肉用绵羊生长期甲烷排放特点与预测模型的建立
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摘要
【目的】通过探索生长期肉用绵羊的甲烷(CH_4)排放规律,旨在建立相关的CH_4预测模型。【方法】采用单因素试验设计,以饲粮NFC/NDF(非纤维性碳水化合物/中性洗涤纤维)为0.78自由采食组的平均日增重作为饲粮NFC/NDF为1.03组和2.17组的限饲标准,在此基础下测定肉用绵羊的生长性能、营养物质消化率和甲烷产量,并分析肉用绵羊不同体重阶段的甲烷产量与饲粮干物质基础下的营养物质含量、营养物质摄入量、可消化营养物质摄入量及营养物质消化率间的回归关系。【结果】预测肉用绵羊生长早期(25—35 kg)CH_4产量的最佳一元和多元回归模型分别为:CH_4(L·d~(-1))=-26.58×NFC/NDF+92.7(R~2=0.772,P <0.001);CH_4 (L·d~(-1))=2.71×NDFD-2.45×DMD-0.97 CPD+124.46(R~2=0.846,P=0.001)。预测肉用绵羊生长后期(48-55 kg)CH_4产量的最佳一元和多元回归模型分别为:CH_4 (L/d)=-57.00×GE (MJ·kg~(-1))+1076.0(R~2=0.581,P=0.002);CH_4/BW~(0.75) (L/kg0.75)=-0.013×NDF intake (g/d)-0.13×CP intake (g/d)+0.02×DM intake (g/d)+0.84(R~2=0.652,P=0.019)。而肉用绵羊生长期整体CH_4产量的最佳一元和多元预测模型分别为:CH_4(L/d)=-26.94×NFC/NDF+90.71(R~2=0.655,P <0.001);CH_4/BW~(0.75) (L/kg0.75)=0.005×Digestible NDF intake (g·d~(-1))+0.011×Digestible DM intake (g·d~(-1))-0.097×Digestible CP intake (g·d~(-1))-4.78 (R~2=0.722,P <0.001)。【结论】建立了肉用绵羊独立生长阶段(25—35 kg、48—55 kg)和整体生长阶段(25—55 kg)的CH_4预测模型。研究表明,处于不同体重阶段的肉用绵羊的最佳甲烷预测因子不尽相同,且甲烷产量受饲粮NFC/NDF影响较大。这可为今后评估我国饲养模式下的甲烷产量提供理论依据,也可为肉用绵羊饲粮的合理配制提供技术参考。
【Objective】 This study was aimed to investigate the methane(CH_4) emission and develop CH_4 prediction models of growing sheep. 【Method】 The average daily weight gain of the treatment of NFC/NDF = 0.78, 1.03 and 2.17 was used as the reference for the restricting level of feed for the other three treatments, respectively, and the digestibility of nutrients and methane production of meat sheep were measured on this basis. Furthermore, the regression relationships were established between CH_4 production and dietary nutrient content, nutrient intake, digestible nutrients intake, and apparent digestibility of nutrients. 【Result】When the sheep grew from 25 to 35 kg BW, the most accurate single-variable and multivariate regression model were shown below:CH_4(L/d)=-26.58 × NFC/NDF + 92.70(R~2 = 0.772, P <0.001); CH_4(L/d) = 2.71 × NDFD-2.45 × DMD-0.97 × CPD + 124.46(R~2 = 0.846, P = 0.001). When the sheep grew from 48 to 55 kg BW, the most accurate single-variable and multivariate regression model were shown below: CH_4(L/d) =-57.00 × GE(MJ·kg~(-1)) + 1076.01(R~2 = 0.581, P = 0.002); CH_4/BW~(0.75)(L·kg~(-1)) =-0.01 ×NDFI(g·d~(-1))-0.13 × CPI(g·d~(-1)) + 0.02 × DMI(g·d~(-1)) + 0.84(R~2 = 0.652, P = 0.019). The most accurate single-variable and multivariate regression model in the overall growing period of sheep were shown below: CH_4(L/d)=-26.94 × NFC/NDF + 90.71(R~2 = 0.655, P <0.001); CH_4/BW~(0.75)(L·kg~(-1)) = 0.005 × DNDFI(g·d~(-1)) + 0.011 × DDMI(g·d~(-1))-0.097 × DCPI(g·d~(-1))-4.78(R~2 =0.722, P <0.001). 【Conclusion】 The regression relationships were established for the respective growth periods(25-35 kg and48-55 kg BW) and the overall growth period(25-55 kg BW). The studies showed that the optimal methane prediction factors for meat sheep at different weight were various, and methane production was greatly affected by dietary NFC/NDF, which could be used as a theoretical basis for the evaluation of methane production under the breeding model in China and a reference for the diets of meat sheep.
