Growth performance, organ weight, fecal scores, plasma, and ceca digesta microbial metabolites in growing pigs fed spent biomass of Pichia kudriavzevii

Growth performance, liver and spleen weight, plasma, and ceca digesta metabolites and incidences of diarrhea were investigated in growing pigs fed spent biomass of Pichia kudriavzevii. Ninety six barrows (~25 kg, 4 pigs/pen) were fed 1 of 4 experimental diets (n = 6) for 7 weeks. The diets were control, corn-, and soybean meal-based diet or control plus 2.5%, 3.75%, or 5.0% P. kudriavzevii. Diets were formulated to be isocaloric and iso nitrogenous. Feed intake and body weight (BW) were recorded weekly for calculation of average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). Fecal scores were taken 3 d/wk to assess incidence and severity of diarrhea. One pig/pen close to pen average was bled for plasma metabolites on days 7 and 49 and subsequently euthanized for spleen and liver weight, ileal and cecum digesta samples for concentration of short-chain fatty acids (SCFA). The concentration of crude protein, crude fat, and non-fiber carbohydrates in P. kudriavzevii biomass was 36.4%, 9.6%, and 50.8% DM, respectively. Inclusion of P. kudriavzevii tended (P = 0.06) to linearly reduce ADG from days 8 through 49 resulting in a trend (P = 0.06) for linear reduction in the final BW. The final BW was 79.0, 79.2, 76.8, and 75.5 kg for the 0%, 2.5%, 3.75%, and 5.0% P. kudriavzevii, respectively. Diets had no effect (P > 0.10) on ADFI, G:F, spleen, and liver weight throughout the entire experiment. On day 7, there was cubic (P = 0.03) decrease and quadratic (P = 0.02) increase in plasma concentration of creatinine and urea N, respectively. However, there were no (P > 0.10) diet effects on plasma metabolites on day 49. There was a tendency (P = 0.08) for linear increase in cecum digesta concentration of acetic acid. There were no diet effects (P > 0.10) on fecal score in the first 4 wk of feeding. In conclusion, feeding P. kudriavzevii yeast tended to depress growth and stimulate cecum fermentation at higher dose and had no detrimental effects on organ weights or plasma metabolites in growing pigs.