010第十章牧草利用.ppt

1、第十二章 牧草利用 Forage utilization,第一节 牧草品质 第二节 牧草利用 第三节 干草与青贮调制,第一节 牧草品质,Forage quality: the potential of a forage to produce the desired animal response,一、牧草品质与家畜生产力 二、饲草养分与自由采食 三、饲草成分 四、饲草分析,五、相对饲喂价值 六、饲草分析时的取样 七、影响饲草品质的因素,一、牧草品质与家畜生产力 forage quality and animal productivity,牧草品质包括牧草的营养价值、自由采食程度、抗营养因子成份

2、。 Forage quality encompasses nutritive value but is also a function of voluntary intake and the effects of any antiquality constituents.,Plant species and cultivar Climate Plant part Soil Plant maturity Pests,Climate Animal pests,Genotype Body size Sex,Age Body condition Animal health status Herd ef

3、fects,Nutritive value,Antiquality factors,Potential intake,Animal genetic factors,Physiological factors,Environmental factors,Forage quality,Plant/Animal interactions Balance of forage nutrients Extent of digestion Rate of digestion Utilization of digested nutrients Availability of forage Palatabili

4、ty of forage Antiquality of forage Interactions with feed supplements,Potential animal performance,Animal Performance ( milk production, weight gain etc.),Plant and animal factors affecting animal performance on forage,二、饲草成分与自由采食Forage composition and voluntary intake,以化学和解剖学分类，饲草包括两大部分：细胞内容物和细胞壁。

5、细胞内容物包括有机酸、蛋白质、脂肪、淀粉、糖类，易被反刍动物、非反刍草食动物甚至于单胃动物消化。 细胞壁，包括结构性碳水化合物（纤维素和半纤维素）、木质素、酚类化合物、角质、硅质。细胞壁成份的量、可消化性、消化速率是决定家畜生产力的关键因素。,一般消化程度高的饲草其采食量高。 干物质的可消化性与细胞壁含量呈负相关。 当纤维含量低时，家畜以较少的采食量即可满足其能量需要。 家畜的生理状态等影响对纤维性饲草的采食。,三、饲草成分Forage composition,1、细胞壁碳水化合物 Cell wall carbohydrates 2、木质素 Ligin 3、粗蛋白 Crude protein

6、4、矿物元素 Minerals,Forage composition -Cell wall carbohydrates,纤维素 Cellulose 葡萄糖以-1，4键相连的长链，以氢键相连为微纤维。 半纤维素 Hemicellulose 包括木糖、阿拉伯糖、甘露糖、半乳糖、葡萄糖、糖醛酸。 禾草细胞壁的半纤维素是豆科牧草的34倍。 果胶 Pectins 主要存在于初生壁和中层内，豆科牧草果胶含量一般高于禾草。幼嫩组织比成熟组织的果胶含量高。而且果胶的消化率高，消化快,Forage composition - Ligin,木质素的苯环结构增加了植物结构的刚性。 一般含3%12%。 正是由于不可消

7、化的木质素本身的物理效应与化学键合效应，使结构性碳水化合物的可消化性降低。,Forage composition - Crude protein,一般含蛋白氮60%80%。 硝酸态氮和游离氨基酸是主要的非蛋白氮。 豆科牧草CP含量15%20%，冷季型禾草的CP含量有可能与豆科牧草相似，热带禾草只有一半。 CP可划分为三部分：非蛋白氮、可消化蛋白氮、不可消化蛋白氮。,Forage composition - Minerals,含有动物生长发育所需的矿物元素。 P、Mg、Na、Se、Si、Cl、I、Cr、Co需要在日糖中添加。,四、饲草分析Forage analysis,对牧草品质，最终要通过饲喂

8、家畜后生产性能进行评价。 采食量常以代谢体重的百分比来计量。 body weight, BW, BW0.75 饲喂和放牧试验费用高。而实验室分析可以提供有效、相对廉价的相关信息。 常规饲草分析包括水分、CP、纤维、矿物质、DM可消化性、能量可利用性。,确定饲草的DM含量非常重要，使得评价的基础一致。 CP=N6.25 EE（ether extract）包括脂肪和其他可被醚浸出的物质。 Crude fiber是通过弱酸和弱碱浸提后的残渣，由于部分木质素可溶解于弱碱中，故此方法有误差。 灰分是灰化后的残渣。,1、范氏洗涤法 2、近红外光谱法 3、消化试验,1、范氏洗涤法 Forage analys

