R. Bras. Zootec.01/Oct/2007;36(5):1406-12.
Nutritional evaluation of elephantgrass and mombaçagrass pastures under rotational stocking as a function of different grazing periods
DOI: 10.1590/S1516-35982007000600025
Qualitative assessment of elephantgrass (Pennisetum purpureum, Schum. cv. Napier) and mombaçagrass (Panicum maximum, cv. Mombaça) pastures under rotational stocking was performed using the esophageal extrusa technique. Samples of esophageal extrusa were taken at the third, second and first days of the grazing period. The following analyses were determined: DM, CP, EE, OM, lignin (LIG), NDF, ADF, in vitro dry matter digestibility (IVDMD), lag time and degradation rate of carbohydrates, and fractions of the carbohydrates and nitrogenous compounds. The average composition of extrusa samples as a function of the days under grazing were compared through orthogonal contrasts, with subsequent adjustment of regression equations. For IVDMD and LIG, differences were observed just for the mombaçagrass. For this species, an increase of 2.57 percentual points in the indigestible fraction (fraction C) and a reduction of 3.23 percentual points in the potential degradable fraction (B2) of carbohydrates were observed. For the kinetics of degradation, it was found difference just for the mombaçagrass, showing linear reduction in the rate of degradation of the fibrous carbohydrates. Both the acid detergent insoluble protein fraction and the protein degradable fraction of elephantgrass and mombaçagrass showed linear decrease with increasing grazing period.
Keywords: esophageal extrusa; rotational stocking; tropical forage