食道瘘管法在放牧家畜采食习性研究中的运用

本文介绍了目前广泛运用于草地放牧研究中的食道瘘管法的发展、食道瘘管手术及护理、食道瘘管样的制取、食道瘘管样品用于放牧家畜采食的营养成分、植物成分、采食量和消化率方面的测定，以及与其它常用的方法——放牧前后样方测定法、扣笼与未扣笼双样方法和模拟家畜采食采摘法对放牧家畜采食的营养成分、植物成分、采食量和消化率测定的比较，认为代表放牧家畜真实采食日粮的食道疹管样在以上各项指标的测定中都优于其它测定方法所得到的样品，更能代表放牧家畜的实际采食习性。     

放牧家畜采食量估测方法研究进展

放牧家畜采食量是评价草地生态系统转化效率和动物生产力的主要参数,受草地植被生长情况、环境条件、放牧方式、家畜生理特征及其瘤胃内环境等因素影响。放牧家畜采食量的准确测定一直以来都是食性研究的难点和热点问题,关系到动物营养状态的评估、补饲策略的制定以及食性理论的探索。传统采食量估测方法大多基于观察法或放牧前后牧草生物量差值法,这些方法对动物的干扰较小,但是受技术本身和适用范围的限制,如未能估测单个动物的采食量,很难适用于大范围的采食量估测。链烷烃技术和近红外技术的出现为准确测定采食量提供了前所未有的机遇,不仅能克服传统测定方法的缺点,还在准确率、适用范围（圈养动物和放牧动物）等方面优势较为明显,但由于粪便回收率和数据库完整性等因素的影响,目前应用于生物多样性较高草地的放牧动物采食量估测尚有难度。在简要总结不同方法的原理和影响因素基础上,综述了差值法、内标法、链烷烃法和近红外法在放牧家畜采食量测定方面取得的最新进展及存在的问题,并建议多种方法结合可以准确测定放牧家畜采食量,以期为制定合理的草地生态系统管理策略和实现草地可持续生态服务功能提供新思路和启发。     

链烷技术估测典型草原放牧牛食性食量方法研究

为进一步探讨饱和链烷技术在典型草原自由放牧家畜中的应用,定量研究放牧牛食性及食量,于2004年夏秋季节在中国科学院内蒙古草原生态系统定位研究站典型草原进行自由放牧试验,选择体重相近4岁肉乳兼用哺乳牛4头,分两期测定其食性和食量,每头牛投喂一粒YC饱和链烷缓释胶囊,试验期内每天跟踪放牧牛的采食路线,收集其所采食的牧草及粪便样品,利用气相色谱分析牧草和粪样中的链烷含量,应用链烷技术估测放牧牛的排粪量、牧草采食比例和干物质采食量.结果表明:不同放牧季节放牧牛采食的牧草种类基本相同,但采食的比例存在差异,随放牧季节后移,放牧牛采食量显著增加(P<0.05),但日排粪量差异不显著.因此,链烷技术可以估测典型草原放牧牛的排粪量、食物组成和采食量,且放牧季节对放牧牛的采食量影响较大.建议在牧草种类组成较为复杂的典型草原估测放牧家畜食性食量时要进行多种方法比较,以进一步完善链烷技术.     

放牧生态系统家畜牧食行为研究进展

家畜牧食行为包括采食、反刍,游走,饮水,卧息和排泄粪尿,其中采食和反刍是两大主要行为。本文介绍了放牧家畜与牧草间的相互关系,放牧通过采食牧草,降低牧草光合叶面积指数而影响牧草生长发育。放牧作为一种人为干预,影响植被组成和群落结构,高放牧压力下,导致草地退化。在放牧情况下,牧草具有避牧和耐牧两种生存策略。由于放牧草地物种多样,家畜选择采食适口性高的植物或植物组成部分。介绍了国内外计算采食量的各种方法,包括计算放牧前后草地牧草生物量,通过内外源标记物计算排粪量或通过采食时间,单口采食率、单口采食量来计算采食量。家畜采食成分的测定一直以来都是难点,有直接观测法、瘤胃内容物或粪便镜检法、瘤胃瘘管法和炼烷烃技术等。     

