在波動的市場中如何達到最佳的飼料性能?

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　　正確使用酶和植酸鹽,增加生產，節省飼料成本。
　　盡管原料成本上漲，波動，但肉雞養殖者必須要依據生長和均勻度的雙重要求來滿足性能目標。
　　在肉雞的生產周期中，許多因素會影響它們實現飼料潛在的代謝能（ME）全部發揮。日糧和環境中的變化以及遺傳學都發揮作用。然而，家禽養殖者的主要挑戰是在飼料消化率和它對動物生產力的影響。
　　盡管原料成本在上漲和波動，但生產者必須依據動物生長和雞群均勻度來繼續滿足性能目標。這些挑戰可在替代原料和副產品使用大幅上升的情況中看到，替代品如DDGS，米糠，菜籽粕，雙低油菜籽粕，葵花粕，棕櫚仁粕和麥糠。
　　在飼料配方中添加這些替代品會產生一系列的挑戰：維持營養的充足以及抗營養因子的處理。與更多傳統的飼料原料相比，這些材料的挑戰主要是它們的組成，一般是淀粉和蛋白含量低，而且有更高水平的抗營養因子如阿拉伯木聚糖和植酸。
　　抗營養因子的問題
　　不溶性阿拉伯木聚糖是植物細胞壁的結構成分,單胃動物對它們的消化率很差。不溶性阿拉伯木聚糖含量的提高將會產生屏障，阻礙內源性酶儲存蛋白質、淀粉和脂肪的功能。它們也一直與增加食糜粘度，減慢運輸時間，降低營養物質消化率和腸道菌群的不良變化有關系。結合這些特點產生負面影響動物的生產性能和腸道健康的影響。這些不良效應會給動物生產性能和腸道健康帶來負面影響。
　　植酸鹽是另外一種強大的抗營養物質，它與礦物質，淀粉和蛋白質結合，提高它們抵抗消化的能力。這會增加回腸氨基酸回流率，反過來就會為病原體生長提供基質。
　　植酸未水解也會為環境帶來負擔，因為它會導致更大的磷污染和較高的糞便管理和法律規范成本。為了說明挑戰的深度，我們知道42天齡的肉雞日糧中大約45%的磷都從糞便中排出。如果我們認為僅僅在美國就有6000萬的肉雞飼養者，每年生產90億肉雞，累計磷的排泄量達到了驚人的115,000噸/年。減少美國肉雞磷的排泄對環境的影響是相當大的。
　　處理變化
　　栽培方法和收割條件會改變作物的成分含量, 反過來也會相似地影響消化率，性能和環境
　　栽培方法和收割條件會改變作物的成分含量, 反過來也會相似地影響消化率，性能和環境。以玉米為例，它是全球最常見的飼料糧，但是其飼料價值是公認的量值，有時候僅僅是粘性可變，如小麥。
　　從簡單的玉米-大豆型日糧演變到復雜的，包含了各種替代原料，以此降低飼料成本，這對動物消化的日糧版塊產生了重大的影響。
　　例如，添加更多蛋白和能量源會使粗纖維（NDF,ADF和阿拉伯木聚糖酶）以及植酸含量，同時降低日糧中的淀粉含量?？上被?，是日糧中氨基酸的一部分，也會被降低。為了在每千克日糧成本降低時維持動物的性能，有必要克服這一結合效應造成的單個營養挑戰。
　　解決方案取決于酶
　　傳統中外源性酶可以為相對簡單的日糧提供價值，它們可通過增加營養消化率，同時抵抗原料的變異性來改善動物的性能和均勻性。隨著日糧變得越來越復雜和質量呈現多樣性，人們普遍承認，酶的使用變得更加寶貴。
　　植酸酶提供了一種消除植酸鹽抗營養作用，提高其消化率的相對便宜，經濟實惠的方式，這也通過減少骨骼問題來改善了動物的福利。最新的巴提奧桿菌菌植酸酶可提供超過大腸桿菌當量的額外好處，包括：在進入消化道前期更高的活力，最小化植酸鹽的抗營養作用，最大化營養消化吸收的活力時間。使用傳統和新生代植酸酶的好處是降低了糞便中磷的排泄。
　　酶，植酸酶組合產生利益
　　糖酶和適量的植酸酶結合也可從根本上改善復雜的日糧性能，減少整體生產成本。
　　如果我們查看一下，例如，將木聚糖酶，淀粉酶和蛋白酶與植酸酶的頂部結合，其效應是驚人的：
　　·木聚糖酶 (X) 可分解非淀粉多糖(NSPs)如日糧中可溶性和不溶性的阿拉伯糖基木聚糖，降低有粘性谷物如小麥的食糜粘度，釋放先前被阻礙的營養物質。
　　·淀粉酶 (A) 提高了淀粉的水解，改善了消化率，補充了內源性淀粉酶的分泌。
　　·蛋白酶通過水解儲存的和結構蛋白，打破蛋白質和日糧中淀粉以及纖維的結合，提高了蛋白質消化率。此外，它作用于日糧中的抗營養因子如儲存在豆粕和其他植物蛋白中的胰蛋白酶抑制劑和凝集素。
　　使用這些酶結合標準計量的巴提奧桿菌植酸酶，養殖者可實現一致的飼料質量和體重/熱量轉換，每百萬家禽可節省$80,000到$100,000的成本。
　　觀察外源性酶組合（如木聚糖酶，淀粉酶和蛋白酶）和其他飼料添加劑如何與新生代生物有效植酸酶作用，確保性能和成本可在波動的市場行情中創造利益，這將是很重要的。
　　兩位作者都是資深的動物營養學家。
　　英文發表在2013年11月的 Feed Management雜志上。
　　譯者：IRIS
　How to achieve optimum feed performance in a volatile market
　　在反復無常的市場中如何達到最佳的飼料性能?
　　日期: 2013-10-14
　　作者: Duke Barnard 和Luis Romero, Danisco動物營養公司


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　　英文原文：During the production cycle of a broiler, many factors influence a bird's ability to achieve the full metabolizable energy (ME) potential of the feed. Changes in diet and environment -- as well as its genetics -- can play a role. However, poultry producers' main challenge is the variance in feed digestibility and its impact on animal productivity.