【Objective】 This study was aimed to investigate the methane(CH_4) emission and develop CH_4 prediction models of growing sheep. 【Method】 The average daily weight gain of the treatment of NFC/NDF = 0.78, 1.03 and 2.17 was used as the reference for the restricting level of feed for the other three treatments, respectively, and the digestibility of nutrients and methane production of meat sheep were measured on this basis. Furthermore, the regression relationships were established between CH_4 production and dietary nutrient content, nutrient intake, digestible nutrients intake, and apparent digestibility of nutrients. 【Result】When the sheep grew from 25 to 35 kg BW, the most accurate single-variable and multivariate regression model were shown below:CH_4(L/d)=-26.58 × NFC/NDF + 92.70(R~2 = 0.772, P <0.001); CH_4(L/d) = 2.71 × NDFD-2.45 × DMD-0.97 × CPD + 124.46(R~2 = 0.846, P = 0.001). When the sheep grew from 48 to 55 kg BW, the most accurate single-variable and multivariate regression model were shown below: CH_4(L/d) =-57.00 × GE(MJ·kg~(-1)) + 1076.01(R~2 = 0.581, P = 0.002); CH_4/BW~(0.75)(L·kg~(-1)) =-0.01 ×NDFI(g·d~(-1))-0.13 × CPI(g·d~(-1)) + 0.02 × DMI(g·d~(-1)) + 0.84(R~2 = 0.652, P = 0.019). The most accurate single-variable and multivariate regression model in the overall growing period of sheep were shown below: CH_4(L/d)=-26.94 × NFC/NDF + 90.71(R~2 = 0.655, P <0.001); CH_4/BW~(0.75)(L·kg~(-1)) = 0.005 × DNDFI(g·d~(-1)) + 0.011 × DDMI(g·d~(-1))-0.097 × DCPI(g·d~(-1))-4.78(R~2 =0.722, P <0.001). 【Conclusion】 The regression relationships were established for the respective growth periods(25-35 kg and48-55 kg BW) and the overall growth period(25-55 kg BW). The studies showed that the optimal methane prediction factors for meat sheep at different weight were various, and methane production was greatly affected by dietary NFC/NDF, which could be used as a theoretical basis for the evaluation of methane production under the breeding model in China and a reference for the diets of meat sheep.
引文
[1]HTTP://data.stats.gov.cn/easy query.htm?cn=C01.
[2]丁丽娜.中国羊肉市场供求现状及未来趋势研究[D].北京:中国农业大学,2014.DING L N.Research on the current situation and future trend of mutton supply and demand in china[D].Beijing:China Agricultural University,2014.(in Chinese)
[3]闵继胜,胡浩.中国农业生产温室气体排放量的测算.中国人口资源与环境,2012,22(07):21-27.doi:1002-2104(2012)07-0021-07.MING J S,HU H.Calculation of greenhouse gases emission from agricultural production in China.China Population Resources and Environment,2012,22(07):21-27.doi:1002-2104(2012)07-0021-07.(in Chinese)
[4]许贵善,刁其玉,纪守坤,邓凯东,姜成钢,屠焰,刘洁,赵一广,马涛,楼灿.20-35 kg杜寒杂交公羔羊能量需要参数.中国农业科学,2012,45(24):5082-5090.XU G S,DIAO Q Y,JI S K,DENG K D,JIANG C G,TU Y,LIU J,ZHAO Y G,MA T,LOU C.Energy requirement parameters of 20-35kg Dorper and Thin-Tailed Han sheep crossbred male lambs.Scientia Agricultura Sinica,2012,45(24):5082-5090.(in Chinese)
[5]DENG K D,DIAO Q Y,JIANG C G,TU Y,ZHANG N F,LIU J,MA T,ZHAO Y G,XU G S.Energy requirements for maintenance and growth of Dorper crossbred ram lambs.Livestock Science,2012,150(1-3):102-110.
