Nonruminant Nutrition Symposium: Models for Disease × Nutrition Evaluation and the Impact of Nutrition on Health, Disease, and/or Recovery

In sick animals, the anorectic response is part of a series of complex but coordinated physiological and behavioral adaptations to recover from a disease episode. Thus, it is not surprising that animals appear to have a physiological preference for using endogenous nutrients over dietary supply, particularly during acute immune activation. Because survival and recovery have utmost nutritional priority, sick animals usually exhibit reduced growth performance, and nutritionists commonly rely on non-productive outcomes to determine the benefits of nutritional interventions. The effect supplementing diets with several nutrients and feed additives on intestinal health have been evaluated in various animal models using a wide variety of single immunological challenges. Our laboratory is currently using both Salmonellaand lipopolysaccharidechallenged pigs to determine how immune activation alters nutrient utilization as well as the contribution of prebiotic supplementation on intestinal health and recovery from an enteric infection. Results from our studies indicate increased amino acid catabolism during acute experimental sepsis and impaired amino acid digestibility during a bacterial infection of the gastrointestinal tract. Further, inclusion of a yeastderived prebiotic in the diet of Salmonella-challenged pigs appears to improve fecal beneficial bacteria and intestinal morphology, which were associated with an enhanced growth performance during the recovery phase. The appropriateness of the animal model and the immune challenge, however, must be carefully considered when making intestinal health inferences of nutrients and supplements to be implemented in commercial animal production systems, which are usually affected by diseases of complex etiology.