Department of Poultry Science, University of Georgia, Athens, GA, USA.
Department of Poultry Science, North Carolina State University, Raleigh, NC, USA.
Poult Sci. 2021 Sep;100(9):101312. doi: 10.1016/j.psj.2021.101312. Epub 2021 Jun 5.
β-mannan is a nonstarch polysaccharide found in hulled and dehulled soybeans that can survive drying-toasting phase of processing soybeans and have antinutritive effects in poultry. β-mannanase is an active enzyme (endohydrolase) that can hydrolyze β-mannan to reduce its antinutritional effects. Two experiments were conducted to evaluate the effects of β-mannanase supplementation in low energy/protein diets on egg production, egg quality, and apparent ileal digestibility of the dry matter (DM), crude protein (CP), and amino acids in 21-week-old Single Comb White Leghorn hens (Hy-Line W-36). A total of 192 hens (8 replicates of 6 hens per treatment) for a production study (Exp. 1) and a total of 64 hens (8 replicates of 2 hens per treatment) for a digestibility study (Exp. 2) were randomly allocated to 4 experimental treatments in a 2 × 2 factorial arrangement. Four dietary treatments were control (CS) based on corn and 44% CP soybean meal (ME: 2,850 kcal/kg CP: 18.5%) and CS-low energy/protein (CSL) (ME: 2,750 kcal/kg CP: 17.5%), with or without 0.05% β-mannanase enzyme. Hens were fed the experimental diets for 14 d for the digestibility study and 8 wk for the production study. Hen-day egg production (HDEP), weekly feed intake, FCR, and biweekly egg quality parameters were measured. Significant interaction on feed intake (P < 0.01) was observed between energy/protein and enzyme. At 3, 6 and 8 wk, the feed intake and FCR of CSL with enzyme were significantly lower than those of CSL without enzymes. The main effects indicated that birds fed diets without inclusion of β-mannanase had higher feed intake than those fed diets with enzymes at 4, 7, and 8 wk. The inclusion of β-mannanase significantly increased (P < 0.05) HDEP at 2, 3, 5, and 7 wk. However, there was no significant effect of nutrient density or enzyme supplementation on egg quality parameters. The digestibility study showed that the inclusion of β-mannanase significantly improved (P < 0.01) apparent ileal digestibility of lysine, histidine and tryptophan in the diet. The results of these experiments indicate that supplementation of β-mannanase could reduce the feed intake and FCR and improve HDEP and apparent ileal digestibility of key amino acids in corn/soy diets fed to laying hens.
β-甘露聚糖是一种存在于带壳和去壳大豆中的非淀粉多糖，能够在大豆的干燥-烘焙加工阶段存活下来，并对家禽产生抗营养作用。β-甘露聚糖酶是一种具有活性的酶（内切水解酶），可以水解β-甘露聚糖，从而降低其抗营养作用。本试验旨在评估低能量/蛋白质日粮中添加β-甘露聚糖酶对 21 周龄海兰白来航鸡产蛋性能、蛋品质和干物质（DM）、粗蛋白（CP）及氨基酸表观回肠消化率的影响。试验一选用 192 只母鸡（每处理 8 个重复，每个重复 6 只鸡）进行产蛋性能研究，试验二选用 64 只母鸡（每处理 8 个重复，每个重复 2 只鸡）进行消化率研究。采用 2×2 因子完全随机设计，将母鸡随机分为 4 个处理，分别为对照组（基于玉米和 44% CP 豆粕，代谢能为 2850 kcal/kg，CP 为 18.5%）和低能量/蛋白质对照组（基于玉米和 44% CP 豆粕，代谢能为 2750 kcal/kg，CP 为 17.5%），日粮中添加或不添加 0.05%β-甘露聚糖酶。母鸡分别饲喂试验日粮 14 d 进行消化率试验，8 wk 进行产蛋性能试验。试验期间记录母鸡的产蛋率、每周采食量、料蛋比和两周一次的蛋品质。结果表明，能量/蛋白质与酶存在显著的互作效应（P＜0.01）。在 3、6 和 8 周时，添加酶的低能量/蛋白质组的采食量和料蛋比显著低于未添加酶的低能量/蛋白质组。主要效应表明，在第 4、7 和 8 周时，未添加β-甘露聚糖酶的日粮组的采食量高于添加酶的日粮组。添加β-甘露聚糖酶可显著提高（P＜0.05）第 2、3、5 和 7 周的产蛋率。然而，日粮养分密度或酶添加对蛋品质参数没有显著影响。消化率试验结果表明，添加β-甘露聚糖酶可显著提高（P＜0.01）日粮中赖氨酸、组氨酸和色氨酸的表观回肠消化率。这些试验结果表明，在玉米/豆粕日粮中添加β-甘露聚糖酶可以降低采食量和料蛋比，提高产蛋率和关键氨基酸的表观回肠消化率。
