Effect of Feed Restriction on Performance and Postprandial Nutrient Metabolism in Pigs Co-Infected with Mycoplasma hyopneumoniae and Swine Influenza Virus

As nutritional status and inflammation are strongly connected, feeding and nutritional strategies could be effective to improve the ability of pigs to cope with disease. The aims of this study were to investigate the impact of a feed restriction on the ability of pigs to resist and be tolerant to a coinfection with Mycoplasma hyopneumoniae (Mhp) and the European H1N1 swine influenza virus, and the consequences for nutrient metabolism, with a focus on amino acids. Two groups of specific pathogen-free pigs were inoculated with Mhp and H1N1 21 days apart. One group was fed ad libitum, the other group was subjected to a two-week 40% feed restriction starting one week before H1N1 infection. The two respective mock control groups were included. Three days post-H1N1 infection, 200 g of feed was given to pigs previously fasted overnight and serial blood samples were taken over 4 hours to measure plasma nutrient concentrations. Throughout the study, clinical signs were observed and pathogens were detected in nasal swabs and lung tissues. Feed-restricted pigs presented shorter hyperthermia and a positive mean weight gain over the 3 days post-H1N1 infection whereas animals fed ad libitum lost weight. Both infection and feed restriction reduced postprandial glucose concentrations, indicating changes in glucose metabolism. Post-prandial plasma concentrations of the essential amino acids histidine, arginine and threonine were lower in co-infected pigs suggesting a greater use of those amino acids for metabolic purposes associated with the immune response. Altogether, these results indicate that modifying feeding practices could help to prepare animals to overcome an influenza infection. Connections with metabolism changes are discussed.

鉴于营养状态与炎症反应密切相关，饲喂策略与营养干预手段可有效提升猪只的抗病能力。本研究旨在探究限饲对猪只抵抗和耐受猪肺炎支原体（Mycoplasma hyopneumoniae, Mhp）与欧洲H1N1猪流感病毒混合感染的能力的影响，以及其对营养代谢（重点为氨基酸代谢）的影响。本实验选取两群无特定病原体（specific pathogen-free, SPF）猪只，分21天先后接种Mhp与H1N1病毒。其中一组自由采食，另一组在H1N1感染前1周开始接受为期2周的40%限饲方案；同时设置对应的两组空白对照组。在H1N1感染后第3天，对前一晚禁食的猪只饲喂200g饲料，并在4小时内连续采集血液样本以检测血浆营养物质浓度。实验全程观察猪只临床症状，并通过鼻拭子与肺组织样本检测病原体。限饲组猪只在H1N1感染后3天内发热时长更短，且平均体重呈正增长；而自由采食组猪只则出现体重下降。感染与限饲均会降低餐后血糖浓度，提示葡萄糖代谢发生改变。混合感染组猪只的餐后血浆必需氨基酸组氨酸、精氨酸与苏氨酸浓度更低，表明这些氨基酸被更多用于与免疫应答相关的代谢过程。综合以上结果，本研究表明优化饲喂方案可帮助猪只抵御流感感染；本文还讨论了该结果与代谢改变之间的关联。