Abstract While conventional fiber sources in nursery diets are well characterized, the effects of alternative fiber ingredients on the physiological and behavioral responses of pigs after weaning and transport stress remain unclear. The study objective was to evaluate the impact of replacing corn with alternative fiber sources on intestinal, hormonal, behavioral, and metabolic status following weaning and transport. We hypothesized that replacing corn with alternative fiber sources would improve intestinal morphology and behavioral responses without impacting post-absorptive metabolic biomarkers. Mixed-sex piglets N = 216; Duroc (Landrace x Yorkshire) were weaned and transported for 12 h to simulate commercial conditions. Following transport, pigs were allotted by sex and blocked by weaning weight (6.5 ± 0.1 kg) into pens that were assigned one of two dietary treatments. Pens were fed either a corn-soybean meal-based diet (CON; n = 12 pens/treatment; 9 pigs/pen) or a fiber blend (FIBER; n = 12 pens/treatment; 9 pigs/pen) that replaced corn with equal parts sugar beet pulp and alfalfa meal at a rate of 5.0, 7.5, 10.0, and 12.5% in diet phases 1-4, respectively, with additional fat added at each phase (1.0, 1.5, 2.0, and 2.5%, respectively) to ensure diets were isocaloric. Diets were provided ad libitum with free access to water. One pig per pen (n = 12/treatment) was selected for blood sampling on d 1 pre-weaning, and d 7, 14, 21, 28, and 35 post-weaning after a standardized 2 h fast. Plasma was analyzed for insulin, cortisol, non-esterified fatty acids (NEFA), and glucose. At d 7 and 35, one pig per pen (n = 24 pigs per treatment total) was sampled for jejunum and ileum villi, crypt, and villus:crypt estimates, and cecum and colon to determine crypt values. All pigs were video-recorded on d 1, 2, 3, and 36 post-weaning to evaluate feeding, drinking, and pen-level aggression. Behavior data were separated into AM (0900–1100 h) and PM (1400–1600 h) periods. Pen was considered the experimental unit with room and weight block as random effects. Overall, NEFA levels were greater (P 0.05; 27.5%) for FIBER versus CON pigs. At d 7, jejunal villus height tended to be reduced (P 0.10; 17.2%) and jejunal villus:crypt was reduced (P 0.05; 23.9%) in the FIBER versus the CON pigs. FIBER pigs tended to have greater AM aggression (P 0.10; 20.1%) but lower PM aggression (P 0.10; 12.4%) compared to CON pigs. No other treatment-related differences (P 0.10) were observed. In conclusion, the FIBER treatment had moderate negative effects on jejunal morphology at d 7 and increased circulating NEFA levels, likely due to greater dietary fat inclusion. These observations suggest a transient gastrointestinal response that was resolved through physiological adaptation to fiber inclusion.
Sullivan et al. (Wed,) studied this question.