Revista Brasileira de Zootecnia
versão On-line ISSN 1806-9290
DIFANTE, Gelson dos Santos et al. Sward structure and nutritive value of tanzania guineagrass subjected to rotational stocking managements. R. Bras. Zootec. [online]. 2009, vol.38, n.1, pp.9-19. ISSN 1806-9290. http://dx.doi.org/10.1590/S1516-35982009000100002.
The objective of this work was to evaluate the sward structure and nutritive value of Panicum maximum Jacq. cv. Tanzânia subjected to rotational stocking managements characterised by a common pre-grazing condition of 95% canopy light interception (LI) and two post-grazing residues, 25 and 50 cm. Treatments (95/25, 95/50 - LI/residue) were assigned to experimental units (groups of six 2500 m2 paddocks per treatment) according to a complete randomised block design, with two replications. The variables measured corresponded to: canopy light interception, pre and post-grazing sward height, herbage mass and pre and post-grazing morphological composition, herbage bulk density, herbage accumulation and nutritive value (including to IVOMD) of the morphological components. Pre-grazing herbage mass did not differ between residues, although the herbage accumulation rate was higher for the 50 than the 25 cm (164.9 and 90.6 kg/ha.day DM, respectively). Post-grazing herbage mass values were higher for the 50 cm residue and were characterised by a higher proportion of leaf blade in relation to the 25 cm treatment, which presented a higher proportion of dead material. On average, the contents of crude protein (CP), neutral detergent fibre (NDF) and lignin in acid detergent (LAD) as well as the values of the "in vitro" organic matter digestibility (IVOMD) were similar for both treatments. Crude protein and IVOMD decreased and NDF and LAD increased from top to the bottom of the sward, indicating grazing intensity as an important variable for promoting adjustments in the grazing efficiency and nutritive value of the consumed herbage by the grazing animals.
Palavras-chave : grazing management; herbage accumulation; Panicum maximum; post-grazing height.