9、isThe Detergent Analysis System,1960，Peter J. Van Soest提出。 中性洗涤剂 neutral detergent solution 酸性洗涤剂 acid detergent solution 浓硫酸 72% sulfuric acid 灰化 高温,Detergent System Analysis,Plant constituent,Cell component,Cell contents,Cell wall,NDF,ND solubles,ADF,Protein Lipids Soluble Minerals Sugars Organic

10、acids Pectins Hemicellulose Cellulose Ligin Silica,NDF一般10%80%，同样消化率的豆科牧草NDF含量低于禾本科牧草。 ADF一般3%50%，同样消化率的豆科牧草与禾本科牧草的ADF含量一致。 在测定Ligin时，如果制备样品不当，也会造成误差，如Maillard reaction（sugar or amino acid combined when dried.）。,2、近红外光谱法 Forage analysisNear Infred Reflectance Spectroscopy,Early 1980s NIRS设备与软件开发后，减少

11、了劳力与费用。 通过对11002500nm近红外区H键与C、N、O的结合，可以精确测量饲草成份。 矿物质的测量较差。 不破坏样品。,3、消化试验 Forage analysisDigestibility,In vivo digestibility In vitro digestibility In vitro dry matter disapperance 两步法,五、相对饲喂价值relative feed value,RFV=(DDMDMI)/1.29 DDM=DM digestibility(%) DDM=88.9-(0.779ADF) DMI=voluntary DM intake(%

12、of BW) DMI=120/NDF,六、饲草分析时的取样Accurate sampling for forage analysis,Identify the lot of hay Choose an appropriate, sharp coring device Sample at random Take an adequate number of cores Use proper coring technique Handle hay sample properly Use the proper sample size Split samples,七、影响饲草品质的因素factors a

13、ffecting forage quality,1、植物解剖结构与形态结构 2、植物种 3、成熟期 4、叶茎比 5、收获与贮藏的影响,6、禾本科与豆科混播 7、施肥 8、环境与日动态变化 9、品种效应,1、植物解剖结构与形态结构plant anatomy and morphology,植物的不同组织其化学成份不同。 叶蛋白含量为茎的两倍，纤维含量低，消化率高。 不同组织养分品质差异是由于其形成细胞的不同而造成的。,叶肉细胞 mesophyll 初生壁 primary cell wall 木质部 xylem 次生壁 secondary cell wall 韧皮部 phloem 厚壁组织 scle

14、renchyma tissues,2、植物种plant species,一般豆科牧草比禾本科牧草的消化率高。 冷季型禾草比暖季型禾草的消化率高13%。 冷季型禾草和豆科牧草ADF含量与DM消化率相似，但是禾草的NDF含量高，采食量低。 C3植物一般比C4植物的品质好。,3、成熟期maturity stage,随着成熟，消化率和CP含量下降，NDF、ADF和其他纤维物质含量增加。 收获的饲草消化率随着生育期的延伸，每天下降0.3%0.5%。 对玉米青贮、小麦等牧草，消化率不会显著下降，其原因是籽粒。 芸苔属饲草的消化率不会有大的变化。,不同饲草，成熟度对饲草品质下降的影响不同。 成熟饲草影响采食

15、量。,4、叶茎比leaf : stem ratio,随着成熟，叶比重变小。 鸭茅营养早期叶占61%，开花末期只占23%。 繁殖生长的季节性变化影响叶茎比，从而影响饲草的品质。,5、收获与贮藏的影响harvest and storage effects,干草和青贮的饲草品质要比立株的差。 物理损失（叶片脱落）和呼吸损失（非结构性碳水化合物），雨淋损失（可溶性养分）。 豆科牧草雨淋损失比禾本科牧草大。 青贮比干草损失小。,6、禾本科与豆科混播grass-legume mixtures,比单纯禾本科草地NDF低，而CP含量高。,7、施肥fertilization effects on forage

16、quality,禾草施氮肥可提高产量和CP含量。 苜蓿高K含量降低Mg的可利用性，引起牧草抽搐症。,8、环境与日动态变化environmental effects and diurnal fluctuations,高温下生长饲草的品质差。木质素沉积增加。 低温下沉积糖和其他非结构性碳水化合物。 日间可溶性碳水化合物的含量变化。 下午比早上多。,9、品种效应cultivar effects,通过育种提高牧草品质。 春季，早熟品种比晚熟品种纤维含量低，消化率高。 多叶品种 木质素变异：brown midrib mutants,第二节 牧草利用,草食动物可以消化结构性碳水化合物，如纤维素、半纤维素，

