Effect of feed restriction on outcomes of swine influenza virus infection in pigs pre-infected with Mycoplasam Hyopneumoniae

European avian-like swine H1N1 was identified as one major pathogen of the porcine respiratory disease complex (PRDC) together with Mycoplasma hyopneumoniae (Mhp), and experimental pre-infection of pigs with Mhp was shown to increase the severity of a subsequent infection with H1N1. In order to evaluate novel control strategies towards such a multifactorial disease, we studied the impact of a moderate feed restriction on the ability of Mhp/H1N1 co-inoculated animals to resist the infection, as efficiency of inflammatory responses might be influenced by the nutritional status of the animal. Two groups of 8 SPF pigs were intra-tracheally inoculated with Mhp and H1N1 21 days apart. One group was fed ad libitum whereas the other one was applied a 40% feed restriction one week before H1N1 infection. Two similar mock-inoculated groups of 4 pigs each were included. All pigs were fitted with a jugular catheter. Three days post-H1N1 infection, the same amount of a standardized meal was given to all animals and kinetics of blood samples were performed during 4 hours for measuring plasma postprandial nutrient concentrations. Pigs were slaughtered 7 days post-H1N1 infection. Clinical signs were observed throughout the study and pathogens were detected in nasal swabs and lung tissues. Feed restriction had no effect on pathogen excretion and dissemination in infected host or on pulmonary lesions. However, feed- restricted pigs presented a shorter hyperthermia as well as a positive mean weight gain over the 3 first days following H1N1 infection as compared to animals fed ad libitum which lost weight during that period. Both infection and feed restriction modified postprandial kinetics of glucose and amino acid concentrations showing dramatic changes in nutrient metabolism. Our results indicated that feeding practices could be a strategy to prepare animals to overcome an influenza infection, especially in a PRDC context