链烷技术估测典型草原放牧牛食性食量方法研究

Estimation of Diet Composition and Herbage Intake of Grazing Cows using n-Alkane Technique in Inner Mongolia Typical Steppes

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。

In order to probe into the application of n-alkanes as markers for estimating diet composition and herbage intake of free grazing herbivores in rangeland,an experiment was carried out in summer and autumn 2004 at the Inner Mongolia Grassland Ecosystem Research Station of Chinese Academy of Sciences.Four cows selected from a group of 4 years old were grazed in rangeland from 1 July to 13 August to study their diet composition and herbage intake during two grazing periods.Artificial YC capsules were dosed in the beginning of each period.The samples of herbage and feces were collected daily for 7 days and dried for n-alkane concentration analysis using gas chromatography to estimate the feces output,diet composition,and herbage intake of cows.The results show that the plant species were eaten by grazing cows were similar,the diet composition were different in grazing seasons,and their herbage intake significantly increased with the proceeding of grazing seasons（P〈0.05）,but the feces output did not differ significantly（P〉0.05）.In conclusion,n-alkane technique could provide an estimation of feces output,diet composition and herbage intake of grazing cows,and grazing seasons had more effect on their herbage intake.In order to improve n-alkane technique,other methods should be compared with n-alkane technique for the estimation of diet composition and herbage intake of free grazing herbivores in species mixed rangelands.