Factors affecting digestibility of temperate forages from seminatural grasslands: a review

To indicate possibilities for the use of forages from seminatural grasslands in ruminant production systems, a literature study to describe the nutritive value of those forages was carried out. In species-rich grasslands, the digestibility of forages is usually lower than the digestibility of forages produced by grasslands used for intensive production. There is also more variation within a species-rich sward, because of different stages of maturity of the individual species and because of likely variations in digestibility among forage species independent of stage of maturity. Moreover, the presence of dicotyledonous species may have a positive or negative effect on digestibility. In forages from seminatural grasslands, the relationship between chemical composition and digestibility differs from that of Lolium perenne, which is often used as a research standard. Therefore, predictions of the digestibility of species-rich forage can be inaccurate. The relationship between in vivo and in vitro digestibility may also be different from the relationship that is common for L. perenne. In some cases, the in vivo digestibility is higher than the in vitro value, as calibrations are based on L. perenne. Therefore, the quality of forages from seminatural grasslands might be higher than predicted, and this may increase the scope for practical use of this kind of forage in ruminant nutrition systems.