[6]赵一广.肉用绵羊甲烷排放的测定与估测模型的建立[D].北京:中国农业科学院,2012.ZHAO Y G.Measurement and prediction models of methane emissions from sheep[D].Beijing:Chinese Academy of Agricultural Sciences,2012.(in Chinese)
[7]肖怡.三种益生菌对肉羊甲烷排放、物质代谢和瘤胃发酵的影响[D].阿拉尔:塔里木大学,2016.XIAO Y.Effects of three probiotics on methane emission,nutrient metabolism and rumen fermentation in mutton sheep[D].Alar:Tarim University,2016.(in Chinese)
[8]丁静美,成述儒,邓凯东,张明娇,刁其玉,屠焰.不同中性洗涤纤维与非纤维性碳水化合物比值饲粮对肉用绵羊甲烷排放的影响.动物营养学报,2017(3):806-813.doi:10.3969/j.issn.1006-267x.2017.03.010.DING J M,CHENG S R,DENG K D,ZHANG M J,DIAO Q Y,TUY.Effects of different neutral detergent fiber/non-fiberous carbohydrate diets on methane emission of meat sheep.Chinese Journal of Animal Nutrition,2017(3):806-813.doi:10.3969/j.issn.1006-267x.2017.03.010.(in Chinese)
[9]张丽英.饲料分析及饲料质量检测技术[M].中国农业大学出版社,2010.ZHANG L Y.Feed Analysis And Feed Quality Testing Technology[M].China Agriculture Press,2010.(in Chinese)
[10]KRISS M.Quantitative relations of the dry matter of the food consumed,the heat production,the gaseous outgo,and the insensible loss in body weight of cattle.Journal of Agricultural Research,1930,40(3):283-295.
[11]AXELSSON J.The amount of produced methane energy in the European metabolic experiments with adult cattle.Kungliga Lantbrukshogskolans Annaler,1949:404-419.
[12]韩继福,冯仰廉,张晓明,莫放,赵广永,杨雅芳.阉牛不同日粮的纤维消化、瘤胃内VFA对甲烷产生量的影响.中国兽医学报,1997(3):278-280.doi:10.16303/j.cnki.1005-4545.1997.03.023.HAN J F,FENG Y L,ZHANG X M,MO F,ZHAO G Y,YANG Y F.Effects of fiber digestion and VFA in the rumen on the methane production in steers of different type of diets.Chinese Journal of Veterinary Science,1997(3):278-280.doi:10.16303/j.cnki.1005-4545.1997.03.023.(in Chinese)
[13]韩继福,冯仰廉,张晓明,莫放,赵广永,杨雅芳.日粮类型和羊草细度对肉牛瘤胃挥发性脂肪酸比例及能量转化效率的影响.畜牧兽医学报,1998,28(2):97-104.HAN J F,FENG Y L,ZHANG X Y,MO F,ZHAO G Y,YANG Y F.Effects of different diets and different particle sizes of hay on proportion of acetic,propionic and butyric acids in the rumen and on energy conversion in steers feeding.Acta Veterinaria et Zootechnica Sinica,1998,28(2):97-104.(in Chinese)
[14]PELCHEN A,PETERS K J.Methane emissions from sheep.Small Ruminant Research,1998,27(2):137-150.