17、以满足其能量需要。,网胃,/cud.html,瓣胃,皱胃,瘤胃,一、草食动物消化道解剖结构Digestive anatomy of herbivore 二、影响家畜生产性能的因素Factors affecting animal performance 三、氮素营养Nitrogen nutrition 四、饲草放牧利用Grazing utilization of forage,一、草食动物消化道解剖结构Digestive anatomy of herbivore,In a symbiotic共生 relationship, digestive tra

18、ct microorganisms of herbivores share energy extracted from cell walls with their host animals. Herbivores have also maintained the ability to use nonstructural carbohydrates, such as sugars and starch, as energy sources.,Low oxygen conditions ensure anaerobic respiratory metabolism (fermentation) o

19、f tract organisms. The volatile (short chain) fatty acids (VFAs) acetic (C2), propionic (C3), and butyric acid (C4) acids that are excreted by these organisms are absorbed through the rumen wall into the blood stream and form the primary energy source for the host herbivore.,Ruminants, including ovi

20、ne and bovine species, use an enlarged multicompartment modification of a simple stomach for fiber digestion by anaerobic fermentation; they are grouped as foregut fiber fermenters. Equids, which have a simple stomach and employ modifications of the hindgut, namely an enlargement of cecum 盲肠and colo

21、n结肠, for cell wall digestion by anaerobic fermentation, are classified as hindgut fiber fermenters.,In ruminants, digestion of fiber occurs primarily in the reticulorumen (simply referred to as the rumen ) comparment at the beginning of the digestive tract. In horses and other nonruminant aherbivore

22、s, fiber digestion occurs mainly in the cecum, located farther down the digestive tract beyond the small intestine.,By-products of rumen fermentation include considerable volumes of gases, mainly carbon dioxide (CO2) and methane (CH4) ,which must be expelled through eructation 嗳气to relieve pressure

23、on the rumen wall. Fiber-digesting livestock contribute to global warming because methane is a potent “greenhouse” gas. Recovery of useful energy released by cell wall digestion may be increased if methanogenesis is suppressed by fed additives such as monensin.,Copious quantities of saliva help to m

24、aintain rumen pH between 6 and 7 on most forage does, and low oxgen encourages rapid growth of rumen anaerobes. Acidity of the abomasum 皱胃 and other conditions farther down the tract are more like those of monogastrics.,Rumen volume and fiber digestion capability gradually increase until lambs are 2

25、 months old and calves reach 6 to 9 months old. Milk bypasses the immature foregut via a transient tublike inflexion (the reticular groove网胃沟) to the omasum 瓣胃.,二、影响家畜生产性能的因素Factors affecting animal performance,1、饲草可消化性forage digestibility 2 、能量分配energy partitioning 3、采食量intake 4、消化进程digestive proce

26、ss rates,1、饲草可消化性forage digestibility,Highly digestible of forages increase animal production largely by increasing their energy intake.,2 、能量分配energy partitioning,Gross energy,Digestible energy,Metabolizable energy,Feces energy,Heat loss,Growth, reproduction, lactation, synthesisi of woll,Urine ene

27、rgy,Methane energy,Net energy,Maintenance energy,3、采食量intake,Voluntary intake is not simply a forage characteristic but is also affected by animal species, sex, physiological status, and health status.,4、消化进程digestive process rates,The speed at which digestive processes proceed greatly affects anima

28、l performance. Important example are the rate of particle size reduction, the rate of digestion, and the rate of passage.,(1)消化速度rate of digestion,Digestion rate is the proportion or percentage of digestible material remaining in the rumen that gets digested during each hour. Digestion rate (K) rema

29、ins constant throughout the digestion process.,Cell contents digest at a consistently high rate but NDF (cell wall) digestion rates vary wildly across forage species and tissue types. Cell wall digestion rates vary from 0.02 to as much as 0.19/hour. Difference in cell wall digestion rate that seem s

30、mall can greatly affect total digestion time.,The time needed to complete digestion of one-half of the substrate (digestible cell wall in this case) can readily be calculated as 0.693/k.,(2)饲草降解速度rate of particle size reduction,Concurrent with digestions, particle size reduction is needed before und

