Short-term effect of supplemental yeast extract without or with feed enzymes on growth performance, immune status and gut structure of weaned pigs challenged with lipopolysaccharide.

Background: This study investigated the response of piglets receiving a yeast extract without or with a multi-enzyme mixture compared with an antimicrobial growth promoter (AGP) on performance, immune status and gut structure after an lipopolysaccharide (LPS) challenge. Thirty-six pigs were allotted to six treatments including: a non-challenged control (NCC); LPS-challenged control (CC); CC + AGP; CC + yeast extract; CC + enzymes; and CC + enzymes + yeast extract. On d 7, pigs were bled and thereafter injected with LPS or sterile saline. Blood samples were collected at 6, 48, and 96 h post-challenge. After 96 h post-challenge, pigs were euthanized to obtain duodenal, jejunal and ileal samples.

Results: Overall (d 1 to 11), compared with CC pigs, AGP attenuated the LPS-induced reduction in ADG ( = 0.004), ADFI ( = 0.03) and gain/feed ratio ( = 0.01). At 6 h post-challenge, AGP pigs had lower plasma urea N (PUN;  = 0.02) and serum TNF- α concentration ( = 0.07), and higher platelet count ( = 0.04) and serum IL-10 concentration ( = 0.02) than CC pigs. At 48 h post-challenge, AGP pigs had lower PUN ( = 0.02) than CC pigs, whereas enzymes + yeast extract interacted non-additively ( = 0.001) to reduce PUN. At 96 h post-challenge, AGP pigs had lower PUN ( = 0.02) and higher duodenal ( = 0.03), jejunal ( = 0.01) and ileal ( = 0.07) villus height than CC pigs. In addition, enzymes + yeast extract interacted additively and non-additively to reduce ileal IFN-γ ( < 0.0001) and IL-10 ( = 0.012) expression, respectively. Generally, no differences ( > 0.10) were observed between AGP and enzymes + yeast extract pigs on other measured parameters except for the downregulation of ileal IFN-γ ( < 0.0001) and TNF-α ( = 0.003) in enzymes + yeast extract pigs at 96 h post-challenge.

Conclusions: The LPS challenged piglets receiving enzymes + yeast extract showed beneficial responses in gut structure and immunity commensurate with those receiving antibiotics, though the latter had better overall growth performance.