维生素是健康和生产的重要营养

007畜牧 · 发表于 2013-6-19 11:50:16

本帖最后由 007畜牧于 2013-7-19 16:10 编辑

　　维生素是健康和生产的重要营养

　　Gilberto Litta, 帝斯曼全球维生素类产品管理者,
文章发表日期： 2013年6月17日

　　没有维生素，猪就不会生长得如养猪人所愿。将要发表的是三篇文章将翻新维生素的大众知识-维生素存在于什么之中，哪些是猪不可或缺的，如何使用维生素做配方。

　　微生物营养很好理解，也是多年来也得到广泛研究的主题。这个领域已经取得了有价值的工具，它可确保家畜在饲养过程中在动物的健康，生长和饲料效率方面提供给人类认识它们遗传潜力的最好机会。维生素不仅仅能显著推动生产经济和动物福利，也能在减少农场和食品生产的碳足迹方面起到重要作用。
　　维生素常通过日粮预混料添加入整个饲料计划中，典型的添加量是每吨配合饲料成品添加25kg。单一的维生素添加量可能为每吨成品添加5-50g，普通饲料的混合均匀度精确度是由维生素和预混料生产商、配合饲料生产商和家庭混合农场管理的。
　　维生素 - 它们曾经被认为是“重要的胺类”-对于从低端明显的缺乏症状一直到中端和动物性能的相关曲线维生素都发挥了广泛的作用。至于高端高添加水平则集中于特殊效应，如增强免疫效应或肉质特征（图1）。
　　在制定完整的饲料计划时，中间部分是企业操作的，图1给出了依据断奶后仔猪生长期望值制定的维生素添加水平。应该避免添加量的极限值，因为它也是一种取得最大效益的经济必要性。
图1.jpg

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　　维生素 - 定义&功能
　　首先介绍维生素功能的一些基本概念。维生素是动物生命和福祉的关键活性成分，这适用于仔猪，生长/育肥猪，母猪也包括公猪。维生素有两个基本属性：
　　1. 日粮需求的每种维生素量很小 - 通常以 mg 或 μg计量。
　　2.维生素是有机化合物，因此它不同与微量矿物质营养。
　　维生素有催化剂作用：它们能促进其他营养物质的合成和降解，因此在控制一般代谢过程中起重要的作用。它们总是为最佳健康和正常生理功能如生长，身体发育和繁殖所需。大多数维生素不能由动物本身合成，它们必须从饲料中获取。
　　表1给出动物营养以及每一个基本功能所需的主要维生素。可以看出，许多维生素成分影响了一般生长，饲料效率和健康状态。换句话说它们对整个动物性能和效益有着深远的影响。
表1.jpg

　　猪的缺乏症状
　　维生素缺乏症状在农场中仍可定期见到。症状可能是生物素缺乏引起的严重坏死，母猪维生素C引发的肚脐出血以及泛酸缺乏引起的母猪后腿叉开。

　　维生素缺乏症的原因是多种多样的，但是相当重要的是不充足的饲料采食量（管理原因），这很难避免维生素摄入不充足。维生素拮抗剂的存在也是一个原因。错误地添加和不良的配方是最主要的问题。由慢性或急性疾病导致不良的消化以及之后的吸收也是一个主要因素。
　　维生素需求
　　单一的维生素需求有很大的不同，受维生素之间积极和消极相互作用影响。因此维生素永远不能独立看待，作为整体考虑效果更好。如脂溶性维生素必须以正确的添加比例添加，因为它们都在争夺肠道吸收。水溶性维生素也是蛋白质、脂肪和碳水化合物（能量）中间代谢的调节物，缺乏其中的一种都会增加其他品种需求。
图2.jpg

　　图2提出了一个维生素之间复杂的相互作用，这可造成饲料中维生素单个品种很难达到需求水平。从表1中可以看出几乎所有的罗列维生素都与柠檬酸循环中的能量代谢有相互作用功能，它们也与控制氨基酸库，达到蛋白质沉积和瘦肉组织生长这个过程有交叉作用。
　　效应
　　维生素应用都是在成品饲料中添加相当小的数量，但是终产品中这个成分的效应对生产，饲料效率和繁殖都有重大影响。
　　一些维生素对胴体品质也有显著的作用。商业营养中维生素的真正添加量也是一个遗传改良中的“流动的盛宴”，它不断改变游戏规则，未来的研究能提出一些新的见解。帝斯曼公司估计由于生长猪的基因不断变化，每年都有1%的维生素需求变化。
　　随着不断变化的选择和饲料转化的改善，饲料采食量本身随着时间趋向下降。因此，有必要修改实际生产中的维生素，以便维持每天每头动物的消耗量。另外，现代养殖业生产方法论对最佳放养密度和大型密集规模都有影响作用。这个作用能诱发家畜的慢性应激反应，随后影响维生素需求和饲料摄入浓度。
　　养殖者和农场管理者带回的消息是他们应该知道这些问题和关系，了解他们的动物和农场效应。帝斯曼营养生产中心开设了最佳维生素营养概念，本中心旨在为家庭经营者提供商业营养师和营养顾问，并为高精准配方提供有效的指导工具和指导。在接下来的两篇文章中将讨论维生素各品种对猪的价值以及在日粮配方中的使用。
译者：IRIS
英文来源：pigprogress.net
翻译时间：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.