31、igested residues can exit the rumen. Plant cell walls must be chewed, ruminated, and partially digested to reduce particle size to approximately 0.1 in. before they can pass through the reticulo-omasal orifice(网瓣口).,The rate at which particles are broken down by primary (biting and chewing) and seco

32、ndary (rumination) mastication or digestion to a size that can exit the rumen is a major factor influencing voluntary intake.,(3)饲草通过速度rate of passage,With forages that are high in cell walls or that have slow rates of digestion, residues spend more time in the rumen and the rate of passage is decre

33、ased. Mertens and Ely (1979) calculated that each 1% increase in rate of passage would translate into a 0.9% increase in maximum digestible dry matter intake.,三、氮素营养Nitrogen nutrition,Forage utilization by grazing livestock may be limited by N intake if the ingested herbage has less than 6% to 7% CP

34、. Most herbage protein (85% to 95%) is degraded in the rumen to ammonia by proteases secreted by rumen microorganisms. RDP,Ammonia is used to synthesize new microbial protein. Excess ammonia is converted to urea. Some urea is recycled in saliva but much of it is lost in the urine. Only small amounts

35、 of ingested dietary protein (so-called escape protein, by-pass protein, rumen undegraded protein, or protected protein) pass from the rumen and enter the abomasum via the omasum.,四、饲草放牧利用Grazing utilization of forage,1、采食策略grazing strategies 2、放牧家畜的能量代谢energy relations of grazing livestock 3、放牧与饱感的

36、相互作用interactions of grazing and gut fill 4、采食量与可食量intake and herbage allowance 5、抑制采食feeding deterrents 6、学习与选择diet learning and selection,1、采食策略grazing strategies,Evolutionary processes in ruminant progenitors separated grazing from rumination, minimized diet selection activities, and established e

37、ffective rumen detoxification解毒 processes. Ancestors of horses and other equids did not separate eating from particle size reduction.,2、放牧家畜的能量代谢energy relations of grazing livestock,Energy expended in grazing increases the net energy used for maintenance and decreases net energy available for growt

38、h and reproduction.,3、放牧与饱感的相互作用interactions of grazing and gut fill,Grazing patterns are controlled by the hunger/satiety in the mammalian brain. Hunger and satiety of grazing ruminants are primarily regulated by a gut fill mechanism.,4、采食量与可食量intake and herbage allowance,Herbage allowance describe

39、s the amount of herbage available to each livestock unit per unit of time and is , therefore, related to stocking rate and carrying capacity.,5、抑制采食feeding deterrents,The location of growing points of vegetative grasses at or below the soil surface Physical deterrents as hairs, sharp surface Chemica

40、l feeding deterrents,6、学习与选择diet learning and selection,Diet learning is particularly important for foals马驹 Herbivores use a number of cues in diet selection. Sight, taste, smell, feel,第三节 干草与青贮调制,一、饲草收获与贮藏Forage harvest and storage systems 二、干草调制 Hay 三、青贮 Silage,一、饲草收获与贮藏Forage harvest and storage

41、systems,Key considerations in selecting a harvesting system include:,The efficient preservation of crop nutrients Suitability for the forage species being grown and local climatic conditions Building, equipment, and costs associated with each system The nature of the livestock or cash forage enterpr

42、ise,Preservation as silage usually minimizes DM losses during harvest and storage. A large part of the DM lost in silage systems is lost during the storage phase, while the greatest losses for hay normally occur during harvest. Hay is suitable for transport and marketing,Estimated total harvest and

43、storage losses whenlegume-grass forages are harvested at varying moisturelevels and by different methods,二、干草调制 Hay,1、干草品质分级Hay grades 2、干草调制 Hay curing 3、干草生产 Hay production practices 4、干草贮藏 Hay storage,1、干草品质分级Hay grades,Based on forage analysis Include organoleptic (sensible) characteristics,2、干草

44、调制 Hay curing,To produce 1 ton of hay at 20% moisture, 4 to 5 tons of water need to be removed. In actual practice, 3 to 5 days or more of field curing are typically required to dry hay down to 20% moisture. Quick hay curing minimizing the respiration losses and maintain green color,(1) 气候因子Weather

45、factors (2) 饲草本身的因子 Crop factors (3) 管理因子 Management factors,(1) 气候因子Weather factors,Solar radiation intensity Air temperature Relative humidity Wind speed Soil moisture,(2) 饲草本身的因子 Crop factors,Plant species Crop maturity stage Crop yield level Initial moisture,(3) 管理因子 Management factors,Time of m

