【作者】 赵一广；

【导师】 刁其玉；

【作者基本信息】 中国农业科学院 ， 动物营养与饲料科学， 2012， 硕士

【摘要】 反刍动物排放的甲烷是一种能量的损失，也是导致全球变暖的重要温室气体之一。本论文以杜泊()×小尾寒羊()杂交肉用绵羊为试验动物，研究动物体重、日粮采食水平、能量水平、营养物质含量、营养物质摄入量、可消化营养物质、瘤胃可发酵营养物质、瘤胃液pH值和瘤胃液挥发性脂肪酸浓度对肉用绵羊瘤胃甲烷(CH4)排放的影响，旨在建立甲烷排放估测模型。具体分为以下两个部分：试验一日粮不同采食水平对肉用绵羊甲烷排放的影响选取15头日龄相近、体况良好、体重（36.60±0.93） kg的杂交绵羊母羊[杜泊()×小尾寒羊()]，采用单因素完全随机试验设计，将15头羊随机分为3个处理（每个处理5头羊），分别按自由采食（ad libitum， AL）、自由采食量的75%和自由采食量的55%三个饲喂水平投喂试验日粮，预试期10天，正试期10天。采用开路循环式呼吸测热系统，测定肉用绵羊24h CH4排放量。每只羊进入和离开呼吸测热代谢笼时均称重，平均值作为该羊呼吸测热体重。结果表明：限饲55%组、限饲75%组和自由采食组肉用绵羊的甲烷排放量分别为29.11、46.87和55.26L/d。自由采食组羊的甲烷排放量、甲烷能以及单位代谢体重的甲烷排放量均显著高于55%组（P<0.05）。甲烷排放量与日粮干物质采食量（DMI）、总能摄入量（GEI）和体重（BW）呈极显著线性正相关关系（P<0.01）。分别得到以下估测模型：甲烷与DMI的估测方程式：CH4(L/d)=44.034DMI (kg)-6.514(R~2=0.6801P=0.0005)；甲烷与GEI的估测方程式：CH4(L/d)=2.424GEI (MJ)-6.514(R~2=0.6801P=0.0005)；甲烷与BW的估测方程式为：CH4(L/d)=4.250BW(kg)-105.774(R~2=0.6713P=0.0006)。利用多元回归分析建立的甲烷与DMI、BW的多元回归估测方程式：CH4(L/d)=2.813BW(kg)+29.538DMI(kg)-88.760(R~2=0.9007P<0.0001)，与一元回归模型相比，显著提高了肉用绵羊甲烷排放量估测的相关性和准确性。试验二日粮不同营养组成对肉用绵羊甲烷排放的影响选取8头9月龄、体重（50.37±1.13） kg并安装有永久性瘤胃瘘管的杂交绵羊公羊[杜泊()×小尾寒羊()]，分别饲喂8种中性洗涤纤维（NDF）含量不同（分别为（%）51.83、50.47、44.58、42.34、38.20、35.43、30.10和27.03）的全混合日粮，进行8×4不完全拉丁方试验（8种日粮，4期试验）。每期试验21天，首先进行8天预试，而后于第9-16天采用开路循环式呼吸测热系统测定肉用绵羊甲烷排放，同时采用全收粪尿法进行消化代谢试验。在试验第17-19天，设置6个发酵时间点(0,6,12,24,48和72h)，采用瘤胃尼龙袋法测定日粮瘤胃可发酵营养物质含量。最后于试验第20天的8h、14h和20h以及第21天的2h、5h、11h、17h和23h分别采集瘤胃液，测定瘤胃液pH值和瘤胃液挥发性脂肪酸(VFA)浓度。结果表明，8种日粮每千克瘤胃可发酵有机物的甲烷排放量(L/kg FOM)分别为：81.64、87.22、77.42、61.87、52.19、54.90、57.07和58.72。甲烷能/消化能(CH4-E/DE)分别为：12.27%、11.04%、10.72%、9.52%、7.89%、8.17%、7.71%和8.92%。甲烷(L/kg FOM)与有机物摄入量(OMI)、总能摄入量(GEI)、粗蛋白摄入量(CPI)、可消化有机物(DOM)、消化能(DE)、可消化粗蛋白(DCP)、可消化粗脂肪(DEE)、丁酸/总VFA(TVFA)、戊酸/TVFA呈显著(P<0.05)负相关关系，而与NDF摄入量(NDFI)、酸性洗涤纤维摄入量(ADFI)、可消化NDF(DNDF)、可消化ADF(DADF)、瘤胃可发酵ADF(FADF)、瘤胃可发酵NDF(FNDF)/FOM、FADF/FOM和乙酸/TVFA呈显著(P<0.05)正相关关系。分别得到：甲烷与营养物质摄入量的回归模型：CH4(L/kg FOM)=0.182OMI (g)-0.547CPI (g)-1.177NDFI (g)+1.578ADFI(g)-3.396EEI (g)+154.950(R~2=0.9992P=0.0021)；甲烷与可消化营养物质的回归模型：CH4-E/DE(%)=92.902-3.259DE/GE(%)(R~2=0.8318P=0.0016)，CH4-E/DE (%)=0.180DADF/DOM(%)+5.251(R~2=0.9191P=0.0002)；甲烷与可发酵营养物质的回归模型： CH4-E/DE(%)=0.112FADF/FOM (%)+6.135(R~2=0.8887P=0.0005)；甲烷与瘤胃液VFA的回归模型：CH4(L/kg FOM)=0.825乙酸(mmol/L)+4.571丙酸(mmol/L)-7.159丁酸(mmol/L)-20.310戊酸(mmol/L)+10.493异戊酸(mmol/L)+9.030(R~2=0.9989P=0.0028)。综上所述，肉用绵羊瘤胃甲烷排放量随着动物体重、干物质采食量以及总能摄入量的增加而线性增加。日粮的精粗比或粗饲料含量直接影响肉用绵羊瘤胃甲烷排放量、甲烷能/总能和甲烷能/消化能之比。与其他营养物质相比，NDF和ADF与肉用绵羊甲烷排放相关性最强。与线性回归估测模型相比，多元回归模型提高了甲烷估测的相关性和准确性。因此，这些模型将有助于准确估测肉用绵羊的甲烷排放量。更多还原

