The persistence of English ryegrass cultivars (Lolium perenne L.) in binary mixtures with white clover (Trifolium repens L.) under grazing

The persistence of highly productive forage species in pastures is essential to maximize economic returns from grazing livestock. However, most forage cultivars are neither selected nor evaluated under grazing. To test the persistence of ryegrass (Lolium perenne L.) cultivars under grazing, a five-year plot trial was conducted on commercial dairy farms located in different climatic conditions in Switzerland. Plots were arranged in a randomized, complete block design with three replicates and sown in autumn 2007 and spring 2008 in binary mixtures with white clover (Trifolium repens L). The relative frequency of the perennial ryegrass cultivars was evaluated in 2008, 2009 and 2012 to determine their long-term tolerance to grazing. Significant interactions between both site and cultivar and site and years were found, revealing the importance of the site and its management for the performance of the cultivars. The persistence, as determined by the relative frequencies of the ryegrass cultivars tested, corresponded in the short-term (second and third years) to the rankings of the official variety trials but differed for the long-term observation (in the fifth year). This suggests the need for additional long-term observations under grazing conditions as an extension of the official variety recommendations for cost-efficient, pasture-based livestock production.