.05% of SafMannan from d 0 to 38 and NucleoSaf at 0.05% from d 0 to 10 and 0.025% from d 10 to 24; or DFM, 0.10% MicroSaf-S from d 0 to 38 and NucleoSaf at 0.05% from d 0 to 10 and 0.025% from d 10 to 24) with 6 pigs per pen and 8 to 10 replications per treatment. From d 0 to 10 post-weaning, progeny of sows fed yeast additives had increased (P < 0.05) ADG and G:F. In conclusion, feeding sows yeast through lactation improved offspring growth performance in the nursery. While feeding live yeast and yeast extracts reduced nursery pig performance in Exp. 1, feeding DFM improved growth later in the nursery period in Exp. 2.