PSVI-24 Immunological Effects of a Purified 1,3/1,6 β-glucan Supplementation in Retorted Canine Diets

Abstract

Abstract Yeast cell wall products are common functional ingredients capable of “priming” the immune system, specifically in reference to vaccine efficacy. Twenty-four adult, female Beagles were used in a completely randomized design. Three retorted diets were used: control diet (CON), CON plus β-glucan top-dressed daily upon time of feeding (C+B), and CON plus retorted β-glucan included in diet formulation (BG). Following a 7 d adaptation to CON, dogs were fed their respective treatment diets for 42 d and were challenged with an oral Bordetella bronchiseptica vaccine on d 14 with blood collections on d 0, 21, 28, and 42. The objectives of the present study were 1) to evaluate the effects of dietary inclusion of a yeast β-1,3/1,6 glucan (150 ppm) on apparent total tract digestibility (ATTD) of macronutrients, fecal microbiota, and peripheral blood mononuclear cells (PBMC; T-cells, B-cells, and monocytes) of adult dogs and, 2) to test the effects of retorting on the efficacy of these β-glucans. All diets were well-accepted by all dogs. ATTD of both dry matter and crude protein were greater (P < 0.05) for BG than CON and with greater (P < 0.05) energy digestibility for BG than both B+G and CON. Additionally, fecal short-chain and branched-chain fatty acids, ammonia, indole and phenol concentrations did not differ among treatments. No significant treatment by time interactions among treatment groups were observed for any analyzed PBMC. These data suggest that a 150 ppm inclusion of this yeast-derived β-glucan had no detrimental effects on ATTD, fecal characteristics and metabolites, nor any analyzed PBMC; however, due to the absence of differences in immune parameters among treatments, the effect of retorting on the efficacy of this product cannot confidently be assessed with these findings. Higher doses of yeast-derived β-glucan might be needed to elicit an immunological modulation in healthy adult dogs.