Autonomie alimentaire et bilans minéraux des élevages bovins laitiers selon les systèmes de production

Food self-sufficiency and mineral balances on dairy cattle farms according to production systems

Food self-sufficiency is aimed at for technical and economical reasons, and also for the brand image of products. An analysis based on data by 'Réseaux d'Elevage' (a network of animal farms) made it possible to characterize feed self-sufficiency on dairy cattle farms and the corresponding mineral balances according to their production systems. Feed self-sufficiency is defined as the ratio between the feed produced and the feed consumed. It is then sub-divided according to the kind of feed (total diet, forages and concentrates) and to feed composition (dry matter DM, Feed Units for milk UFL, protein). For the farms as a whole, global self-sufficiency is large (86.2% for DM, 71.4% for protein), but as regards concentrates, it is much smaller (32.1% for DM, 20.3% for protein). On an average, the mineral balances amount to +53 kg N, +15 kg P2O5, and +28 kg K2O per hectare utilized farm area. P and K balances vary concurrently, but independently of the N balance, which is negatively linked to protein self-sufficiency. As regards both self-sufficiency and mineral balances, organic farming systems stand sharply apart. Systems that use much maize are less self-sufficient, but there is little difference between the systems based on grass and those that use a little maize. Self-sufficiency goes down when the level of intensification rises.