Changes in nitrogen and carbohydrate fractions associated with the field drying of vetch (Vicia sativa L.)

A field study was conducted to determine the changes occurring in the nitrogen and carbohydrate fractions of vetch herbage during field drying in the haymaking process. Plant materials were whole aerial parts and leaf and stem components. Samples were collected just before and after field drying and analysed for crude protein, degradable protein, non-protein nitrogen, acid detergent insoluble nitrogen, total non-structural carbohydrates, neutral and acid detergent fibres, cellulose and lignin. With the exception of non-protein nitrogen, which increased, the nitrogen fractions showed non-significant changes during the field drying of herbage. The main changes in the carbohydrate fraction was a significant decrease (P < 0.05) in the amount of total non-structural carbohydrates, which resulted in losses that ranged from 34 g kg−1 to 18 g kg−1, depending on the year, expressed as losses of dry matter. Cell-wall constituents were very little affected. The chemical changes followed a similar pattern in both the leaf and stem components.