链烷技术估测典型草原不同放牧率绵羊食性食量方法研究

为了进一步探讨饱和链烷技术在典型草原自由放牧家畜中的应用,定量研究自由放牧绵羊食性及食量,于2004年6-9月在中国科学院内蒙古草原生态系统定位研究站放牧样地进行试验,选择体重及体况相近、健康无病的二岁羯羊(内蒙古细毛羊×蒙古羊)60只,按体重(36.9±2.6) kg聚类分组,设置6种放牧率(0,1.33,2.67,4.00,5.33和6.67羊/hm²)的轮牧实验,绵羊采食量的测定选择放牧率为1.33,4.00和6.67羊/hm²的处理,试验开始,每只羊投喂1粒QSM饱和链烷缓释胶囊。食性测定选用全部的放牧率进行,同时辅助全粪法、扣笼法一同评价。试验期内定期收集试验地牧草样品及绵羊粪便样品,使用气相色谱分析牧草和粪样中的链烷含量,应用链烷技术估测放牧绵羊的排粪量、牧草采食比例和干物质采食量。结果表明,植物链烷模式存在种间差异,运用链烷技术估测的排粪量和实际测得排粪量差异不显著(P>0.05),放牧绵羊主要采食7~9种牧草,且不同放牧季节不同放牧率绵羊采食的牧草种类和比例不同,但采食量差异不显著(P>0.05)。本研究表明,运用链烷技术结合扣笼方法可以估测天然草地自由放牧家畜牧草的采食比例、干物质采食量和排粪量。     

放牧家畜采食量的测定

采食是动物-植物相互作用的重要途径,是维持生态系统物质和能量循环的主要过程。动物的生产水平和草地的可持续性取决于动物的采食量,明确放牧家畜采食量是草地管理的关键之一。目前,直接观测法、指示剂法、粪氮指数法和近红外光谱法等现有技术被广泛运用到采食量的测定中。直接观测法利用较低成本对采食量进行计算,但主观性较强;食道瘘管法能够把握采食量却忽略了动物福利;近红外光谱法和饱和链烷烃法在测定采食量的同时能够认识家畜的择食特征。为此,本文对现有常规测定方法进行综述,分析影响测定放牧家畜采食量的主要因素,并提出放牧行为与无人机技术相结合等新思路,为今后草原精准化管理提供技术支撑。     

反刍动物采食量的概念与研究方法

本研究对反刍家畜采食量的研究发展与现状进行了回顾与总结,采食量及其相关术语的定义主要基于饲草料或家畜,其测定方法和精确含义有差异;反刍家畜采食是由生物和非生物因素相互作用共同影响的复杂动态过程,采食量影响因子主要分为家畜的(胃肠蠕动力、选择性采食等)、饲草料的(粗纤维含量、抗营养成分等)和饲养条件的(草层结构、草地饮水点分布等)因素3个方面;采食量的测定方法有基于牧草测定的直接法和基于家畜测定的间接法,后者较多地应用于放牧家畜;预测方法有基于数学函数和生物学原理的模型法,基于消化试验的经验法和结合家畜属性的改进经验法。舍饲条件下可准确地测定和预测家畜的采食量,但对放牧家畜还没有精确的方法。通过测定与饲草水平密切相关的家畜尿液、血液或粪便中的代谢物水平将成为预测放牧家畜采食量的准确方法。     

放牧家畜采食量和择食性测定方法的研究进展

文章就国内外关于放牧家畜采食量和采食种类测定方法的研究现状进行了回顾与总结,分析了影响其测定的主要因素,并提出了合理的建议,为今后开展草地放牧家畜的采食量、择食性及其测定方法的研究提供了科学参考.     

放牧家畜采食量及其影响因素研究进展

放牧家畜采食量是家畜生产力的主要限制因子,同时也是决定放牧季节内的最适饲养管理标准。然而,近年来对放牧家畜采食量的研究主要集中于测定方法和放牧强度对家畜采食量的影响,没有系统的研究影响放牧家畜采食量的因素。本文通过分析不同放牧方式、不同放牧季节、不同放牧家畜和不同放牧草地状况对放牧家畜采食量的影响,以及不同放牧管理对家畜采食量的影响。从而为放牧家畜的科学管理和放牧草地的合理利用提供参考依据,同时提出了放牧家畜采食量研究今后需要进一步解决的问题。     

温带常见牧草中饱和烷烃浓度模式研究

利用气相色谱仪测定了7种温带常见牧草表皮蜡质层饱和烷烃(N-alkane)的浓度,对同一牧草种不同生育期的饱和烷烃模式进行方差分析.结果表明,不同生育期牧草饱和烷烃浓度模式存在显著的差异.在生长季节,绝大多数牧草的C29或C31的浓度超过50 μg/g,可以应用双烷烃法来估测放牧家畜的采食量.主成分分析和方差分析的结果表明,除了老芒麦与披碱草或羊草在9月份出现重叠外,其它牧草的饱和烷烃特征模式在各取样时间均出现显著差异.因此,在温带草原上,应用饱和烷烃技术估测放牧家畜的采食成分是可行的.     

