Effect of grazing frequency and intensity on Lolium perenne L. pastures under subtropical conditions: herbage quality

The cellulase dry matter disappearance (CDMD) and herbage nitrogen (N) of Lolium perenne (perennial ryegrass) were evaluated for pastures grown under subtropical conditions for two years, under five combinations of grazing frequency and intensity, each applied in a rotational grazing system. These quality factors were also evaluated for a simulated continuous grazing (CG) system. Low frequency, low intensity grazing produced lower CDMD and herbage N levels than higher grazing frequencies and intensities. These differences were, however, generally small. Overall, levels of herbage digestibility (estimated by CDMD) and N fell within similar ranges to those observed for perennial ryegrass in temperate environments. Seasonal trends in quality were characterized by high levels, during late autumn to early summer (May to October) and low levels during mid-summer to early autumn (January to April). These data would tend to support high frequency grazing as part of the management programme for perennial ryegrass. It is cautioned, however, that for subtropical conditions in South Africa, adopting frequent grazing may reduce persistence of perennial ryegrass.Keywords: cellulase; cellulase dry matter disappearance; continuous grazing; digestibility; dry matter; grazing frequency; herbage; herbage nitrogen; lolium perenne; nitrogen; pastures; perennial ryegrass; pietermaritzburg; rotational grazing; ryegrass; seasonal trends; south africa; ukulinga research stationAfrican Journal of Range & Forage Science, 13(1