Influence of organic farming on energy and protein supply of dairy cows - Model calculations on the basis of new legal rules

The regulation (EG) 1804/1999 standardised the feeding norms on organic far ms for all EU member countries. With dairy cattle the restrictions in the f eeding of concentrate as well as concentrate components are important. On t he basis of model calculations the consequences on the planning of ration a nd nutrient supply at different milk yield potential and forage ration type s and qualities (forage-high quality, forage-low quality;forage + 20 % corn silage-good quality) have been investigated. In organic farms the quality of forage is of great consequence because the need for expensive concentrate decreases and the maximum of the tolerated c oncentrate level is reached at a higher milk yield. On an average the milk yield decreases by about 1000 kg per lactation if the energy concentration of forage decreases by 0.5 MJ NEL/kg DM. With an energy concentration of fo rage of 5.8 MJ NEL/kg DM a milk yield of about 7.500 kg can be achieved wit hout exceeding the tolerated maximum of energy under supply (-1300 MJ NEL). The supply of utilisable protein (nXP) is dependent on the energy intake. A high energy supply guarantees the supply of utilisable protein up to 6.600 -6.800 kg milk yield. In this case the feeding of protein rich concentrate is most important to cover up the N-requirements in the rumen. The nXP requ irements can be met up to a milk yield between 7,500 and 8,000 kg, without exceeding the tolerated maximum of nXP under supply. With increasing milk y ield the importance of slowly degradable protein concentrate components wit h a high energy content increases.