Utilisation de prairies permanentes et temporaires par un troupeau de vaches allaitantes en zone de demi-montagne humide

Utilization of permanent pastures and of leys by a herd of suckling cows in a semi-mountainous region under a wet climate

The INRA Estate at Marcenat (Cantal), located at an altitude of 1000 m on a plateau of volcanic origin, has served for many studies on grazing systems from 1973 to 1979. Four types of rotational grazing could thus be compared during years with very contrasted weather conditions ; they differ by the stocking-rates (1.4 to 1.8 couples/hectare), by the kind of grassland (permanent pastures or leys), and by the proportion of forage-producing area added in Summer to the grazed area.In each of the 4 cases, the utilization of the basal area and of the additional area is described in detail : control of the flower-heads, of the ungrazed patches, according to the speed of rotation and the stocking-rate. The addition of an area of leys increases both the amount of forage stored for the Winter and the stocking under grazing.The intensification of a permanent pasture (by mowing, and then grazing, with an adequate fertilization) makes it possible to increase the stockingrate, but the area subjected to mowing (which determines the level of forage in store for the Winter) is much more sensitive to the variations of the weather conditions than in the traditional system.