| Abstract: | Evaluations of two hybrid bermudagrass [Cynodon dactylon (L.) Pers.] cultivars were performed to evaluate changes in sward herbage mass (HM), composition (leaf mass, leaf distribution) and quality (IVDMD) under continuous and rotational grazing. Multiple stocking rates (SR) of 6.7, 8.0, 9.5, and 12.4 hd ha^-1 were used for this study. Rotationally grazed pastures were subdivided into four paddocks of equal size and animals were rotated to a new paddock every 7 days. All paddocks were shredded after the animals were rotated. Estimates of herbage mass were obtained through the use of destructive and nondestructive techniques. Destructive techniques included the harvest of 900 mm^2 quadrats (QD) while non-destructive techniques included estimates of pasture height (HI) and visual scores (VS). When averaged across cultivars, stocking rates, and grazing methods, HM declined from May to August and showed a slight increase during September. Herbage mass and from May to August and showed a slight increase during September. Herbage mass and HM per animal declined with increasing SR for continuously grazed pastures. In contrast, HM did not decline as SR increased under rotational grazing, while HM per animal did decline as SR increased. Across cultivars, HM per animal was significantly less under rotational grazing (71.5 kg hd^-1) than under continuous grazing (389 kg hd^-1). Across cultivars, SR, and grazing methods mean diet composition consisted of 87 percent leaf. For both Brazos and Coastal bermudagrass, animal diets contained a higher percentage leaf than was observed in the top strata of the canopy. Mean average daily gain (ADG) was greater on continuous than rotationally grazed pastures (0.57 versus 0.50 kg hd^-1 d^-1). A lower total leaf mass (TLM) can be attributed primarily to the poor performance of animals grazing the heavily stocked (12.4 hd ha^-1) rotational pastures. Even though HM was consistently less on rotational pastures than continuously grazed pastures, the rotational pastures exhibited a higher mean in vitro dry matter digestibility (TVDMD). Mean ADG was similar between rotational and continuously grazed paddocks except where TLM per animal declined below 74 kg hd^-1. It is suggested that HT may be an effective management tool for adjusting SR on bermudagrass pastures. |
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