Skördesystem i vall, skördens storlek ochfoderkvalitet
The choice of harvest date for leys is one of the most important factors affecting the size and quality of the harvest. An early harvest gives a high nutritive value while a late harvest gives larger quantity. Today?s aim to produce high nutritive leys gives early harvest dates both in primary growth and regrowth in northern part of Sweden. The consequence is a growth in the autumn, a "third harvest".The aim of this master thesis was to study the effects of different harvesting systems and their effect on size, feed quality, wintering and economy for conditions in the northern part of Sweden. How different amount of litter in the spring affects the silage quality has also been studied.On the research station Röbäcksdalen in Umeå, a field trial was started in an existing first year ley in 2006. The ley consisted of red clover, timothy and meadow fescue and was studied under three years (2006-2008). During the three years of the trial the ley was harvested according to three systems. One system with two harvests with high nutritive quality, one with three harvests and one with two harvests where the harvesting dates was somewhat later than in the first system. The quality of the silage, microbial and hygienic, was studied in a fermentation study where green forage from the two first systems was used. The quality of the forage in the different systems was compared from feeding plans calculated in the optimisation software NorFor. Also, an economic evaluation was done.The highest yielding system over the three years was the three-harvest system. However, a marked decline in the third year indicates that the system has a problem with persistence. The fermentation study showed that the hygienic status of silage with large amount of litter didn?t differ from the silage without the large litter amount. The calculations of the feeding plans showed that the harvest system with early primary growth harvest gave less expensive feeding rations with less amount of concentrate. The economic evaluation showed that the system with three harvests combined low optimizing cost for the feeding plan with high yielding leys.