[15]BLAXTER K L,CLAPPERTON J L.Prediction of the amount of methane produced by ruminants.British Journal of Nutrition,1965,19(4):511-522.doi:10.1079/BJN19650046.
[16]JIAO H,YAN T,WILLS D A,CARSON A F,MCDOWELL D A.Development of prediction models for quantification of total methane emission from enteric fermentation of young Holstein cattle at various ages.Agriculture Ecosystems and Environment,2014,183(183):160-166.doi:10.1016/j.agee.2013.11.004.
[17]毛宏祥,高凤仙,王敏,蒋载阳,张秀敏,龙栋磊,王荣,谭支良.肉牛胃肠道甲烷排放模型估算精度的评估分析.畜牧兽医学报,2017,48(4):690-698.doi:10.11843/j.issn.0366-6964.2017.04.012.MAO H X,GAO F X,WANG M,JIANG Z Y,ZHANG X M,LONGD L,WANG R,TAN Z L.Evaluating the accuracy of models to predict enteric methane emissions in beef cattle.Acta Veterinaria et Zootechnica Sinica,2017,48(4):690-698.doi:10.11843/j.issn.0366-6964.2017.04.012.(in Chinese)
[18]张子仪.从科学发展观谈我国动物营养科研工作的跨越与回归.中国畜牧杂志,2005,41(8):3-5.ZHANG Z Y.A review of the scientific development of modern animal nutrition research in China.Chinese Journal of Animal Science,2005,41(8):3-5.(in Chinese)
[19]罗维,李季,江永红.畜禽集约化养殖对生态环境的影响.中国畜牧杂志,2001,37(5):55-56.LUO W,LI J,JIANG Y J.Effects of intensive culture of livestock and poultry on the ecological environment.Chinese Journal of Animal Science,2001,37(5):55-56.(in Chinese)
[20]BEAUCHEMIN K A,MCGINN S M.Methane emissions from feedlot cattle fed barley or corn diets.Journal of Animal Science,2005,83(3):653-661.doi:10.2527/2005.833653x.
[21]赵一广,刁其玉,刘洁,姜成钢,邓凯东,屠焰.肉羊甲烷排放测定与模型估测.中国农业科学,2012,45(13):2718-2727.doi:10.3864/j.issn.0578-1752.2012.13.016.ZHAO Y G,DIAO Q Y,LIU J,JIANG C G,DENG K D,TU Y.Estimation and regression models of methane emissions from sheep.Scientia Agricultura Sinica,2012,45(13):2718-2727.(in Chinese)doi:10.3864/j.issn.0578-1752.2012.13.016.
[22]JENTSCH W,SCHWEIGEL M,WEISSBACH F,SCHOLZE H,PITROFF W,DERNO M.Methane production in cattle calculated by the nutrient composition of the diet.Archives of Animal Nutrition,2007,61(1):10-19.doi:10.1080/17450390601106580.
[23]VAN SOEST P J,MCCAMMONFELDMAN B,CANNAS A.The feeding and nutrition of small ruminants:application of the Cornell discount system to the feeding of dairy goats and sheep.[C]//Cornell Nutrition Conference for Feed Manufacturers.1994.
[24]PRUSTY S,SONTAKKE U,KUNDU S S.Review:Methane and nitrous oxide emission from livestock manure.African Journal of Biotechnology,2015,13(13):4200-4207.
[25]刘洁,刁其玉,赵一广,姜成钢,李艳玲,屠焰.饲粮不同NFC/NDF对肉用绵羊瘤胃pH、氨态氮和挥发性脂肪酸的影响.动物营养学报,2012,24(6):1069-1077.doi:1006-267X(2012)06-1069-09.LIU J,DIAO Q Y,ZHAO Y G,JIANG C G,LI Y L,TU Y.Effects of dietary NFC/NDF ratios on rumen pH,NH3-N and VFA of meat sheep.Chinese Journal of Animal Nutrition,2012,24(6):1069-1077.doi:1006-267X(2012)06-1069-09.(in Chinese)
[26]JOHNSON K A,JOHNSON D E.Methane emissions from cattle.Journal of Animal Science,1995,73(8):2483-2492.doi:10.2527/1995.7382483x.