【Abstract】 The emission of methane （CH4） from ruminants is a loss of energy and a significant contributor togreenhouse gas （GHG） emission resulting in global warming. The objectives of the present study wereto measure CH4emission from Chinese sheep and to develop prediction equations.Experiment1：Effects of different feeding levels on CH4emissions from sheepFifteen Dorper×thin-tailed Han crossbred, female lambs （36.60±0.93kg of BW） were randomlydivided into3groups with5sheep each and offered a pelleted mixture diet （concentrate:roughage=45:55） for ad libitum intake, or75or55%of the ad libitum （AL） intake, respectively. The experimentalduration consisted of a10-d adaptation period followed by a10-d period to measure CH4emissionsfrom sheep using an open-circuit respiration calorimetry system （Sable Systems International,Henderson, NV, USA）. Individual methane production was measured for24h. Body weight （BW） wasrecorded when each sheep entering and leaving the open-circuit respiration calorimetry system. TheCH4values for the groups of55%,75%and AL were29.11,46.87and55.26L/d, respectively。The CH4output, CH4energy and CH4per kg metabolisable BW （L/kg BW0.75） were increased significantly fromgroup55%to group AL（P<0.05）. CH4（L/d） was positively related to dry matter intake （DMI）, grossenergy intake （GEI） and BW linearly （P<0.01）. The relationship between CH4and DMI was CH4（L/d）=44.034DMI （kg）-6.514（R²=0.6801P=0.0005）; The relationship between CH4and GEI was CH4（L/d）=2.424GEI （MJ）-6.514（R²=0.6801P=0.0005）; The relationship between CH4and BW was CH4（L/d）=4.250BW（kg）-105.774（R²=0.6713P=0.0006）. The multiple relationship between CH4andDMI, BW was CH4（L/d）=2.813BW（kg）+29.538DMI（kg）-88.760（R²=0.9007P<0.0001）.Experiment2：Effects of different dietary composition on CH4emissions from sheepEight crossbred, non-castrated male lambs of Dorper×Thin-tailed Han sheep （50.4±1.1kg bodyweight （BW））, each fitted ruminal cannulae, were used in an incomplete8×4Latin square experiment（8diets and4periods of21d）. One of eight pelletized total mixed rations （TMR） with a neutraldetergent fiber （NDF） content of51.83,50.47,44.58,42.34,38.20,35.43,30.10and27.03, respectively,was offered randomly to each of the lambs and exchanged sequentially in four periods. Each periodconsisted of an8-d adaptation period and an8-d