Investigation of the nutritional and functional roles of a microencapsulated blend of botanicals on intestinal health and growth of nursery pigs challenged with F18+Escherichia coli.

The study aimed to evaluate the effects of increasing levels of a microencapsulated blend of botanicals (MBB) on the intestinal health and growth performance of nursery pigs challenged with F18+E. coli. Sixty-four nursery pigs (6.8 ± 0.3 kg) were assigned to 4 dietary treatments in a randomized complete block design, with initial body weight and sex as blocks, and fed for 28 d in 3 phases. Treatments were a basal diet fed to pigs without F18+E. coli challenge (NC) and 3 levels of MBB (0.0%, 0.1%, and 0.2%) in pigs challenged with F18+E. coli. On day 7 of the study, pigs in the challenged group were orally inoculated with F18+E. coli (1.5 × 1010 CFU). On days 7 and 21 post-challenge, pigs were euthanized to collect jejunal tissues and mucosa. Compared to the NC, 0.0% MBB increased (P < 0.05) relative abundance (RA) of Staphylococcus saprophyticus and reduced (P < 0.05) Streptococcus parasuis at days 7 and 21 post-challenge, respectively. Increasing levels of MBB decreased (linear: P < 0.05) RA of S. saprophyticus on day 7 post-challenge. Compared to the NC, 0.0% MBB increased (P < 0.05) jejunal NOD2 and IL-6 expression and decreased (P < 0.05) ZO-1 on day 7 post-challenge. Compared to the NC, 0.0% MBB decreased (P < 0.05) jejunal IL-6, IL-8, and TNF-α and increased (P < 0.05) IgG on day 21 post-challenge. Increasing levels of MBB increased OCLN (linear: P < 0.05) and ZO-1 (linear and quadratic: P < 0.05) on day 7 post-challenge and decreased toll-like receptor 4 (TLR4; linear and quadratic: P < 0.05). Compared to the NC, 0.0% MBB decreased (P < 0.05) Ki-67+ on day 7 post-challenge. Increasing levels of MBB increased (linear: P < 0.05) Ki-67+ on day 7 post-challenge and villus height (VH):CD on d 21 post-challenge. In the overall period, compared to the NC, 0.0% MBB decreased (P < 0.05) average daily gain. Increasing daily MBB intake linearly increased OCLN on day 7 and VH:CD on day 21, and reduced TLR4 and IL-8 on day 21 post-challenge, but exhibiting quadratic effects (P < 0.05) on ZO-1 (optimal at 0.12% of MBB), IgG (optimal at 0.14% of MBB), and G:F during days 7 to 20 and days 7 to 28 (optimal at 0.22% and 0.10% of MBB, respectively). In conclusion, F18+E. coli challenge negatively modulated the jejunal mucosal microbiota and reduced intestinal morphology and growth of nursery pigs. Supplementation of MBB at 0.10% to 0.14% provided optimal mitigation of the impacts of F18+E. coli challenge on humoral immunity, intestinal integrity, jejunal morphology, and feed efficiency of pigs.