放牧家畜养分消化率的测定

放牧家畜养分消化率反映牧草供给量和营养品质、家畜的健康状况以及生产性能等，是草原管理的关键指标之一。放牧家畜养分消化率的测定方法主要有直接测定和间接估测两种，直接法包括全收粪法、指示剂法、近红外光谱法（NIRS）等，间接法主要有体内或体外发酵法、牧草品质和气候等预测法。全收粪法是较精确的测定方法，然而耗时、费力，对家畜放牧行为有较大影响，难以体现牧场饲草供给的空间异质性；指示剂法根据不溶物的回收比例估测养分消化率，对家畜放牧行为干扰较小，指示剂不易收集，也不适于野性较高的放牧动物；NIRS法效率高、劳动强度低、成本小、不影响家畜，能够大尺度地估测放牧家畜的养分消化率，需要大量的实测数据完善预测模型；气候估测法快捷、省时，精确性较差，适于大时空尺度。放牧家畜的养分消化率与家畜、草地、放牧方法、温度、降水等生物因子，环境因子和社会因子密切相关，与遥感、无人机（UAV）和人工智能等结合，可以准确、快速地测定放牧家畜养分消化率，为草地生态修复与健康管理提供支撑。     

Grazing management as it affects nutrition, animal production and economics of beef production

Until recently, the nutritional fate of the grazing animal has been largely ignored by both animal and range scientists despite the economic dependence of the extensive livestock industry on nutrition from grass. Of the three factors that can be manipulated to improve profit gross margin per animal, is one that is directly affected by nutrition and, hence, grazing management. The relationship between economics and grazing management may be summarized as: Gross margin = f(Animal Performance); Animal Performance = f(nutrition); Nutrition = f(grazing). Economical beef production must consider the needs of the animal and the forage plant at the same time. The health of the sward must be maintained while improving individual animal performance and simultaneously increasing stocking rate. Generally, plants that have been defoliated require a period of recovery before again being grazed. A sward is kept in a vigorous state by preventing repetitive defoliation at the one extreme, and avoiding excessive shading (mature growth) of photosynthetic material at the other. This state is best achieved where livestock grazing is controlled. For any individual paddock, periods of grazing are followed by periods that allow adequate physiologic recovery of the plants. A grazing regimen that keeps the plant in a healthy state is fortuitously also well suited to the nutritional requirements of the animal. Animals on overgrazed pastures are likely to suffer from inadequate feed intake because of deficiencies in feed quantity. Conversely, on over-rested pastures, intake deficiency results from paucity in feed quality. On most unmanaged ranges, overgrazed and over-rested plants are likely to be found side by side. By controlling duration of the rest period as well as duration of the grazing period through pasture subdivision, requirements of both the plant and the animal can be met. With artificially high economic demands placed on animal production, some form of supplementation is required in most modern livestock situations. Whereas energy is frequently the nutrient limiting production it is seldom economically feasible to supplement the grazing animal directly with energy. Protein supplementation to increase forage intake, and thus indirectly energy intake, has become standard practice in many grazing situations. When there is adequate forage with a low crude protein content (less than or equal to 7%), microbially degradable protein is the preferred choice. However, when the animals are in an energy deficient state, either through a shortage of available forage or because their requirements exceed energy intake levels, by-pass protein is required.     

饱和链烷烃技术测定放牧动物营养状况的几个关键问题

针对利用饱和链烷烃技术测定放牧动物日粮组成和采食量,评价放牧动物营养状况时存在的几个易忽视的关键问题,即:日粮代表性样品获取、链烷烃缓释胶囊实际释放率、粪便中偶数外源指示剂(偶数碳原子烷烃)本底值、链烷烃粪便回收率测定的必要性和适宜方法,以及日粮组分链烷烃浓度模式主成分分析的必要性进行了综述,以期为链烷烃技术在放牧草食动物营养与生态研究中准确恰当的应用提供依据。     

Functional Classification of Feed Items in Pampa Grassland,Based on Their Near-Infrared Spectrum

