The aim of this study was to evaluate the structural characteristics and herbage accumulation of tanzania guineagrass (Panicum maximum cv. Tanzania) under rotational grazing and subjected to combinations of two grazing frequencies (time for the canopy to intercept 90 or 95% of the incident light) and two post-grazing heights (30 or 50 cm). Treatments were assigned to experimental units according to a 2 × 2 factorial arrangement in a completely randomized design, with three replications. Sward heights at pre-grazing were consistent during the experimental period and were of around 65 and 75 cm, for 90% and 95% of light interception (LI), respectively. Pastures managed with post-grazing height of 50 cm and 90% of LI had higher number of grazing cycles when compared with those submitted to post-grazing height of 30 cm and 95% of LI. Herbage mass production was higher in summer, intermediate in late spring and lowest in fall and winter and early spring. Herbage mass and lamina leaves production were higher in pastures managed with post-grazing height of 30 cm when compared with post-grazing height of 50 cm. Nevertheless, the effects of frequency on herbage mass production were associated with the post-grazing height used. The LI levels (90 or 95%) did not affect leaf lamina production. The combinations of frequency and severity of grazing resulted in little variation in the morphological composition of forage, except in the autumn, when there was a higher percentage of dead material in pastures managed with post-grazing height of 50 cm when compared with those with post-grazing height of 30 cm. The rotational grazing of tanzania guineagrass should be initiated when canopy intercepts 95% of incident light until a post-grazing height of 30 cm. When necessary and in order to generate flexibility in grazing management, the tanzania guineagrass can be grazed with 90% of light interception.
forage production; grazing management; light interception; sward height
