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

提高饲料转化效率，同时最大限度地减少对环境的不利影响，是安大略省和加拿大养猪业改善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作为生长促进剂的饲料抗菌剂的情况下。已有文献表明，碱性磷酸酶(AP)对于消除肠道环境中病原菌的内毒素，从而维持猪的肠道功能是必不可少的。然而，断奶仔猪肠道内源性AP活性不足以发挥这样的生物学作用。因此，需要开发外源AP作为肠道改良剂来提高猪的肠道消化功能，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的生物发生和粪便中挥发性气味化合物的排泄，如臭味。在猪营养中使用外源AP的概念已有报道，但外源AP作为新型外源饲料酶和肠道改良剂的商业应用尚未得到政府的批准和建立。因此，这项拟议的研究项目是：i)研究日粮中添加最佳水平的外源AP对提高加拿大东部和西部典型猪日粮中断奶仔猪整体生长性能和养分消化利用的影响；以及ii)研究饲喂最佳水平的外源AP对生长肥育猪的整体生长性能、养分消化利用和挥发性气味化合物排泄的影响。通过实施这个拟议的项目，加拿大猪肉行业将通过促进外源饲料AP作为一种新出现的有效肠道改良剂的商业化和应用来实现预期的好处，以改善整体生长性能、饲料转化率和利润率；并减少来自猪的粪便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.