A four-year comparison of two organic dairy systems

Two organic systems were studied, the first based on self-sufficiency (SS) and the feeding of high-forage diets, and the second on purchased concentrates (PC) and maximising milk output. The growing of both concentrate and forage feeds in the SS system reduced the stocking density. Feeding high-forage diets increased the proportion of milk produced from forage but decreased the energy concentration of the ration, leading to lower milk persistency, reduced milk protein in early lactation and reduced pregnancy rates. In the PC system importing feed increased the stocking density but also increased the ‘farm-gate’ nutrient surpluses.