　　Producers must continue to meet performance objectives, in terms of both growth and flock uniformity, despite increases and volatility in raw material costs (see Figure 1). This challenge has seen an increase in the use of alternative ingredients and byproducts in poultry feed such as DDGS, rice bran, rapeseed meal, canola meal, sunflower meal, palm kernel meal and wheat pollard.

　　Inclusion of these alternative raw materials in feed formulations introduced a complete set of challenges: maintaining the nutrient specification of the diet and managing anti-nutrient factors. Compared to more traditional feed ingredients, the challenges of these materials are highlighted by their composition as they tend to be lower in both starch and protein quality and have higher levels of anti-nutrient factors, e.g. arabinoxylans and phytate.

　　Problems with anti-nutrients

　　Insoluble arabinoxylans are structural components of the cell walls of plant that are poorly digested by monogastric animals. Increased levels insoluble arabinoxylans produce a barrier for endogenous enzyme activity on storage proteins, starch and fat. They have also been associated with increased digesta viscosity, slower transit time, lower nutrient digestibility and undesirable shifts in gut microbiota. The combined effects of these characteristics negatively impact animal performance and gut health.

　　Phytate is another potent anti-nutrient. It binds minerals, starch and proteins, increasing their resistance to digestion. This can lead to increased ileal amino acid flow which, in turn, provides substrates that can encourage pathogen growth.

　　Failing to hydrolyse phytate also carries an environmental burden as it leads to a greater threat of phosphorous pollution and higher manure management and legislative compliance costs. To exemplify the extent of the challenge, roughly 45 percent of all phosphorous consumed in the normal diet of a 42-day-old broiler is excreted in manure. If we consider that the United States alone produces 60 million broiler breeders and 9 billion broilers every year, the cumulative phosphorus excretion reaches a staggering 115,000 metric tons/year. The environmental impact of reducing phosphorous for for U.S. broilers is considerable.

　　Cultivation methods and harvest conditions can produce varying feed substrate levels, which in turn lead to similar digestibility, performance and environmental issues. Corn, for example, is the most common feed grain used globally, but its feed value is universally recognized as being variable -- sometimes just as variable as viscous grains such as wheat.

　　Moving from simple corn-soy based diets to more complex ones, which include a variety of alternative raw materials to reduce feed costs, has a significant effect on the dietary substrates available for digestion by the animal.

　　For example, the inclusion of a wider variety of protein and energy sources produces a corresponding increase in fiber (NDF, ADF and arabinoxylans) and phytate levels and decreases in starch in the diet (see Figure 2). Digestible amino acids, expressed as a proportion of total amino acids in the diet, also decreases. This combination of effects creates unique nutritional challenges that need to be overcome in order for animal performance to be maintained while reducing costs per kg gain.

　　The solution lies with enzymes

　　Exogenous enzymes have traditionally offered value in relatively simple diets. They improve animal performance and uniformity by increasing nutrient digestibility while counteracting variability in raw materials. As diets become increasingly complex and the quality more variable, it is generally acknowledged that enzyme usage becomes even more valuable.

　　Phytase offers a relatively cheap, affordable way to eliminate the anti-nutritive effect of phytate and maximize its digestibility, which also improves animal welfare by reducing the risk of skeletal problems. The latest Buttiauxella-based phytase offers additional benefits over E. Coli equivalents, including: much higher activity earlier in the digestive tract, minimization of the anti-nutrient effects of phytate and maximization of the time available for nutrient digestion and absorption. An added benefit of using both traditional and new generation phytases is their ability to reduce phosphorus in manure.

　　Enzyme, phytase combination produce benefits

　　The combination of carbohydrase enzymes with the right amount of phytase can also radically improve complex diet performance and slash overall production costs.

　　If we look, for example, at combining xylanase, amylase and protease enzymes on top of phytase, the results are dramatic:

　　Xylanase (X) breaks down the non-starch polysaccharides (NSPs) such as soluble and insoluble arabinoxylans in the feed reducing digesta viscosity in viscous grains such as wheat and releasing previously trapped nutrients.

　　Amylase (A) increases the hydrolysis of starch improving its digestibility, and complements the secretion of endogenous amylases.

　　Protease increases protein digestibility by hydrolysis of storage and structural proteins, and disrupts interactions of proteins with starch and fiber in the diet. Additionally, it targets other anti-nutritional factors in the diet, e.g. residual trypsin inhibitors and lectins in soybean meal and some other vegetable proteins.

　　Using this combination with a standard dose of Buttiauxella-based phytase, producers can achieve consistent feed quality and body weight/calorie conversion improvements to save between $80,000 to $100,000 per million birds.

　　Observing how exogenous enzyme combinations (e.g. xylanase, amylase and protease) and other feed additives interact with the new generation of bio-efficacious phytases will be important to ensure that performance and cost benefits are delivered despite volatile market conditions.

　　References on request from info.animalnutrition@dupont.com.