維生素是健康和生產的重要營養

007畜牧 · 發表于 2013-6-19 11:50:16

本帖最后由 007畜牧于 2013-7-19 16:10 編輯

　　維生素是健康和生產的重要營養

　　Gilberto Litta, 帝斯曼全球維生素類產品管理者,
文章發表日期： 2013年6月17日

　　沒有維生素，豬就不會生長得如養豬人所愿。將要發表的是三篇文章將翻新維生素的大眾知識-維生素存在于什么之中，哪些是豬不可或缺的，如何使用維生素做配方。

　　微生物營養很好理解，也是多年來也得到廣泛研究的主題。這個領域已經取得了有價值的工具，它可確保家畜在飼養過程中在動物的健康，生長和飼料效率方面提供給人類認識它們遺傳潛力的最好機會。維生素不僅僅能顯著推動生產經濟和動物福利，也能在減少農場和食品生產的碳足跡方面起到重要作用。
　　維生素常通過日糧預混料添加入整個飼料計劃中，典型的添加量是每噸配合飼料成品添加25kg。單一的維生素添加量可能為每噸成品添加5-50g，普通飼料的混合均勻度精確度是由維生素和預混料生產商、配合飼料生產商和家庭混合農場管理的。
　　維生素 - 它們曾經被認為是“重要的胺類”-對于從低端明顯的缺乏癥狀一直到中端和動物性能的相關曲線維生素都發揮了廣泛的作用。至于高端高添加水平則集中于特殊效應，如增強免疫效應或肉質特征（圖1）。
　　在制定完整的飼料計劃時，中間部分是企業操作的，圖1給出了依據斷奶后仔豬生長期望值制定的維生素添加水平。應該避免添加量的極限值，因為它也是一種取得最大效益的經濟必要性。

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　　維生素 - 定義&功能
　　首先介紹維生素功能的一些基本概念。維生素是動物生命和福祉的關鍵活性成分，這適用于仔豬，生長/育肥豬，母豬也包括公豬。維生素有兩個基本屬性：
　　1. 日糧需求的每種維生素量很小 - 通常以 mg 或 μg計量。
　　2.維生素是有機化合物，因此它不同與微量礦物質營養。
　　維生素有催化劑作用：它們能促進其他營養物質的合成和降解，因此在控制一般代謝過程中起重要的作用。它們總是為最佳健康和正常生理功能如生長，身體發育和繁殖所需。大多數維生素不能由動物本身合成，它們必須從飼料中獲取。
　　表1給出動物營養以及每一個基本功能所需的主要維生素。可以看出，許多維生素成分影響了一般生長，飼料效率和健康狀態。換句話說它們對整個動物性能和效益有著深遠的影響。

　　豬的缺乏癥狀
　　維生素缺乏癥狀在農場中仍可定期見到。癥狀可能是生物素缺乏引起的嚴重壞死，母豬維生素C引發的肚臍出血以及泛酸缺乏引起的母豬后腿叉開。

　　維生素缺乏癥的原因是多種多樣的，但是相當重要的是不充足的飼料采食量（管理原因），這很難避免維生素攝入不充足。維生素拮抗劑的存在也是一個原因。錯誤地添加和不良的配方是最主要的問題。由慢性或急性疾病導致不良的消化以及之后的吸收也是一個主要因素。
　　維生素需求
　　單一的維生素需求有很大的不同，受維生素之間積極和消極相互作用影響。因此維生素永遠不能獨立看待，作為整體考慮效果更好。如脂溶性維生素必須以正確的添加比例添加，因為它們都在爭奪腸道吸收。水溶性維生素也是蛋白質、脂肪和碳水化合物（能量）中間代謝的調節物，缺乏其中的一種都會增加其他品種需求。

　　圖2提出了一個維生素之間復雜的相互作用，這可造成飼料中維生素單個品種很難達到需求水平。從表1中可以看出幾乎所有的羅列維生素都與檸檬酸循環中的能量代謝有相互作用功能，它們也與控制氨基酸庫，達到蛋白質沉積和瘦肉組織生長這個過程有交叉作用。
　　效應
　　維生素應用都是在成品飼料中添加相當小的數量，但是終產品中這個成分的效應對生產，飼料效率和繁殖都有重大影響。
　　一些維生素對胴體品質也有顯著的作用。商業營養中維生素的真正添加量也是一個遺傳改良中的“流動的盛宴”，它不斷改變游戲規則，未來的研究能提出一些新的見解。帝斯曼公司估計由于生長豬的基因不斷變化，每年都有1%的維生素需求變化。
　　隨著不斷變化的選擇和飼料轉化的改善，飼料采食量本身隨著時間趨向下降。因此，有必要修改實際生產中的維生素，以便維持每天每頭動物的消耗量。另外，現代養殖業生產方法論對最佳放養密度和大型密集規模都有影響作用。這個作用能誘發家畜的慢性應激反應，隨后影響維生素需求和飼料攝入濃度。
　　養殖者和農場管理者帶回的消息是他們應該知道這些問題和關系，了解他們的動物和農場效應。帝斯曼營養生產中心開設了最佳維生素營養概念，本中心旨在為家庭經營者提供商業營養師和營養顧問，并為高精準配方提供有效的指導工具和指導。在接下來的兩篇文章中將討論維生素各品種對豬的價值以及在日糧配方中的使用。
譯者：IRIS
英文來源：pigprogress.net
翻譯時間：2013年6月19日

Vitamins – vitalnutrients for health and production

Without vitamins pigs cannot grow as theindustry wants them to do. In this series of three articles, general knowledgeon vitamins is refreshed – what vitamins exist, which ones are indispensiblefor pigs and how to formulate diets with vitamins?