[27]RAMIN M,HUHTANEN P.Development of equations for predicting methane emissions from ruminants.Journal of Dairy Science,2013,96(4):2476-2493.doi:10.3168/jds.2012-6095.
[28]HRISTOV A N,KEBREAB E,NIU M,OH J,BANNINK A,BAYAT A R,BOLAND T M,BRITO A F,CASPER D P,CROMPTON L A,DIJKSTRA J,EUGENE M,CARNSWORTHY PC,HAQUE N,HELLWING A L F,HUHTANEN P,KREUZER M,KUHLA B,YU Z.Symposium review:Uncertainties in enteric methane inventories,measurement techniques,and prediction models.Journal of Dairy Science,2018,101(7):6655.doi:10.3168/jds.2017-13536.
[29]APPUHAMY J A D R N,FRANCE J,KEBREAB E.Models for predicting enteric methane emissions from dairy cows in North America,Europe,and Australia and New Zealand.Global Change Biology,2016,22(9):3039-3056.doi:10.1111/gcb.13339.
[30]赵敏孟.杜泊羊生长期能量代谢规律及需要量研究[D].泰安:山东农业大学,2013.ZHAO M M.Study on energy metabolic pattern and energy requirement of growing Dorper sheep[D].Taian:Shandong Agriculture University,2013.(in Chinese)
[2]丁丽娜.中国羊肉市场供求现状及未来趋势研究[D].北京:中国农业大学,2014.DING L N.Research on the current situation and future trend of mutton supply and demand in china[D].Beijing:China Agricultural University,2014.(in Chinese)
[3]闵继胜,胡浩.中国农业生产温室气体排放量的测算.中国人口资源与环境,2012,22(07):21-27.doi:1002-2104(2012)07-0021-07.MING J S,HU H.Calculation of greenhouse gases emission from agricultural production in China.China Population Resources and Environment,2012,22(07):21-27.doi:1002-2104(2012)07-0021-07.(in Chinese)
[4]许贵善,刁其玉,纪守坤,邓凯东,姜成钢,屠焰,刘洁,赵一广,马涛,楼灿.20-35 kg杜寒杂交公羔羊能量需要参数.中国农业科学,2012,45(24):5082-5090.XU G S,DIAO Q Y,JI S K,DENG K D,JIANG C G,TU Y,LIU J,ZHAO Y G,MA T,LOU C.Energy requirement parameters of 20-35kg Dorper and Thin-Tailed Han sheep crossbred male lambs.Scientia Agricultura Sinica,2012,45(24):5082-5090.(in Chinese)
[5]DENG K D,DIAO Q Y,JIANG C G,TU Y,ZHANG N F,LIU J,MA T,ZHAO Y G,XU G S.Energy requirements for maintenance and growth of Dorper crossbred ram lambs.Livestock Science,2012,150(1-3):102-110.