Native pastures that present high botanical richness produce a variety of feed items for grazing herbivores. Diet selection takes place at the bite scale and, at a daily scale, the sum of bites composing the intake determines diet characteristics. The objective of this paper is to bring an original contribution to the understanding of diet selection in diverse foraging environments such as native Pampa grasslands. The issues are 1) to improve grazing management in Pampa ecosystems and 2) to evaluate the ability of native pastures to feed a herd in order to reduce supplementation and to improve the economic sustainability of extensive systems. We hypothesize that the information contained in the infrared spectra of plant samples corresponding to potential bites can be useful for establishing functional bite categories, which, in turn, can be used to understand and manage pastoral ecosystems. We analyzed the near-infrared spectrum (NIRS) of 1 515 bite samples gathered in 2012 using the continuous bite monitoring method applied to heifers continuously grazing on Pampa grassland at five grazing intensities (randomized block design with two replicates, applied since 1987). On the basis of the main wavelengths, a statistical classification of bite samples was produced and five classes were described: 1) small bites of wetland grasses and short grass; 2) medium bites of forbs and short grass; 3) small bites of short Poaceae and mixed species; 4) large bites on tussocks of Poaceae; and 5) extralarge bites on stiff tussock of Poaceae and Apiaceae. In order to evaluate the functional value of the classification, we tested its ability to take seasonal changes in pasture composition into account and to describe the variations in animal intake and performance in contrasted grazing conditions. We concluded that the NIRS is a good support for establishing functional classes of feed items that can be used to understand the foraging behavior and diet composition of grazing herbivores. Our approach was tested in Pampa grasslands grazed by cattle but should be applicable to a wide range of ecosystems, provided that chemical composition is more relevant for selection than feed item accessibility.     

Feeding value of pastures for ruminants

Perennial ryegrass is the primary forage component of ruminant diets in New Zealand. It is persistent and palatable, and immature ryegrass has a high nutritive value (NV). However, seed-head development substantially lowers its feeding value (FV) as fibre concentration increases, the rate and extent of digestibility decreases, and voluntary intake declines. Ryegrass pastures are susceptible to accumulation of endophytic and saprophytic fungi in dead material at the base of the sward, especially when mature and laxly grazed. Feeding forage legumes to ruminants grazing grass-dominant pastures will improve animal performance and lessen the reliance on a single species to meet all nutritional requirements.

The FV of forage is a function of intake and NV, measured by chemical analyses and animal feeding trials. Performance of individual animals grazing forages is usually limited by energy intake because structural fibre can slow digestion and clearance from the rumen and because of competition between individuals for available feed. The use of metabolisable energy (ME) content of forage to signify FV can give a reasonable indication of animal performance, but it should be used in conjunction with chemical analyses to improve the accuracy of predictions.

The relationship between FV, pasture production, animal performance and profitability is complex. The importance of skilled management to maintain pasture quality and optimise animal performance under inconsistent climatic conditions should not be underestimated. Acceptable animal performance with minimal veterinary intervention requires good nutrition, but the genetic potential of livestock in New Zealand cannot be met solely by grazing pasture, especially when a high utilisation of pasture is required to maintain quality and profitability.

Producers are responding to industry demands to reduce the seasonality in supply of milk and meat by changing lambing and calving dates, and extending lactation length in dairy cows. Social changes include adoption of once-daily milking in the dairy industry. Some changes have necessitated increased use of supplements and others can be met by feeding forages with a higher FV than ryegrass, all of which require an improved knowledge of feed quality. This information is available through rapid and inexpensive near infrared spectroscopy (NIRS) analysis, enabling animal nutritional needs to be balanced by appropriate nutrient supply. It is essential that producers continue to improve animal welfare, limit excessive use of fertilisers and meet the demands of overseas consumers. Good nutrition, with an increased use of legumes and other forages to complement ryegrass pastures, will enable these objectives to be achieved.     

