Understanding the Health Benefits of Feeding Treated Wheat Straw for Weanling Pigs

Veronica I Polniak, Jaron Lewton, Medhat A Michael, Kyan M Thelen, Adam J Moeser, Dale W Rozeboom

Two experiments were conducted to understand the growth and health benefits of including treated wheat straw in weanling pig diets. The first experiment evaluated feeding treated versus untreated wheat straw on young pig growth performance and localized immunological markers. One hundred and ninety-two (PIC 359 x Yorkshire) pigs were weaned at 26.8 ± 1.1 d old (8.3 ± 1.1 kg) and randomly allotted to 24 pens with 8 pigs per pen. Three dietary treatments were fed over a 28-d period, control (CON), control plus 5% untreated wheat straw (UWS), and control plus 5% treated wheat straw (TWS). Diets were formulated to meet or exceed all nutrient requirements of NRC, 2012. Growth performance data was recorded on a weekly basis. One pig per pen (equal number of males and females) was randomly selected for sacrifice and sample collection on d 28. The second experiment evaluated the impact of 5% dietary TWS on the local and systemic health of nursery pigs experiencing a vaccination-induced immune challenge. Twenty barrows (PIC 800 x Yorkshire) were weaned at 27.7 ± 0.75 d (8.6 ± 1.2 kg) and assigned to four pens, with 5 pigs per pen. A heavy and light-weight pen for each treatment (CON and TWS) resulted. All pigs were sacrificed for sample collection on d 42. In both experiments, before euthanasia, blood was collected to assess plasma immunoglobulin A (IgA) and intestinal fatty acid binding protein (iFABP) concentration. Upon sacrifice, segments of the distal ileum and ascending colon were removed to collect mucosal scrapings for the analysis of localized immunological markers interleukin (IL) 6, IL-10, IL-12, and tumor necrosis factor-alpha (TNF-α). In experiment one, overall ADG and ADFI were similar among treatments. Gain-to-feed ratio of TWS pigs was greater (P < 0.05) than that of UWS pigs and tended to be greater (P = 0.07) than that of CON pigs (0.70, 0.67, and 0.68, respectively; SEM = 0.01). Both straw treatments decreased the expression of ileal and colonic mucosa IL-6, in addition with less expression of ileal IL-12. Plasma IgA concentrations in UWS pigs were greater than those in CON and TWS pigs (P < 0.05). In experiment two, TWS pigs had greater gene expression of colonic TNF-α and IL-6 (P < 0.05). Ileal gene or protein expression of markers did not differ, nor did amounts of plasma IgA or iFABP. Overall, feeding 5% treated wheat straw in the nursery pig diet does not negatively impact growth and results in increased feed efficiency. Nursery diets with 5% treated wheat straw can impact the expression of immune markers in the gut, but the question of how this is related to performance and overall health needs further elucidation.