Kuntz Regina, Kubalek Christina, Ruf Thomas, Tataruch Frieda, Arnold Walter
Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Savoyenstrasse 1, 1160 Vienna, Austria.
J Exp Biol. 2006 Nov;209(Pt 22):4557-65. doi: 10.1242/jeb.02535.
Large ruminants respond to changing plant phenology during winter by decreasing voluntary food intake, increasing gut passage time and utilizing body fat reserves. It is uncertain, however, how other large mammals with a non-ruminant digestive physiology cope with winter forage conditions. Therefore, we investigated seasonality of energy intake in a large herbivorous wild mammal, the Przewalski horse (Equus ferus przewalskii). Throughout all seasons we used the n-alkane method to measure daily dry matter intake (DMI), diet composition and digestion, and determined an index of gut passage time in horses living under close to natural conditions. DMI correlated positively with its content of crude protein and nitrogen-free extract. Independent of these effects, DMI further varied seasonally with a peak in autumn and a nadir in late winter. Fluctuations of DMI corresponded to the annual change in body condition, which decreased during winter while energy reserves were depleted, and increased during the fattening period. Gut passage time varied in the course of the year and was longer during winter when the diet was high in crude fibre. Nevertheless, changes in gut passage time occurred rather independently of changes in forage composition and DMI, suggesting endogenous control for timely adaption of the digestive strategy to meet predictable changes in forage quality.
大型反刍动物在冬季通过减少自愿采食量、增加肠道通过时间和利用体脂储备来应对植物物候变化。然而，其他具有非反刍消化生理的大型哺乳动物如何应对冬季草料条件尚不确定。因此，我们研究了大型草食性野生哺乳动物普氏野马（Equus ferus przewalskii）能量摄入的季节性变化。在所有季节中，我们使用正构烷烃法测量每日干物质摄入量（DMI）、饮食组成和消化情况，并确定了生活在接近自然条件下的马匹的肠道通过时间指数。DMI与其粗蛋白和无氮浸出物含量呈正相关。除了这些影响外，DMI还随季节变化，秋季达到峰值，冬末降至最低点。DMI的波动与身体状况的年度变化相对应，冬季身体状况下降，能量储备耗尽，育肥期则增加。肠道通过时间在一年中有所变化，冬季膳食纤维含量高时较长。然而，肠道通过时间的变化与草料组成和DMI的变化相当独立，这表明存在内源性控制，以便及时调整消化策略以适应草料质量的可预测变化。
