Kvalitetsförändringar hos rajsvingelsorterna Hykor, Perun och Paulita under första skörd

Sammanfattning: Today, high-yielding leys of good quality are a must for Swedish dairy and beef enterprises if they are to become profitable. Thus, it is of interest to evaluate the quality of the recently released high-yielding Festulolium hybrids ((Festulolium braunii (K.Rich.) A.Camus). The aim of this project was to determine at what phenological stage three different Festulolium hybrids should be cut in order to get the highest nutritional value. The hybrids studied were Hykor, Perun and Paulita. In the study I also investigated if leaf proportion of the crop could be useful for predictions of the crop content of metabolizable energy. The cultivars were grown in plots within a variety trial with ryegrasses. The trial was located at Rådde in the south-west of Sweden. Each cultivar was replicated three times. The studied cultivars were harvested at the 25th of May, 2nd and 7th of June. Four samples, each with an area of 0.03 m2, were cut at ground level within each of the plots. The phenological stage of the grasses was visually scored in the field. A detailed analysis of the phenological stage was also done in the lab on the basis of 100 randomly collected tillers. The same sample was thereafter separated into leaves and straw (including leaf sheaths), dried, weighed and analysed for metabolisable energy, protein, NDF, iNDF and ash contents. The result showed that for Hykor the visually scored phenological stage agreed poorly with the results from the detailed analysis performed in the lab, especially at late reproductive stages. Perun and Paulita had a good agreement between the visually scored phonological stage and the detailed analysis. The chemical analyses showed that energy and protein contents decreased and NDF and iNDF contents increased with the phenological development of the crop. It was concluded that the two hybrids Perun and Paulita must be harvested at the beginning of heading in order to get a high nutritional value of the crop. The hybrid Hykor must be harvested before the phenological stage, beginning of heading, to get a high nutritional value. The study also shows that the genetical background of the hybrid affects the nutritional value more than leaf proportion does.