Evaluation of three species of Brachiaria spp with rotational grazing methods for bovine fattening

Abstract

This work was aimed at evaluating beef cattle performance regarding rotational grazing on Brachiaria humidicola, B. brizantha cv. Marandu and B. decumbens tropical forage grasses. The experiment was carried out on the Água Claras Farm in the piedmont municipality of Tame in Colombia’s Arauca department; the area is 430 masl, has 8°C average temperature, 2,890 mm/year annual rainfall, 1,800 light hours/year monomodal distribution and 83% relative humidity. Seventy-five 22±2 month-old beef cattle, weighing 300±40 kg were used in this study; a completely randomised design was used involving three treatments (grazing methods) and 25 repetitions per treatment (i.e. giving 75 experimental units.) The experimental grazing methods involved cattle grazing on in forty-four 0.5 ha pastures, cattle grazing on B. brizantha cv. marandú on fiftee1.4 ha pastures and cattle grazing on B. decumbens in 1, 2 and 2.5 ha pastures. The pastures enabled cattle to have access to water at will and a mineralised salt supply was provided; the cattle were weighed while fasting at the beginning and the end of the trial. Forage availability, the amount of forage dry matter (FDM), crude protein (CP), neutral detergent fibre (NDF), acid-detergent fibre (ADF), urease activity (UA) and calcium, phosphorus and magnesium concentration/intake were the variables studied. The cattle had a 60-day adaptation period, followed by the 80-day experimental phase. The results revealedeefregarding daily weight gain. The grazing methods did influence (p<0.05) CP, NDF, ADF, calcium, phosphorus and magnesium content, as well as UA. Grazing on Brachiaria spp. thus does not affect fattening cattle’s performance.