On the basis of calculations the effects of dairy cow life weight on feed efficiency and
concentrate demand for a whole lactation have been investigated. The results show,
that the annual milk yield is not a sufficient efficiency indicator because efficiency is
strongly affected by the life weight. To compensate for an increase in life weight of 100
kg the annual milk yield of dairy cows must increase per 12-13 % to achieve the same
feed conversion efficiency (kg ECM/kg DM, kg ECM/MJ NEL). Given this, heavier
cows need a higher proportion of concentrate in the annual ration because feed intake
increases to a lower extent than the energy requirements. We conclude that in the
cattle breeding efficiency parameters have to be considered and that for organic dairy
farms heavy and high yielding dairy cows can not be recommended