Vitamin nutrition is understood very well and has been the subject ofcomprehensive research over many years. This has yielded valuable tools toensure that domestic animals in human care are given the best opportunity torealise their genetic potential in terms of health, growth and feed efficiency.Not only do vitamins contribute significantly to production economy and animalwelfare but they also play a major role in reducing the carbon footprint fromanimal farming and food production.

Vitamins are normally added to the overall feed programme via the premixcomponent of the diet and typically this might be 25kg inclusion into a tonneof finished compound feed. Where the calculated inclusion of a specific vitaminmight be 5-50g per tonne of finished feed, the precision of the mix dispersionand general feed manufacture must be carefully managed by the vitamin andpremix manufacturer, the compound feed manufacturer and the home mixing farmer.

Vitamins – or as they were known at one time ‘vital amines’ – have a range ofactivities in animal feed programmes from the low end where deficiency symptomsare evident (and these are well documented) all the way through to the middlerange where there are curvilinear relationships with animal performance. Thenthere is the top end to very high levels of input, where effect is focused onspecial applications like boosting immune response or meat quality traits.

In formulating complete feed programmes, this middle band is where the industryoperates. Figure 1 (see attached pdf) gives a schematic illustration of thelevels of general vitamin inputs towards the expectation of post-weaning pigletgrowth. Extremities of input should be avoided but it is also an economicnecessity to strike the correct optimum position for maximum profitability.

Vitamins – definitions& functions
Firstly some basic notions on vitamin functions. Vitamins are active substancesessential for the life and well-being of the animal and this applies topiglets, growing/finishing pigs, sows and also boars. Vitamins arecharacterised by two basic properties:
1. Daily requirements for each vitamin are very small – usually measured in mgor μg.
2. Vitamins are organic compounds and hence differ in this respect from tracemineral nutrients.

Vitamins express catalytic functions: they can facilitate both synthesisand degradation of other nutrients – and therefore play a major role in thecontrol of general metabolism. They are always required for optimum health andnormal physiological functions such as growth, body development andreproduction. Most vitamins cannot be synthesised by the animals and they mustbe obtained from the feed.

In Table 1 (seeattached pdf) a general description ofthe major vitamins that are required in animal nutrition is given plus a basicfunction for each. It can be seen that many of these compounds impact ongeneral growth, feed efficiency and health status - in other words they have aprofound influence on the overall performance and profitability of the animal.

Deficiency symptoms inpigs
Vitamin deficiency symptoms are still seen on pig farms on a regular basis.Symptoms could be severe necrosis due to biotin deficiency, navel bleeding dueto a vitamin C deficient sow and splayed hind legs due to pantothenic aciddeficiency.

The reasons why vitamin deficiencies arise are many and varied but not leastdue to an inadequate feed intake (for management reasons) which is inextricablylinked to inadequate vitamin intake. The presence of vitamin antagonists isalso a cause. Mixing errors and poor formulation are a major problem. Poordigestion and hence absorption due to chronic or acute diseases are also majorcauses.

Vitamin requirements
Specific vitamin requirements vary widely and are influenced by the fact thatmany vitamins have positive or negative interactions amongst them. Vitamins cantherefore never be considered in isolation but better as a whole programme. Fatsoluble vitamins, for example, must be fed in correct ratios as they allcompete for intestinal absorption. Water soluble vitamins are also regulatorsof the intermediary metabolism of protein, fats and carbohydrates (energy) anda lack of any one can increase the need for the others.

Figure 2 (see attached pdf) presents a schematic to show the complexity of vitamin interactions andthe consequence of this is the difficulty in arriving at specific requirementsfor individual vitamins in the feed. It can be seen from this representationthat almost all of the vitamins listed in Table 1 have an interactive functionin both energy metabolism via Krebs Cycle and also in protein deposition andlean tissue growth via the control of the amino acid pool.

Impact
Vitamin applications are used at relatively small inclusions into finishedfeeds but the impact of this component on the finished feed has majorconsequences for growth, feed efficiency and reproductive processes. Somevitamins also have significant effects on carcass the quality. The actualvalues applied in commercial nutrition are also very much a ‘movable feast’ in thatgenetic improvement constantly changes the game and further research gives newinsights. DSM estimate that due to constant genetic change in growing pigsthere is likely to be a 1% change every year in overall vitamin requirements.

With constant selection and improvement of feed conversion ratios, feed intakeitself tends to be reduced over time. Thus, there is a need to revise theactual in-feed concentrations of vitamins to maintain the daily consumption peranimal. In addition, there is also an effect of modern animal productionmethodology at optimum stocking densities and in large populations underintensive conditions. This can induce chronic stress reactions in livestock,subsequently affecting vitamin requirements and in-feed concentrations.

The take home message for producers and farm managers is that they should beaware of these issues and relationships and understand the effects on their ownanimals and farm units. DSM Nutritional Products have developed the OptimumVitamin Nutrition concept, aimed at providing commercial nutritionists andnutritional advisers to home mixers with effective tools and guidelines forhigh precision formulation. The next two articles in this series will discussspecific vitamin values for pigs as well as the formulation of working diets.