46、owing 刈割时间 Swath structure 草条结构 Windrow inversion 翻转草条 Tedding 摊晒 Mechanical or chemical conditioning 机械或化学调制 Raking 搂草,3、干草生产 Hay production practices,(1)Mowing 割草 (2)Conditioning调制 (3)Tedding and Raking 摊晒和搂草 (4)Baling打捆,(1)Mowing 割草,Cutting shoots 2 to 4 in. above the soil surface Reciprocating s

47、ickle mower Rotary disk mower,(2)Conditioning调制,Mechanical conditioning,Moving the mowed crop between tensioned intermeshing rubber rollers to open the cuticle表皮 layer Flail conditioners use rotating plastic or metal elements to abrade forage or bend and break stems.,http:/www.easy1780.easyisp.pl/ww

48、w/zbiory/kosiarki/stoll/Staalfingercrimper.jpg,Flail conditioners tend to lay the stems in different directions and the swath has a greater tendency to settle into the ground. Flail conditioners are not recommended for alfalfa but are commonly used for grass forages. Studies also indicate a 1%-3% dr

49、y loss compared to roller conditioners in alfalfa crops. They are also less expensive and as the swath is less uniform, difficult to obtain an even feed for silage choppers.,http:/mbforagecouncil.mb.ca/foragegrasslandmanual/7aharvestingfeedingstoredforagehay/74aphysiologyofhaydrying/default.aspx,Che

50、mical conditioning,Drying agent or desiccant material Potassium carbonate K2CO3,(3)Tedding and Raking 摊晒和搂草,Tedding disperses the crop so that it covers the entire field. Raking gathers the crop into windrows for balings.,(4)Baling打捆,Baling collects hay into packages for ease of handling, transport,

51、 and storage. Small rectangular bales Large rectangular bales Round bales,4、干草贮藏 Hay storage,Storage losses are about 5% for harvested near 15% moisture and stored under dry conditions.,(1)Rectangular bale storage方捆贮藏 (2)Round bale storage圆捆贮藏 (3)Hay preservation and barn drying干草贮存与室内干燥,(1)Rectangu

52、lar bale storage方捆贮藏,Pole barn with no walls Sheds enclosed on one to three sides Stacked enclosed Stacked outside covered to shed water,(2)Round bale storage圆捆贮藏,Storage losses range from 5% to as much as 40% Stored outside in contact with the ground and unprotected from the weather,(3)Hay preserva

53、tion and barn drying干草贮存与室内干燥,Effective hay preservative: Organic acids Buffered acids Ammonia sources,Artificial drying : Using heated or ambient air,三、青贮 Silage,Silage is forage preserved by anaerobic storage, usually under conditions that encourage fermentation of sugars to organic acids such as

54、lactic, acetic, and propionic acids.,Silages are classified according to their moisture levels,High-moisture silage: 70% moisture Wilted silage: 60% to 70% moisture Low-moisture silage (haylage) : 40% to 60% moisture,一、青贮微生物Silage microorganisms 二、青贮阶段Phase of silage preservation 三、青贮贮藏Silage storag

55、e,一、青贮微生物Silage microorganisms,1、乳酸菌 Lactic acid bacteria LAB,Homofermenters: lactic acid Heterofermenters: lactic acid, acetic acid, ethanol, CO2,2、肠细菌 Enterobacteria Coliform bacteria,虽然生成乳酸，但是： 同乳酸菌竞争糖类 以乙酸为主要终产品 提高缓冲能力buffering capacity( is the term used to describe the resistance to pH change i

56、n a solution or material) 生成CO2,3、梭菌 clostridia,可发酵糖、有机酸、蛋白质 产生丁酸，造成DM损失,From: Silage Science and Technology,4、真菌 Fungi,酵母菌 yeasts 霉菌 molds,二、青贮阶段Phase of silage preservation,1、有氧期aerobic 2、发酵期fermentation 3、稳定期stable 4、取饲期feedout,1、有氧期aerobic,Aerobic respiration Proteolysis Adequate packing, proper moisture, rapid filling, and good sealing, the aerobic phase lasts about 1 day. Producing CO2, water, heat,2、发酵期fermentation,Reduce the pH of ensiled forage to between 3.8 and 5.0 Lactic acid Acetic acid Propionic acid