Comparison of Marshall and Surrey ryegrass for continuous and rotational grazing.

'Surrey' ryegrass (Lolium multiflorum Lam.) has produced well in clipping yield trials across Louisiana, but yield trials do not always predict how well the forage supports performance under grazing conditions. This trial compared Surrey ryegrass with 'Marshall' ryegrass grazed continuously or rotationally. Two pastures of Surrey and two pastures of Marshall that had been subdivided into six paddocks each were used in 2 yr. Yearling steers grazed the pastures. In the 1st yr, pastures within a cultivar were either continuously or rotationally grazed. Thus, animal performance on the rotationally grazed treatments was unreplicated and the data were not included in the statistical analysis. In the 2nd yr, each pasture contained both continuous and rotational groups of cattle. Cattle gains for the two cultivars were not different in either yr 1 (P > .26) or yr 2 (P > .17). In yr 2, continuous grazing allowed for greater individual animal gains (P = .03) than rotational grazing. However, the lower stocking rate of continuously grazed paddocks resulted in a decreased pasture gain (P = .001) of 301 compared with 403 kg/ha for the rotationally grazed paddocks. Forage quality was not different between Surrey and Marshall ryegrass, but there was a tendency (P = .12) for Surrey to have less forage mass during yr 1. Overall, continuously grazed paddocks had lower CP and NDF and higher in vitro true digestibility than rotationally grazed paddocks. Surrey was equivalent to Marshall ryegrass in animal performance and quality, and continuous grazing provided higher individual animal performance but lower performance on a gain per hectare basis than rotational grazing.