Feeding value of pastures for ruminants

Perennial ryegrass is the primary forage component of ruminant diets in New Zealand. It is persistent and palatable, and immature ryegrass has a high nutritive value (NV). However, seedhead development substantially lowers its feeding value (FV) as fibre concentration increases, the rate and extent of digestibility decreases, and voluntary intake declines. Ryegrass pastures are susceptible to accumulation of endophytic and saprophytic fungi in dead material at the base of the sward, especially when mature and laxly grazed. Feeding forage legumes to ruminants grazing grass-dominant pastures will improve animal performance and lessen the reliance on a single species to meet all nutritional requirements. The FV of forage is a function of intake and NV, measured by chemical analyses and animal feeding trials. Performance of individual animals grazing forages is usually limited by energy intake because structural fibre can slow digestion and clearance from the rumen and because of competition between individuals for available feed. The use of metabolisable energy (ME) content of forage to signify FV can give a reasonable indication of animal performance, but it should be used in conjunction with chemical analyses to improve the accuracy of predictions. The relationship between FV, pasture production, animal performance and profitability is complex. The importance of skilled management to maintain pasture quality and optimise animal performance under inconsistent climatic conditions should not be underestimated. Acceptable animal performance with minimal veterinary intervention requires good nutrition, but the genetic potential of livestock in New Zealand cannot be met solely by grazing pasture, especially when a high utilisation of pasture is required to maintain quality and profitability. Producers are responding to industry demands to reduce the seasonality in supply of milk and meat by changing lambing and calving dates, and extending lactation length in dairy cows. Social changes include adoption of once-daily milking in the dairy industry. Some changes have necessitated increased use of supplements and others can be met by feeding forages with a higher FV than ryegrass, all of which require an improved knowledge of feed quality. This information is available through rapid and inexpensive near infrared spectroscopy (NIRS) analysis, enabling animal nutritional needs to be balanced by appropriate nutrient supply. It is essential that producers continue to improve animal welfare, limit excessive use of fertilisers and meet the demands of overseas consumers. Good nutrition, with an increased use of legumes and other forages to complement ryegrass pastures, will enable these objectives to be achieved.     

云贵高原石漠化地区人工草场营养价值评价研究

人工草地是云贵高原石漠化地区的主要放牧地。本研究通过放牧试验、饲喂试验和消化代谢试验相结合的方法,评价了云贵高原石漠化地区2个人工草场的营养价值和转化效率。放牧试验结果表明,相同放牧压力下,永善试验地的土壤养分、微量元素和牧草产量显著低于寻甸试验地,但两地人工草地中牧草的营养成分没有显著差异。饲喂试验结果表明,绵羊对永善试验地牧草的利用效率要高于寻甸试验地,绵羊对永善试验地牧草中Mg、Fe、Cu、Mn等元素的消化率和沉积率均显著高于寻甸试验地。消化代谢试验结果表明,寻甸试验地粗蛋白、粗脂肪、粗灰分、粗纤维、无氮浸出物等牧草养分的含量高于永善试验地,绵羊的消化率也高;采食量和体增重2个指标的各自变化趋势也和以上研究结果基本相同。上述结果表明,虽然永善试验地牧草土壤相对贫瘠,牧草产量低,但家畜转化效率高,因此高原石漠化地区应在牧草成熟期后放牧绵羊,并补饲一定的微量元素。     

Dietary Selection by Domestic Grazing Ruminants in Temperate Pastures: Current State of Knowledge,Methodologies, and Future Direction

Ruminants grazing mixed-species pastures face many choices, including when and where to graze and how much herbage to consume. These choices affect not only the nutritional status of the animal, but also sward composition and nutritive value through selective defoliation. Limited research has been conducted in the area of dietary selection and preference, most of which has been limited to simple model systems often involving a choice between only two herbage species. Although these studies have provided a vital tool to allow understanding of the fundamental principles of foraging behavior, in reality, grazing ruminants are faced with more complex situations. Understanding and managing animal preferences in mixed swards and thereby altering dietary selection can result in greater primary (plant) and secondary (animal) productivity. Key issues to improve this understanding include a better linking of behavioral and nutritional studies, a better understanding of the genetic factors influencing diet selection, and the development of more explicit spatial models of foraging behavior that incorporate multiple scales of decision making. This article, as part of a set of synthesis articles, reviews the current state of knowledge and research methodologies related to diet selection of grazing domestic ruminants with particular reference to improved temperate grazing environments, including how well we understand each part of the complex decision-making process a grazing ruminant faces, the links with primary and secondary productivity, and developments in methodologies. Finally, we identify key areas where knowledge is lacking and further research is urgently required.     

巍山县黄牛典型日粮组成及其营养水平的调查

通过调查巍山县肉牛饲料及饲养管理，测定饲料的常规养分，计算巍山县肉牛日粮中各养分含量，根据日粮中各养分供给量与需要量的差异来确定日粮组成是否合理，并对在实际生产中存在的问题提出相应的解决措施。