[6]赵一广.肉用绵羊甲烷排放的测定与估测模型的建立[D].北京:中国农业科学院,2012.ZHAO Y G.Measurement and prediction models of methane emissions from sheep[D].Beijing:Chinese Academy of Agricultural Sciences,2012.(in Chinese)
[7]肖怡.三种益生菌对肉羊甲烷排放、物质代谢和瘤胃发酵的影响[D].阿拉尔:塔里木大学,2016.XIAO Y.Effects of three probiotics on methane emission,nutrient metabolism and rumen fermentation in mutton sheep[D].Alar:Tarim University,2016.(in Chinese)
[8]丁静美,成述儒,邓凯东,张明娇,刁其玉,屠焰.不同中性洗涤纤维与非纤维性碳水化合物比值饲粮对肉用绵羊甲烷排放的影响.动物营养学报,2017(3):806-813.doi:10.3969/j.issn.1006-267x.2017.03.010.DING J M,CHENG S R,DENG K D,ZHANG M J,DIAO Q Y,TUY.Effects of different neutral detergent fiber/non-fiberous carbohydrate diets on methane emission of meat sheep.Chinese Journal of Animal Nutrition,2017(3):806-813.doi:10.3969/j.issn.1006-267x.2017.03.010.(in Chinese)
[9]张丽英.饲料分析及饲料质量检测技术[M].中国农业大学出版社,2010.ZHANG L Y.Feed Analysis And Feed Quality Testing Technology[M].China Agriculture Press,2010.(in Chinese)
[10]KRISS M.Quantitative relations of the dry matter of the food consumed,the heat production,the gaseous outgo,and the insensible loss in body weight of cattle.Journal of Agricultural Research,1930,40(3):283-295.
[11]AXELSSON J.The amount of produced methane energy in the European metabolic experiments with adult cattle.Kungliga Lantbrukshogskolans Annaler,1949:404-419.
[12]韩继福,冯仰廉,张晓明,莫放,赵广永,杨雅芳.阉牛不同日粮的纤维消化、瘤胃内VFA对甲烷产生量的影响.中国兽医学报,1997(3):278-280.doi:10.16303/j.cnki.1005-4545.1997.03.023.HAN J F,FENG Y L,ZHANG X M,MO F,ZHAO G Y,YANG Y F.Effects of fiber digestion and VFA in the rumen on the methane production in steers of different type of diets.Chinese Journal of Veterinary Science,1997(3):278-280.doi:10.16303/j.cnki.1005-4545.1997.03.023.(in Chinese)
[13]韩继福,冯仰廉,张晓明,莫放,赵广永,杨雅芳.日粮类型和羊草细度对肉牛瘤胃挥发性脂肪酸比例及能量转化效率的影响.畜牧兽医学报,1998,28(2):97-104.HAN J F,FENG Y L,ZHANG X Y,MO F,ZHAO G Y,YANG Y F.Effects of different diets and different particle sizes of hay on proportion of acetic,propionic and butyric acids in the rumen and on energy conversion in steers feeding.Acta Veterinaria et Zootechnica Sinica,1998,28(2):97-104.(in Chinese)
[14]PELCHEN A,PETERS K J.Methane emissions from sheep.Small Ruminant Research,1998,27(2):137-150.
[15]BLAXTER K L,CLAPPERTON J L.Prediction of the amount of methane produced by ruminants.British Journal of Nutrition,1965,19(4):511-522.doi:10.1079/BJN19650046.
[16]JIAO H,YAN T,WILLS D A,CARSON A F,MCDOWELL D A.Development of prediction models for quantification of total methane emission from enteric fermentation of young Holstein cattle at various ages.Agriculture Ecosystems and Environment,2014,183(183):160-166.doi:10.1016/j.agee.2013.11.004.
[17]毛宏祥,高凤仙,王敏,蒋载阳,张秀敏,龙栋磊,王荣,谭支良.肉牛胃肠道甲烷排放模型估算精度的评估分析.畜牧兽医学报,2017,48(4):690-698.doi:10.11843/j.issn.0366-6964.2017.04.012.MAO H X,GAO F X,WANG M,JIANG Z Y,ZHANG X M,LONGD L,WANG R,TAN Z L.Evaluating the accuracy of models to predict enteric methane emissions in beef cattle.Acta Veterinaria et Zootechnica Sinica,2017,48(4):690-698.doi:10.11843/j.issn.0366-6964.2017.04.012.(in Chinese)
[18]张子仪.从科学发展观谈我国动物营养科研工作的跨越与回归.中国畜牧杂志,2005,41(8):3-5.ZHANG Z Y.A review of the scientific development of modern animal nutrition research in China.Chinese Journal of Animal Science,2005,41(8):3-5.(in Chinese)
[19]罗维,李季,江永红.畜禽集约化养殖对生态环境的影响.中国畜牧杂志,2001,37(5):55-56.LUO W,LI J,JIANG Y J.Effects of intensive culture of livestock and poultry on the ecological environment.Chinese Journal of Animal Science,2001,37(5):55-56.(in Chinese)
[20]BEAUCHEMIN K A,MCGINN S M.Methane emissions from feedlot cattle fed barley or corn diets.Journal of Animal Science,2005,83(3):653-661.doi:10.2527/2005.833653x.
