PASTURE MANAGEMENT WITH DAIRY-COWS WITHOU T N FERTILIZATION

In a dairy cattle pasture trial, conventional pasture farming using 26 0 kg N fertilizer per hectare was compared with an alternative form wi thout any N fertilizer. The use of fe concentrated feed was reduced to a minimum in both cases. The effects on the fodder supply and quality , animal productivity, animal behaviour and N balance of the pasture a rea were studied. It was possible to demonstrate that, despite the fac t that no nitrogen fertilizer was used, it is possible to keep cows mi lk production at a high level if the stocking rate is matched to the y ield and a quality-oriented pasture system is maintained. By improving pasture management, it was possible to reduce the average milk produc tion differences between the two trials from 2.0 kg FCM/animal/day in the first trial stage to 0.8 kg FCM/animal/day in the second year. In the third year the same milk production could be achieved. However, wi thout N fertilisation, it was difficult to achieve equivalent animal p roduction levels on the previously intensively farmed ryegrass pasture s without a subtantial white clover content. The reason for this was t he reduced quantity of fe:ed value which occurred where no fertilizer was used on a non-leguminous turf despite the same pasture management; this was reflected in the lower digestibility and lower energy conten t of the feed. This reduced feed value was not detectable from the cru de fibre content. On the other side by not using fertilizer, it was po ssible to reduce the crude protein excesses and nitrate contents in th e pasture feed, which removed one burden on metabolism and thus had po sitive effects with regard to animal health. Animal behaviour was not adversely affected by the lack of N fertilisation. The slightly increa sed locomotion and slightly longer rumination time were not significan t in terms of extra energy requirement. The results of the study confi rm that by not using fertilizers and by an extremely low N input via c oncentrated feed, the N surplus and thus environmental pollution can b e substantially reduced.