330 - Developing a Leaky Gut Model in Growing Holstein Heifers Using Feed Restriction Followed by Alimentation to a High Concentrate Diet

Abstract: The objective of this study was to determine if feed restriction (FR) followed by feeding a high concentrate (HC) diet would induce leaky gut syndrome (LGS) in cattle. Changes in circulatory and fecal biomarkers were utilized to assess LGS. Individually penned Holstein heifers (n=16; BW=343.2 ± 3.2 kg) were used in a completely randomized design with animal as the experimental unit. Cattle were fed a forage-based diet (71.0% hay, 12.0% cracked corn, 17.0% DDGS) twice daily ad libitum from day 0-14; from day 15-17, the daily ration was restricted by 60%. One of two HC diets (n=8 each) were fed ad libitum from day 18-30: HC75=17.0% hay, 70.0% cracked corn, 13.0% DDGS; HC65=26.5% hay, 60.0% cracked corn, 13.5% DDGS. Blood and fecal samples were collected prior to a.m. feed delivery (d -1, 0, 14, 15, 18, 20, 24, 30) and analyzed for serum amyloid-A (SAA), haptoglobin (Hp), lipopolysaccharide-binding protein (LBP), fecal lactoferrin, and fecal pH. Variables were analyzed using a mixed model with repeated measures; study day, treatment and the interaction were fixed effects. Following FR, SAA was significantly increased from day 14 to 24 (27,406.20 ± 8,917.00 ng/mL; P = 0.046). Similarly, LBP was significantly increased from day 14 to 20 (353.71 ± 44.40 ng/mL; P < 0.0001). Fecal lactoferrin increased significantly from day 18 to 20 (293.9 ± 57.54 ng/g; P = 0.0001). Fecal pH decreased significantly (1.48 ± 0.09; P < 0.0001) from day 14 to 30 and from day 18 to 30 (1.57 ± 0.08; P < 0.0001) reaching its nadir on day 30 (5.35). No meaningful changes were observed for Hp. Based on these data, FR followed by feeding a HC diet effectively experimentally induced LGS as indicated by observed changes in SAA, LBP, fecal lactoferrin and fecal pH.