1Les Haras Nationaux, Direction des Connaissances, Station Expérimentale des Haras Nationaux, 19370 Chamberet, France.
Animal. 2010 Mar;4(3):480-5. doi: 10.1017/S1751731109991133.
The spatial heterogeneity of grasslands determines the abundance and quality of food resources for grazing animals. As plants mature, they increase in mass, which allows greater instantaneous intake rates, but the cell wall concentrations increase too, reducing diet quality. In ruminants, daily intake rates are often constrained by the time needed for the ingesta to pass through the rumen, which is influenced by the rate of digestion. It has been suggested that the digestive constraint should have much less effect on hindgut fermenters such as equids. Horses play an increasing role in the management of grasslands in Europe, but the data on the influence of the heterogeneity of the vegetation on their daily intake and foraging behaviour are sparse. We report here the results of a preliminary study concerning the effects of sward structure on nutrient assimilation and the use of patches of different heights by horses grazing successively a short immature, a tall mature and a heterogeneous pastures (with short and tall swards). Daily nutrient assimilation was higher in the heterogeneous pasture compared to the short (+35%) and the tall (+55%) ones. The digestive constraints may have limited voluntary intake by horses on the tall swards. In the heterogeneous pasture, the mean height used for feeding (6 to 7 cm) by horses was intermediate between the heights used in the short (4 to 5 cm) and tall pastures (22 to 23 cm), and the animals may thus have benefited from both short swards of high quality and tall swards offering a higher instantaneous intake rate.
草原的空间异质性决定了放牧动物的食物资源的丰富度和质量。随着植物的成熟，它们的质量增加，允许更大的瞬时摄入率，但细胞壁浓度也增加，降低了饮食质量。在反刍动物中，每日摄入量通常受到食糜通过瘤胃所需时间的限制，而这又受到消化速度的影响。有人认为，消化限制对反刍动物如马等后肠发酵者的影响应该小得多。马在欧洲草原管理中扮演着越来越重要的角色，但关于植被异质性对其日摄入量和觅食行为的影响的数据却很少。我们在这里报告了一项初步研究的结果，该研究涉及到草丛结构对养分吸收的影响，以及马连续放牧短而不成熟、高而成熟和异质化（有短而高的草丛）牧场时对不同高度斑块的利用。与短（+35%）和高（+55%）草丛相比，在异质化草原上，马的每日养分吸收更高。消化限制可能限制了马在高草丛中的自愿摄入量。在异质化的草原上，马用于进食的平均高度（6 到 7 厘米）在短（4 到 5 厘米）和高（22 到 23 厘米）草丛之间，因此，动物可能从高质量的短草丛和提供更高瞬时摄入量的高草丛中受益。
