Extensification en élevage ovin par agrandissement des surfaces. Adaptation de la gestion des prairies

Extensification of sheep production systems through farm area enlargement : herbage management

In areas of agricultural decline, the enlargement of farm areas give the opportunity of having more extensive production systems, which maintenance of flock productivity, provided the available extra areas are well integrated and utilized. A long-term trial (5 years) was set up on an INRA experimental unit in the Massif central hills (France), at medium altitude (800 m), with the aim of trying to build a low-cost system taking advantage of extra herbage resources. To this end, the technical and economical results of an enlarged and a control farm (with stocking rates respectively 1.2 and 0.85 LU/ha) were compared. The economical balance over the whole experimental period, as shown in a previous paper, was in favour of the extensive system.
The present paper shows the management practices adopted to integrate the extra resources, with their effects on the floristic composition, production and utilization of herbage. On the enlarged farm, costs were decreased by reducing nitrogen inputs (–70%) at the whole-system scale (and no N on a few plots where white clover was expected), by using hay rather than silage for conservation, and by extending the length of the grazing period. Control of excess spring grass by early cuts and maintenance of a larger volume of conserved forage to facilitate carry-over were two new rules adopted under the enlarged system to secure quality and availability of forage throughout the year and from year to year. In this way, herbage quality was maintained ; white clover increased from the third year onwards, particularly on the deeper soils ; the decrease in lamb growth, despite less consumption of concentrate. This approach to extensification could be adopted for a large part of the grassland area at medium altitudes.