优化饲料的整体消化率，以获取其全部营养价值

1.饲料酶：从难消化部分到整体饲料酶方法

深入了解植酸和膳食纤维等不可消化成分及其在家禽饲料中的相互作用，是获取外源酶全部价值的关键。为了估算酶制剂在动物饲料中的潜力，营养学家必须首先了解有多少营养成分未被消化并具有抗营养特性。由于外源酶的目的是将部分非消化成分释放为可消化的营养物质，因此了解非消化营养物质的数量有助于评估这种酶反应的潜力。事实证明，将几种外源酶视为一种独特的酶解决方案，可分解反营养成分并从中释放营养物质，是评估饲料消化率改善情况的最佳方法。这种观点被称为饲料酶方法。Feedase是指考虑整个饲料的整体酶解，从而提高所有营养物质的消化率，包括脂肪、淀粉、蛋白质、磷等......在这种新方法中，酶的作用与特定底物相关，但酶的作用与对营养物质（如脂肪、淀粉、蛋白质、磷）的间接作用相关，与酶的互补作用相关。

2.用多种碳水化合物酶提高饲料的总体消化率

为了证明多元碳水化合物酶（Rovabio® Advance®）的功效，法国 Commentry 的安迪苏 实验农场采用欧洲参考方法，对 13-22 日龄的 Ross PM3 雄性肉鸡进行了消化率试验，试验采用自由采食法，并收集了 3 天的总排泄物（Bourdillon 等人，1990 年）。从 0 天到 12 天，给鸟喂以小麦和大豆为基础的普通开食料，然后喂以简单成分（小麦和豆粕）或更复杂成分（小麦、大麦、黑麦、小麦 DDGS、豆粕、葵花籽粕、菜籽粕）的生长饲料。无论日粮成分如何，添加酶都能显著提高能量利用率和几种营养物质的消化率（表 1）。

*p<0.05¹ Rovabio® Advance L2
Ref: Cozannet et al. 2017, Poultry Science

This improvement was more important for the complex diets than for the simple diet. The improvement observed on energy utilization and digestibility of nutrients was related with arabinose xylose content 69.2 vs. 59.5 g/kg for complex and simple diets, respectively. To further validate the concept of global feed digestibility, the effect of Rovabio® Advance was evaluated in a standard wheat-based diet diluted with 3% of sand (Cozannet et al. 2018, Journal of Poultry Science). This study investigated the effect of Rovabio® Advance® on energy and ileal amino acid (AA) digestibility of a complete wheat/soybean-based diet in broilers. The commercial control diet was compared with a 3% nutrient-diluted version using silica as inert diluent. Digestibility of dry matter (DM), AA and gross energy (GE) were determined by analysis of feed, excreta and digesta. Ross PM3 broiler chicks were studied during the grower period and diet dilution did not increase feed intake. Fecal energy digestibility was similar (approximating 73%) for diets without enzymes (P = 0.99). However, apparent metabolizable energy (AME) content was significantly lower in the diluted versus control diet. Rovabio® Advance improved energy utilization (P < 0.001), leading to an increase of AME content for both the diluted and standard diets. AME content of diluted diet with Rovabio® Advance was similar to that of the standard diet without enzymes (P = 0.98), demonstrating the ability of this enzyme to fully compensate the 3% nutrient dilution (Figure 1).

At ileal level, AA digestibility was around 75% across all treatments. The addition of the multi-carbohydrase increased AA digestibility by an average of 3.3% (P<0.001, Figure 2). Rovabio® Advance® restored nutrient availability when the nutrient content of a diet was diluted by 3%. This study highlights the importance of considering the entire nutrient matrix when global enzyme solutions are supplemented to diets.

3.用多种碳水化合物酶和植酸酶提高饲料的总体消化率

为了评估一种含有多种碳水化合物酶（特异性木聚糖酶、β-葡聚糖酶和阿拉伯呋喃糖苷酶）和最佳剂量植酸酶（1000 FTU/公斤饲料）的复合酶的效果，这种酶被称为 Rovabio®Advance Phy在法国 Zootests 进行了一项肉鸡栏试验。与阳性对照相比，试验日粮的配方规格较低（表 2）。

ME was reduced by 3, 4 or 5% and dAA by 3, 4.5 or 6%, in 3 different treatments, along with a fixed reduction of 0.174% units avP and 0.157% units Ca. These three groups were compared with or without the multi-carbohydrase phytase complex (MCPC). A positive control was raised in parallel. All treatments used a corn wheat-soybean based diets. Growth performance, carcass characteristics and bone mineralization were measured, and results statistically compared. The reduction of ME, dAA, avP and Ca in the diet significantly reduced the body weight gain and increased FCR (P < 0.0001; Figure 3) similarly for the 3 NC diets; with no effect on feed intake.

在 42 日龄时，无论日粮配方如何调整，添加酶制剂后这些性能标准都能恢复到阳性对照组的水平。该试验表明，在肉鸡日粮中添加 Rovabio®Advance Phy 可显著降低肉鸡的规格，最高可降低 ME 5%、dAA 6%、avP 0.174% 单位和 Ca 0.157% 单位。研究表明，酶制剂组合可降低饲料成本。

使用 替代成分由于基质数量较多，它们对酶非常敏感，因此使用它们似乎是降低成本的一种有前途的策略。它们的低消化率可以通过添加酶来弥补，而且可以提供不可忽略的营养成分。在含有 6% 葵花籽粕的玉米-大豆-小麦日粮中，Rovabio®Advance Phy 可以节省多达 27 欧元/吨的饲料，而不会对动物的生产性能产生任何影响。

作者：Pierre Cozannet 博士和安迪苏饲料消化专家 Maamer Jlali 博士

参考资料 ：

Jlali 等人（2020 年）。评估肉鸡日粮中的多淀粉酶和植酸酶复合物的能量、氨基酸、可利用磷和钙含量。家畜科学 241 (2020) 104227。

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