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Rest period, canopy structural traits and steer body weight gain on intermittently grazed mombaçagrass pasture

It was evaluated the effect of two rest periods (RPs) on the canopy structural characteristics of paddocks of Mombaçagrass, a cultivar of Panicum maximum, under intermittent grazing; animal production was also evaluated. The RPs were defined by the time required for the expansion of 2.5 and 3.5 new leaves per tiller. Canopy traits response variables were: height, total green forage mass (TGFM), green leaf mass (GLM), culm mass (CM), leaf/stem ratio (L/S), and leaf area index (LAI). It was also assessed the effect of the grazing cycles (1rst, 2nd and 3rd cycles) and grazing time (first and last grazing days) on these same variables as well as on forage allowance (FA). The experimental area was divided into six and seven paddocks for the experimental treatments of 2.5 and 3.5 new leaves per tiller, respectively. The experimental design was a completely randomized with two replications. The assessed structural traits were not affected by rest period, except the leaf/stem ratio. The L/S ratio was wider in the paddocks under the shorter RP but only on the first day of the grazing period and declined with the succession of the grazing cycles. The assessed structural traits figures increased as the grazing cycles succeeded each other except the CM. Reflecting the selective grazing, all structural traits figures declined over the grazing period except the CM. The FA decreased over the grazing period reaching the value of 10.6% live weight on the last grazing day. Live weight gain averaged 824 and 760g/day/steer and animal productivities averaged 473 and 371 kg/ha, for the 2.5 and 3.5 new leaves/tiller rest period treatments, respectively, with average stocking rate of 3.6 steers/ha.

culm mass; forage mass; height; leaf


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