Effects of a Yeast Feed Additive for Maternal Programming of the Postweaning Pig Microbiome

Abstract The objective of this study was to determine whether feeding live yeast to sows from day 85 of gestation and through lactation influences pig performance and microbiomes in the postweaning period. Three dietary treatments were imposed on mixed-parity sows during late gestation and lactation based on the inclusion level (%) of Actisaf Sc47 in corn/soybean meal-based diets: Control (C, 0%), Low (L, 0.1%), and High (H, 0.5%). Pigs (n = 240; 80/maternal dietary treatment group) were selected randomly at weaning (~19 days old) for further performance data collection throughout the nursery period. A subset of these pigs (n = 180; 60/maternal treatment group) were selected randomly for microbiome sampling through fecal swabs collected on days 4 (T1) and 28 (T2) postweaning. Pigs were housed in pens in a confinement nursery barn according to maternal dietary treatment group (10 pigs/pen; 0.28 m2/pig of floor space; 8 pens/treatment group). Treatment groups were kept separate from each other by maintaining one empty pen between treatment groups to prevent potential microbial cross-contamination. Pigs were balanced by litter, body weight, and sex during nursery allotment. Pigs had ad libitum access to water and a common industry-relevant diet, fed in four phases from weaning through day 42. Pigs were weighed individually at the end of each dietary phase (d4, d14, d28, d42). DNA was extracted from fecal swabs and sequenced on the MiSeq platform, targeting the V4 variable region of the 16S rRNA bacterial gene. Sequence data were analyzed using QIIME2 and DADA2, plus various packages within the R statistical software. Performance data were analyzed using repeated measures and generalized linear mixed models that included maternal treatment as a fixed effect, maternal parity as a random effect, and pen as the experimental unit. Daily weight gain was greater for L pigs (0.47 kg) compared with H pigs (0.42 kg; P < 0.05), while ADFI was increased for L pigs (0.57 kg) compared with both C and H pigs (0.49 and 0.47 kg, respectively; P < 0.05; see Table). No differences in microbiome diversity were observed at either time-point. However, microbiome composition differed based on maternal treatment group at both time-points (T1: PERMANOVA, R2 = 0.02, P=0.001; T2: PERMANOVA, R2 = 0.04, P=0.001). These results indicate that live yeast supplementation in sow diets in late gestation and lactation may have lasting effects on pig performance and microbiome composition in the post-weaning period.