高原鼢鼠越冬食物选择与营养成分的关系

Relationship between overwintering preference and nutritional content of the foods of plateau zokor(Eospalax baileyi)

为了解高原鼢鼠在越冬期的食物选择与营养成分之间的关系,采集了67个高原鼢鼠的冬季粮仓及环境样方,分析高原鼢鼠对每一种植物的选择指数,将其分成3种食物类型:喜食、可变和不喜食。通过测定每一种植物的粗蛋白、粗纤维、水溶性糖和粗灰分的含量,比较分析了营养成分含量在3种食物类型间的差异,及其与各种植物选择指数的相关关系。结果显示,高原鼢鼠储存的食物种类多达67种,本文选取含量较高且样本量大于5的39种植物(占粮仓和样方总生物量的99%以上,其中喜食12种、可变16种、不喜食11种)进行分析。在3种食物类型之间,粗蛋白、粗纤维和水溶性糖含量均有极显著差异(P<0.001),粗灰分含量则无明显差异(P=0.800)。喜食和可变类型的粗蛋白和水溶性糖含量显著高于不喜食类型(P<0.01);喜食和可变类型的粗纤维含量则显著低于不喜食类型(P<0.01);喜食和可变类型之间这3个指标差异都不显著(P>0.05)。Spearman相关分析显示,粗蛋白(R=0.547,P<0.001)和水溶性糖(R=0.617,P<0.001)含量与选择指数显著正相关,粗纤维与选择指数显著负相关(R=-0.707,P<0.001),粗灰分与选择指数则无显著相关关系(R=0.032,P=0.846)。结果表明,高原鼢鼠总体上偏好粗蛋白和水溶性糖含量高、粗纤维含量低的植物,对无机盐的含量则不敏感。

In the current paper we sampled plants from winter caches and nearby vicinities of 67 burrow systems of the plateau zokor（ Eospalax baileyi）. We then calculated the electivity index（ EI） of each of the food items based on their relative biomass and divided them into three preference types based on the 95% confidence limit of the mean EI with bootstrap methods：（ 1） preferred： 95% confidence lower limit 〉 0;（ 2） changeable： 95% confidence lower limit ≤0 and95% confidence upper limit≥0; and（ 3） rejected： 95% confidence upper limit 〈 0. Subsequently,we measured the content of crude protein,crude fiber,crude water-soluble sugars,and crude ash of these food items and then compared them among the three preference types and further tested the correlations between the mean EI and each of these content levels.A total of 67 food items were identified from the caches,of which 39（ preferred,12 items; changeable,16 items; rejected,11 items） were found in more than five burrowing systems,constituting over 99% of the total biomass that we sampled. The contents of crude protein,crude fiber,and crude water-soluble sugars（ but not crude ash） differed significantly among the three types（ P 〈 0. 001）. The preferred and changeable types had significantly higher contents of crude protein and crude water-soluble sugars than the rejected types（ P 〈 0. 01）. Furthermore,the preferred and changeable types were found to have a significantly lower content of crude fiber as compared to the rejected types（ P 〈 0. 01）. However,the three content levels were not significantly different between the preferred and changeable types（ P 〉 0. 05）. Spearman correlation showed that the contents of crude protein（ R = 0. 547,P 〈 0. 001） and crude water-soluble sugars（ R = 0. 617,P 〈0. 001） both were significantly and positively correlated with EI while the content of crude fiber was significantly and nega-tively correlated（ R =- 0. 707,P 〈 0. 001）. The content of crude ash was not significantly correlated with EI（ R =0. 032,P = 0. 846）. Taken together,our results indicate that plateau zokor prefer food items containing higher levels of protein,more water-soluble sugars,and less fiber,but are apparently not sensitive to mineral content.