6 Saccharomyces boulardii does not alter the concentration of fecal immunoglobulins in clinically healthy zoo-managed zebras

Nondomestic equids, such as zebras, experience gastrointestinal (GI) issues similar to domestic horses, including diarrhea, colitis, and colic. The probiotic yeast strain, Saccharomyces boulardii (SB), has been shown to mitigate or prevent GI-related illnesses in humans and other animals. To reduce or prevent infectious pathogens, SB acts by stimulating secretory immunoglobulin (Ig) A production in the GI tract. Evidence of this immunomodulatory effect is limited in horses and zebras. The aim of this study was to characterize IgA, IgG, and IgM concentrations in fecal samples from zebras. We hypothesized that SB would result in greater fecal IgA in zoo-managed zebras. Nine clinically healthy zebras (mean ± SEM, 344.3 ± 22.7 kg; 10.7 ± 2.6 y), located in 5 different enclosures across Disney's Animal Kingdom®, were fed 3 dietary treatments in a replicated switchback design. The 8-wk study was comprised of 2-wk periods consisting of a control (CON) week followed by a treatment week of either wheat bran (WB) or WB plus SB (WBSB). The CON diet was each zebra's regular ration which included timothy and bermudagrass hays, forage-based pellets, and enrichment items (e.g., carrots, apples). The WB treatment included CON plus WB at 0.34–2.4% of total DM intake. The WBSB treatment consisted of CON, WB, and SB (1.3 × 109 cfu/g; fed daily at 6.67 mg/kg BW). Zebras had access to water, salt blocks, and pasture forage. Freshly voided fecal samples were collected at the end of each week, homogenized and compressed to extract fecal liquid. Fecal IgA, IgG, and IgM were measured by equine-specific ELISA. Data were analyzed using mixed model ANOVA. Mean (±SE) IgA, IgG, and IgM concentrations across treatments were 9.51 (±1.68), 0.43 (±0.36), and 0.17 (±0.03) g/mL fecal liquid, respectively. Voluntary consumption of SB varied by individual zebra. Fecal IgA (P = 0.54), IgM (P = 0.57), and IgG (P = 0.54) did not differ between treatments in zebras (n = 5) with 100% SB consumption. Enclosure location appeared to affect fecal IgA (P