The Role of ß-Mannanase (Hemicell) in Improving Poultry Productivity, Health and Environment

ABSTRACT The poultry nutritionists constantly attempt to identify and alleviate the factors responsible for adverse effects on nutrient utilization and production performance in avian species, which are necessary for successful productivity of poultry. Enhanced feed utilization can reduce levels of some nutrients in the diet with concomitant mitigation in nutrient excretion into the environment, reduction of eutrophication and acidification potentials of excreta. Commercial enzymes have been used to improve feed efficiency and utilization in poultry. Among many anti-nutritional factors, the existence of ß-mannans in poultry feed ingredients including soybean and other leguminous seeds has been associated with negative effects on nutrient digestibility and high intestinal viscosity that adversely affects innate immunity and microbial proliferation in poultry gut. The ß-mannanase (a commercial product named as Hemicell) can hydrolyze ß-mannan, an anti-nutritional fiber present in many poultry feed ingredients. Supplement of ß-mannanase to ß-mannan-rich diets may boost the population of intestinal beneficial bacteria, increase the digestibility of mannans, enhance the immunity, suppresses the growth of harmful intestinal bacteria, enhance the digestion and absorption of nutrients in intestinal tracts and reduce the environmental pollution due to poultry excreta. Supplementation of β-mannanase at the level of 200 and 400 mg/kg in poultry diets has positively improved blood glucose and anabolic hormone homeostasis, FCR, digestible energy, and digestible amino acids. This review describes the promising beneficial effects of β-mannanase, which may be used in the poultry feed industry for economic benefits. Another objective of this review is to explore the underlying mechanisms of ß-mannanase that can influence growth, digestion coefficients of nutrients, health and metabolism of nutrients in poultry birds and also the knowledge regarding the useful application of this feed enzyme in the commercial poultry feed industry.摘要 家禽营养学家始终致力于识别并缓解影响禽类营养利用与生产性能的各类不利因素，而这些性能是家禽实现高效生产的必要前提。提升饲料利用率可降低日粮中部分营养物质的添加量，同时降低营养物质向环境中的排泄量，减轻粪便的富营养化与酸化潜力。商用酶制剂已被用于改善家禽的饲料效率与营养利用率。在众多抗营养因子中，大豆及其他豆科籽实等家禽饲料原料中含有的β-甘露聚糖（β-mannan），会降低营养物质消化率并升高肠道黏度，进而对家禽肠道的先天免疫与微生物增殖产生不利影响。β-甘露聚糖酶（β-mannanase，商用商品名为Hemicell）可水解β-甘露聚糖——这种抗营养纤维广泛存在于多种家禽饲料原料中。在富含β-甘露聚糖的日粮中添加β-甘露聚糖酶，可促进肠道有益菌定植，提升甘露聚糖消化率，增强机体免疫功能，抑制有害肠道菌增殖，强化肠道内营养物质的消化与吸收，并降低家禽粪便造成的环境污染。当日粮中β-甘露聚糖酶添加量为200和400 mg/kg时，可有效改善家禽的血糖与合成代谢激素稳态、提升饲料转化率（Feed Conversion Ratio, FCR）、可消化能水平以及可消化氨基酸含量。本综述阐述了β-甘露聚糖酶颇具应用前景的有益功效，其可应用于家禽饲料行业以获取经济效益。本综述的另一目标，是探究β-甘露聚糖酶影响家禽生长性能、营养物质消化系数、机体健康与营养代谢的潜在作用机制，同时梳理该饲用酶制剂在商业家禽饲料行业中的有效应用相关研究进展。