Característica produtiva e estrutural de pastos mistos de aveia e azevém manejados em quatro alturas sob lotação contínua

Abstract

It was monitored variables related to production and structure of oat (Avena strigosa Schreb) and ryegrass (Lolium multiflorum Lam) pastures managed at four sward heights (10, 20, 30, and 40 cm) on continuous grazing with variable stocking (put and take). It was used crossbred beef steers at approximately 10 months of age and an average initial weight 190 kg in a complete random block design with three replicates. The type of sward height distribution in six different sample dates as well as the forage dry mass prediction through sward heights were investigated. Forage mass linearly increased according to the sward height: for each 1-cm increase of the height above 10 cm, there was an approximately 107 kg DM/ha addition in the forage mass. There was no effect of sward height on the accumulation rate (55.8 kg DM/ha) neither on the dry matter total production (8,210 kg of DM/ha). Frequency distributions fitted to the normal model in only one out of the 96 analyzed data series. Gamma type distribution was the one that was the most frequently adjusted to sward height data, however, once grazing was started, pasture heterogeneity was so high that height distribution did not fit any of the investigated models. It is possible to estimate forage dry mass on the pasture by its average height so it is suggested to establish variable heights over the grazing cycle aiming to manage the heterogeneity caused by the animal. © 2010 Sociedade Brasileira de Zootecnia.