Animal performance and sward characteristics of Mombaca guineagrass pastures subjected to two grazing frequencies

The aim of this work was to compare grazing management practices of Mombaca guineagrass (Megathyrsus maximus syn. Panicum maximum cv. Mombaca) based on the sward incident light interception (LI) concept. We tested, when the regrowth period in rotationally stocked Mombaca guineagrass ended, if LI (90 or 95%) affected forage accumulation, sward characteristics and animal performance. Both treatments had a common post-grazing canopy height of 50 cm and were replicated 4 times in a randomized complete block design. Pastures were sampled pre- and post-grazing to determine forage mass, morphological composition and forage accumulation rate (FAR). Nutritive value (NV) was estimated in pre-grazing samples. Stocking rate was adjusted twice a week, and animals were weighed every 28 days. Pre-grazing conditions of 90 and 95% LI were reached at pasture heights of approximately 80 and 90 cm, respectively. FAR, sward structure and NV were similar for pastures grazed at 90 and 95% LI. Consequently, stocking rate, average daily gain and liveweight gain/ha were similar for both LI treatments. Data suggest that Mombaca guineagrass can be grazed at pre-grazing heights of 80-90 cm (90-95% LI) without compromising pasture structure and animal performance provided moderate defoliation severity is employed. Further testing of this grazing strategy over longer periods should be carried out with this species as well as other tropical grasses.