Exogenous alkaline phosphatases in improving growth, efficiency of nutrient utilization and gut fermentation in pigs

提高饲料转化效率，同时尽量减少对环境的有害影响，是提高安大略省和加拿大养猪业有限利润率的主要方向，特别是在加拿大商业断奶猪日粮中禁止使用饲料抗菌剂作为生长促进剂的情况下。有充分的文献证明，碱性磷酸酶（AP）对肠道环境中病原菌的内毒素解毒至关重要，从而维持猪的肠道功能。然而，断奶仔猪肠道内源AP活性不足以发挥这一生物学作用。因此，需要开发外源添加AP作为肠道调节剂，以增强猪的肠道消化功能，改善肠道发酵，提高猪的生长性能。此外，外源饲料AP可以调节肠道微生物平衡，从而潜在地调节和减少猪体内挥发性恶臭化合物（如粪臭素）的生物发生和粪便排泄。在猪营养中使用外源添加AP的概念已被报道；然而，外源饲料AP作为新型外源饲料酶和肠道调节剂的商业应用尚未得到政府的建立和批准。因此，本研究拟开展的研究项目为：i)研究饲粮中添加最佳水平外源AP对提高典型加拿大东、西部猪日粮断奶仔猪整体生长性能和营养物质消化利用的影响；ii)研究饲喂最佳外源AP水平对饲喂典型加拿大东部和西部猪日粮的生长肥育猪的整体生长性能、营养物质消化利用和挥发性致臭化合物粪便排泄的影响。通过实施这一拟议项目，将促进外源饲料AP作为一种新出现的有效肠道调节剂的商业化和应用，以提高整体生长性能、饲料转化率和利润率，从而实现对加拿大猪肉行业的预期效益；并减少猪粪便中挥发性气味化合物对环境的负面影响。

Improving feed conversion efficiency while minimizing detrimental impacts on the environment is a major direction to improve limited profit margins in Ontario and the Canadian swine industry particularly when feed antimicrobials as growth promoters have now been banned in commercial weanling swine diets in Canada. It has been well documented that alkaline phosphatases (AP) are essential to detoxify endotoxins from pathogenic bacteria in the gut environment, thus maintaining gut functions in pigs. However, weanling pig gut endogenous AP activities are insufficient in playing such biological roles. Thus, exogenous supplemental AP need to be developed as gut modifiers to enhance gut digestive functions, improve gut fermentation, and increase growth performances in swine feeding. Furthermore, exogenous feed AP can modulate gut microbial balancing, thus potentially modulate and reduce biogenesis and fecal excretion of volatile odor-causing compounds such as skatole in pigs. The concept of using exogenous supplemental AP in swine nutrition has been reported; however, commercial applications of exogenous feed AP as novel exogenous feed enzymes and gut modifiers are yet to be established and approved by the government. Therefore, this proposed research project is: i) to investigate effects of dietary supplementation of optimal levels of exogenous feed AP on improving overall growth performances and digestive utilization of nutrients in weanling pigs fed typical Eastern and Western Canadian swine diets; and ii) to examine effects of feeding optimal levels of exogenous feed AP on overall growth performances, digestive utilization of nutrients and fecal excretion of volatile odor-causing compounds in growing-finishing pigs fed on typical Eastern and Western Canadian swine diets, respectively. Anticipated benefits for Canadian pork industry through conducting this proposed project will be achieved through facilitating the commercialization and applications of exogenous feed AP as a newly emerged effective gut modifier to improve overall growth performances, feed conversion and profit margins; and to reduce the negative environmental impacts of the fecal volatile odor-causing compounds from swine.