Immunomodulatory effects of whole yeast cells and capsicum in weanling pigs challenged with pathogenic Escherichia coli

Abstract Text:

Global concerns over antibiotic resistance triggered the development of nutritional technologies to support animal health. In weaned pigs, enterotoxigenic Escherichia coli infections are common. In this study, we sought to quantify the combined dietary effects of whole yeast cells (WYC) and capsicum (CAP) on performance and immune indices in weanling pigs experiencing an E. coli infection. Weanling pigs (32 barrows and 32 gilts, 21 d of age, 5.90 ± 1.03 kg BW) were allotted to experimental treatments in a randomized complete block design based on genetics, sex, and initial BW. Four pigs were individually housed within each containment chamber and assigned to 1 of 4 dietary treatments (n=13), which included a control diet without or with 0.2% WYC (CitriStim, ADM, Decatur, IL) or 10 ppm of CAP, provided either alone or in combination. After receiving diets for 13 d, pigs were orally inoculated with F18⁺ E. coli and maintained on the same diets for an additional 10 d; a separate cohort of pigs (n=12) receiving the control diet was sham-inoculated using PBS. Body and feeder weights were recorded, and fecal swabs collected, on 0, 5, and 10 d post-inoculation (DPI), with blood sampled at 7 DPI for clinical outcomes. Data were analyzed as a 2-way ANOVA (infected pigs only), with a separate comparison between unchallenged and challenged control-fed pigs. While no interactive effects were observed for growth performance, main effects revealed that WYC increased (P<0.05), and CAP decreased (P<0.05), ADFI 0-10 DPI; reciprocal effects were observed for G:F due to a lack of differences in ADG. The challenge E. coli strain was undetectable in fecal swabs on 0 and 10 DPI, but differed between unchallenged and challenged control-fed pigs at 5 DPI. Total bacterial counts were lower (P=0.02) at 5 DPI in pigs fed CAP-containing diet, and the combination of additives elicited higher total bacteria counts compared with either additive alone (interaction, P=0.03) at 10 DPI. Blood leukocyte counts were increased in infected pigs receiving the combination of additives compared with infected pigs on other dietary treatments (interaction, P=0.04), and addition of WYC increased lymphocyte counts (main effect; P=0.01), at 7 DPI. Overall, these data indicate that WYC and CAP have different effects on ADFI; individually or in combination may affect the immune response in weaned pigs experiencing an enterotoxigenic E. coli infection.

Keywords:

Escherichia coli, yeast, essential oils