82 Responses to a combined exercise and transport stressor following dietary supplementation of anti-endotoxin IgY in mature horses

Abstract

Immunoglobulin Y elicits positive effects in domestic livestock with gastrointestinal or inflammatory diseases; however, there are limited studies in horses. To test the hypothesis that dietary anti-endotoxin IgY (IgY) has a positive effect on gastrointestinal health and mitigates systemic inflammation in horses undergoing exercise, 30 stock-type horses (578 ± 59 kg BW; 14 ± 3 yr) were used in a completely randomized design. Horses were stratified by BW, age, and sex and then randomly assigned to treatments: 0 g/d IgY (CON; n = 10), 1 g/d IgY (TRT1; n = 10), or 2 g/d IgY (TRT2; n = 10). Horses were fed every 12 h, with dietary treatments (Camas Inc., Le Center, MN) top-dressed on the morning concentrate for 33 d. Horses were maintained in dry lots with ad libitum access to Coastal bermudagrass hay. Horses were exercised 5 d/wk for 1 h. On d 0 and 30, BW and BCS were recorded, and blood was collected for complete blood cell count (CBC) and serum blood chemistry. On d 32, horses were transported 270 km and underwent a 3.2 km exercise stressor on concrete at a walk with maximum 15 min of trot. Whole blood, serum, and fecal samples collected via rectal palpation were obtained pre-, post-, and 24 h post-trailering. Fecal pH was determined by a portable meter, and serum cytokine (TNFα, IL-4, IL-10, IL-1β, IL-17, IFN-α, IFN-γ) and chemokine (CCL2, 3, 5 and 11) concentrations weremeasured using a multiplex platform. Whole blood DNA was extracted using a commercial DNA extraction kit. For gut permeability analysis, 16s rDNA was analyzed via qPCR and calculated as fold change from d 0. Data were analyzed using PROC MIXED of SAS v9.4. Dietary IgY did not affect BW, BCS, blood chemistry, or CBC (P ≥ 0.17). Fecal pH decreased over time (P ≤ 0.01). There was no treatment × time interaction for 16S rDNA (P = 0.45). Dietary treatment affected circulating 16S rDNA (P < 0.01) where TRT2 (1.89-fold) was greater than CON (0.70-fold), and TRT1 (1.24-fold) was intermediate. A significant time effect (P = 0.001) was observed for 16S rDNA where fold change decreased after the stressor from 1.90-fold for pre-, to 1.02 for post-, and 0.92 for 24 h post- trailering. There tended to be a treatment × time interaction (P = 0.08) for CCL3, as CON was greater at 24 h and TRT2 declined post-trailering, returning to baseline by 24 h. Levels of CCL5 decreased (P < 0.01) and TNFα tended to decline (P = 0.06) through 24 h post trailering in all treatment groups. Other cytokines and chemokines were non-detectible. Despite greater circulating 16s rDNA with higher treatment dosages, there was no effect on systemic inflammatory markers.