肉羊甲烷排放测定与模型估测

【目的】研究日粮不同营养物质含量和消化性能对肉羊瘤胃甲烷排放的影响，并建立甲烷排放估测模型。【方法】选取8头月龄相近、体重（50.37±1.13） kg的成年杂交绵羊公羊（杜泊（♂）×小尾寒羊（♀）），分别饲喂8种中性洗涤纤维（neutral detergent fiber，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。试验分为4期，每期16 d，于第9—16天采用Sable呼吸测热系统测定甲烷，用全收粪法进行消化试验。【结果】8种日粮每千克可消化有机物的甲烷排放量（L?kg-1 DOM）分别为48.80、46.98、45.38、41.34、35.44、34.66、33.73和37.83。甲烷与NDF回归模型：CH4E/DE（%）=0.14688DNDF/DOM（%）+5.47643（R2=0.9084，P=0.0003）。甲烷与酸性洗涤纤维（ADF）回归模型：CH4 （L?kg-1 DOM）=0.14411DADF（g）+23.69940（R2=0.8367，P=0.0015）。甲烷与营养物质摄入量：CH4（L?kg-1 DOM）=-0.22260OMI（g）+0.15234CPI（g）+0.06465NDFI（g）-0.60549EEI（g）+218.23715（R2=0.9786，P=0.0077）。甲烷与可消化营养物质：CH4（L?kg-1 DOM）=0.09722DCP（g）+0.12079DNDF（g）-0.08355DADF（g）-1.71035DEE（g）+47.85414（R2=0.9776，P=0.0083）。【结论】日粮的精粗比或粗饲料含量直接影响单位可消化有机物的甲烷排放量及甲烷能/总能、甲烷能/消化能之比。在直线回归中，与其它营养物质相比，NDF和ADF与肉羊甲烷排放相关性最强。与直线回归相比，多元回归提高了甲烷估测的相关性和准确性。

Estimation and Regression Models of Methane Emissions from Sheep

【Objective】 This trial was designed to study the effects of dietary nutrients and their digestibility on rumen methane (CH4) emissions from sheep and develop regression models. 【Method】 Eight adult crossbreed rams (Dorper (♂) ×Small Tail Han sheep (♀)) with the body weight of (50.37±1.13) kg were fed 8 total mixed rations with different NDF content of 51.83%, 50.47%, 44.58%, 42.34%, 38.20%, 35.43%, 30.10% and 27.03%, respectively. The experiment design was 8×4 incomplete Latin square which lasted for 4 periods and each period lasted for 16 d. CH4 was measured by sable open-circuit respiration calorimetry system with 3 sheep once and digestive trials were conducted by total feces collection method during the last 8 d of each period. 【Result】 CH4 per kg digestive organic matter (L?kg-1 DOM) of 8 diets was 48.80, 46.98, 45.38, 41.34, 35.44, 34.66, 33.73 and 37.83, respectively. Methane regressed to NDF, ADF, nutrient intake and digestive nutrients were CH4E/DE (%)=0.14688DNDF/DOM (%)+5.47643 (R2=0.9084, P=0.0003), CH4 (L?kg-1 DOM)=0.14411DADF(g)+23.69940 (R2=0.8367, P=0.0015), CH4 (L?kg-1 DOM)=-0.22260OMI (g)+0.15234CPI (g)+0.06465NDFI (g)-0.60549EEI (g)+218.23715 (R2=0.9786, P=0.0077) and CH4 (L?kg-1 DOM)=0.09722DCP (g)+0.12079DNDF (g)-0.08355DADF (g)-1.71035DEE (g)+47.85414 (R2=0.9776, P=0.0083), respectively.【Conclusion】CH4 (L?kg-1 DOM), CH4E/GE and CH4E/DE were affected by the ratio of forage to concentrate (F﹕C) or dietary roughage content. In the linear regression models, NDF and ADF were more reliable than other nutrients to estimate methane emissions with higher precision. Compared with the linear regression models, the multiple regression models clearly provided a higher accuracy and a stronger correlation.