饱和链烷技术测定绵羊食性食量精确性研究

【目的】验证饱和链烷技术测定家畜食性和食量的精确性，确定绵羊粪便中链烷的回收率。【方法】于2004年秋季在中国科学院内蒙古草原生态系统定位研究站用不同放牧演替阶段的优势植物羊草（Leymus chinensis）、糙隐子草（Cleistogenes squarrosa）和冷蒿（Artemisia frigida）按一定比例混合组成日粮，饲喂9只2岁羯羊，每只羊投喂一粒QSM胶囊，试验期内每天记录绵羊实际牧草采食量、采食成分和排粪量，利用气相色谱分析牧草和粪样的链烷含量，应用链烷技术测定绵羊的排粪量、不同牧草采食比例和总干物质采食量，并与实际值进行比较。【结果】3种牧草链烷模式存在种间差异；绵羊粪便中链烷的回收率随链烷长度的增加而线性增加；绵羊排粪量测定值与实际值存在极显著的正相关（P < 0.01，r = 0.9994）；绵羊采食羊草、糙隐子草和冷蒿比例的测定值与实际值存在极显著(P < 0.01)正相关，相关系数分别为0.9913、0.9864和0.9999；绵羊干物质采食量用C33∶C32和C31∶C32比值测定的值分别比实际值低4％(±1.3％)和7％(±1.3％)，但差异不显著(P > 0.05)。【结论】饱和链烷技术可以精确测定典型草原绵羊的排粪量、食物组成和采食量。

Study on the Accuracy and Precision of n-Alkanes as Markers for Estimation of Diet Composition and Herbage Intake of Sheep

【Objective】An experiment was carried out to determine the accuracy and precision of n-alkanes as markers for estimation of feces output, diet composition and herbage intake of sheep, and measure fecal recoveries of n-alkanes in sheep, 【Method】The experiment was carried out at the Inner Mongolia Grassland Ecosystem Research Station of the Chinese Academy of Sciences in autumn 2004. Nine wethers selected from a group at 2-years-old of age were fed with fresh mixtures of Leymus chinensis (30%), Cleistogenes squarrosa (20%) and Artemisia frigida (50%) in known proportions and amounts for 14 days. Artificial QSM capsules were dosed during the experiment. The samples of herbage and feces were collected daily for 7 days and dried for analysing the n-alkane concentration by a gas chromatography. 【Result】The results showed that there was a difference in concentration of n-alkanes among 3 species forages, and fecal recoveries of n-alkanes linear increased with increasing carbon chain lengths. There were significant correlations (P < 0.01) between estimated feces output (r = 0.9994), dietary composition of L. chinensis (r = 0.9913), C. squarrosa (r = 0.9864), A. frigida (r = 0.9999) and herbage intake using n-alkane technique and the actual values. Estimated intakes were 4% (±1.3％) and 7% (±1.3%) lower than the actual intake by sheep based on C33:C32 and C31:C32 n-alkane ratios, respectively, but were not differ significantly (P > 0.05). 【Conclusion】 In conclusion, n-alkane technique can provide an accurate and precise estimation of feces output, diet composition and herbage intake of sheep.