Nutritional characteristics of cattle forage plants in the eutrophic nature reserve Oostvaardersplassen, Netherlands.

Abstract

The nutritional value of the main cattle forage plants was studied in the terrestrial part of the eutrophic wetland the Oostvaardersplassen, the Netherlands. The digestible organic matter (DOM) content and the chemical composition of the forage classes grasses, reed, forbs and browse varied seasonally. The DOM content of all forage classes showed a decrease from spring to winter as usual. However, the assumed minimum energy content for cattle mainte­ nance (approximately 450 g DOM kg -1 dry matter) was reached at different moments in the different forage classes. Reed reached it in autumn, grasses in winter, forbs (living parts) re­ mained the entire year above this level and browse remained the entire year below this level. Grazing delayed the maturation of Poa trivialis, reed ( Phragmites australis) and the impor­ tant forb Urtica dioica. The protein, K, Ca, P, Cu content of the four forage classes exceeded the cattle maintenance levels for these nutrients the whole year. The Na and Mg content of grasses, reed and browse were marginal in some periods of the year. Due to their high miner­ al contents, the forbs were an important mineral source in cattle diets. When compared with literature data from oligotrophic and mesotrophic habitats, the studied Poa-Phragmites eu­ trophic habitat offers comparable feed quality in spring, summer and autumn, but is inferior in winter.