Designing organic dairy systems based on agronomic principles

Abstract

his work aimed at designing environmental friendly farming systems and agricultural practices. We assumed that designing farming systems and territories according to the natural properties of land, taking into account their heterogeneity, assures their environmental sustainability. Thus, two organic dairy systems have been prototyped, since 2005, on the experimental farm of INRA ASTER-Mirecourt. The experimental farm is seen as a self-sufficient territory in which systems might have mutual and equivalent exchanges. The designed systems have different objectives : a grazing system (GS) aimed at maximising pasture in the cow’s diet (40 dairy cows and their replacement heifers on permanent grasslands (78 ha)), and a Mixed Crop Dairy System (MCDS) aimed at closing the nutrient cycles (60 dairy cows and their replacement heifers on permanent grasslands (50 ha) and cropping systems (110 ha)). From 2005 to 2008, the 2 systems have maintained good milking performances : they sold from 83 to 98% of their milk quota. Reproduction performances of the GS system were low in 2005 and 2006, generating a decrease of dairy cow herd size. The low stocking rate and the important yields of grass have gene-rated an excess of forage. The forage and straw budgets of the MCDS were quite short and consequently difficult to balance : they were secured by adjusting herd diets and size. Managing these self-sufficient systems makes it necessary to pay more attention to their resource behaviour. Changes in the dynamics of grass growth throughout the year and reproduction rates of animals are some examples of chan-ging behaviours of resources that might be important to integrate in the system management. Resource behaviour is being better and better integrated in the management of the two prototypes.