Effect of a trub, hops, and yeast mixture on jejunal mucosal immune status, oxidative stress status, structure, and growth performance of nursery pigs.

The craft brewing process results in the generation of co-products that have potential value in replacing traditional feedstuffs. A trub, hops, and yeast mixture (THYM) derived from the craft brewing process contains high levels of hop acids and yeast cells. The purpose of this study was to investigate the effects of increasing levels of THYM in diets of nursery pigs on the jejunal mucosal immune and oxidative stress status, morphological parameters, and growth performance. Thirty-two pigs (6.8 ± 0.3 kg body weight) weaned at 3-wk-of-age were allotted into 4 dietary treatments, using a randomized complete block design, with sex and initial body weight as blocks. The dietary treatment consisted of the basal diet supplemented with 0.0, 0.7, 1.4, or 2.1% THYM. The THYM replaced a mixture of 40% corn and 60% soybean meal in the basal diets. Pigs were fed for 28 d in 3 phases (9, 11, and 8 d, respectively). On d 28, all pigs were euthanized for sampling of jejunal tissue and mucosa to analyze immune and oxidative stress status. The increasing levels of THYM linearly increased (P < 0.05) gain to feed ratio of pigs, however, average daily gain and feed intake were not affected. Increasing levels of THYM linearly increased (P < 0.05) the relative gene expression of nucleotide oligomerization domain 2 and interferon-γ and tended to increase (P = 0.058) relative gene expression of Toll-like receptor 2 in the jejunum. Increasing levels of THYM did not affect the amount of immunoglobulins or oxidative damage products in the jejunal mucosa. The increasing levels of THYM linearly increased (P < 0.05) the percentage of Ki-67+ cells in the crypt, whereas villus height and crypt depth were not affected. Overall, the inclusion of the trub, hops, and yeast mixture obtained from the craft brewing process may have contributed to the increased rate of intestinal tissue repair following weaning stress, potentially explaining the improved gain-to-feed ratio in nursery pigs. Furthermore, the increasing inclusion of THYM increased the expression of genes related to innate immune system recognition and signaling without causing the elevation of inflammatory responses and humoral immune responses, or the associated oxidative stress.