digestibility trial in metabolism cages during whichfeces and urine were collected, and CH4was measured by using open-circuit respirometrysimultaneous ly. The Nylon bag technique was used for the evaluation of ruminally fermentablenutrients with six different incubation times （0,6,12,24,48, and72h）. The ruminal pH andconcentrations of volatile fatty acids （VFA） were also measured. Prediction equations for CH4weredeveloped as linear and multiple regression models. The CH4values for the8diets were81.6,87.22,77.42,61.87,52.19,54.90,57.07and58.7L/kg fermentable organic matter （FOM）, respectively. TheCH4energy/digestible energy （CH4-E/DE） values were12.27,11.04,10.72,9.52,7.89,8.17,7.71and8.92%, respectively. CH4（L/kg FOM） was negatively related to organic matter intake （OMI）, gross energy intake （GEI）, crud protein intake （CPI）, digestible organic matter （DOM）, digestible energy （DE）,digestible crude protein （DCP）, digestible ether extract （DEE）, butyrate/total VFA （TVFA） andvalerate/TVFA （P<0.05）, but positively related to NDF intake （NDFI）, acid detergent fiber intake（ADFI）, digestible NDF （DNDF）, digestible ADF （DADF）, fermentable ADF （FADF）, fermentableNDF （FNDF）/FOM, FADF/FOM, and acetate/TVFA （P<0.05）. The relationship between CH4andnutrients intake was CH4（L/kg FOM）=0.182OMI（g）-0.547CPI（g）-1.177NDFI （g）+1.578ADFI（g）-3.396EEI（g）+154.950（R²=0.9992, P=0.0021）. The relationships between CH4and digestiblenutrients were CH4-E/DE（%）=92.902-3.259DE/GE（%）（R²=0.8318P=0.0016） and CH4-E/DE （%）=0.180DADF/DOM （%）+5.251（R²=0.9191P=0.0002）. The relationship between CH4and ruminalfermentable nutrients was CH4-E/DE （%）=0.112FADF/FOM （%）+6.135（R²=0.8887P=0.0005）. Therelationship between CH4and ruminal VFA was CH4（L/kg FOM）=0.825Acetate （mmol/L）+4.571Propionate （mmol/L）-7.159Butyrate （mmol/L）-20.310Valerate （mmol/L）+10.493Isovalerate （mmol/L）+9.030（R²=0.9989P=0.0028）.In conclusion, CH4increased linearly as the BW, DMI and GEI increased. CH4, CH4-E/GE andCH4-E/DE were affected by the ratios of forage to concentrate or dietary roughage content. Comparedwith other nutrients, NDF and ADF were more reliable to estimate CH4production with higherprecision. Compared with the linear regression models, the multiple regression models clearly provideda higher accuracy and correlation. Therefore, they may be useful to improve the prediction of CH₄emissions from Chinese sheep.更多还原