[21]赵一广,刁其玉,刘洁,姜成钢,邓凯东,屠焰.肉羊甲烷排放测定与模型估测.中国农业科学,2012,45(13):2718-2727.doi:10.3864/j.issn.0578-1752.2012.13.016.ZHAO Y G,DIAO Q Y,LIU J,JIANG C G,DENG K D,TU Y.Estimation and regression models of methane emissions from sheep.Scientia Agricultura Sinica,2012,45(13):2718-2727.(in Chinese)doi:10.3864/j.issn.0578-1752.2012.13.016.
[22]JENTSCH W,SCHWEIGEL M,WEISSBACH F,SCHOLZE H,PITROFF W,DERNO M.Methane production in cattle calculated by the nutrient composition of the diet.Archives of Animal Nutrition,2007,61(1):10-19.doi:10.1080/17450390601106580.
[23]VAN SOEST P J,MCCAMMONFELDMAN B,CANNAS A.The feeding and nutrition of small ruminants:application of the Cornell discount system to the feeding of dairy goats and sheep.[C]//Cornell Nutrition Conference for Feed Manufacturers.1994.
[24]PRUSTY S,SONTAKKE U,KUNDU S S.Review:Methane and nitrous oxide emission from livestock manure.African Journal of Biotechnology,2015,13(13):4200-4207.
[25]刘洁,刁其玉,赵一广,姜成钢,李艳玲,屠焰.饲粮不同NFC/NDF对肉用绵羊瘤胃pH、氨态氮和挥发性脂肪酸的影响.动物营养学报,2012,24(6):1069-1077.doi:1006-267X(2012)06-1069-09.LIU J,DIAO Q Y,ZHAO Y G,JIANG C G,LI Y L,TU Y.Effects of dietary NFC/NDF ratios on rumen pH,NH3-N and VFA of meat sheep.Chinese Journal of Animal Nutrition,2012,24(6):1069-1077.doi:1006-267X(2012)06-1069-09.(in Chinese)
[26]JOHNSON K A,JOHNSON D E.Methane emissions from cattle.Journal of Animal Science,1995,73(8):2483-2492.doi:10.2527/1995.7382483x.
[27]RAMIN M,HUHTANEN P.Development of equations for predicting methane emissions from ruminants.Journal of Dairy Science,2013,96(4):2476-2493.doi:10.3168/jds.2012-6095.
[28]HRISTOV A N,KEBREAB E,NIU M,OH J,BANNINK A,BAYAT A R,BOLAND T M,BRITO A F,CASPER D P,CROMPTON L A,DIJKSTRA J,EUGENE M,CARNSWORTHY PC,HAQUE N,HELLWING A L F,HUHTANEN P,KREUZER M,KUHLA B,YU Z.Symposium review:Uncertainties in enteric methane inventories,measurement techniques,and prediction models.Journal of Dairy Science,2018,101(7):6655.doi:10.3168/jds.2017-13536.
[29]APPUHAMY J A D R N,FRANCE J,KEBREAB E.Models for predicting enteric methane emissions from dairy cows in North America,Europe,and Australia and New Zealand.Global Change Biology,2016,22(9):3039-3056.doi:10.1111/gcb.13339.
[30]赵敏孟.杜泊羊生长期能量代谢规律及需要量研究[D].泰安:山东农业大学,2013.ZHAO M M.Study on energy metabolic pattern and energy requirement of growing Dorper sheep[D].Taian:Shandong Agriculture University,2013.(in Chinese)