R. Bras. Zootec.01/Sep/2009;38(9):1685-94.
Structural characterization of a natural pasture vegetation from Pampa Biome under different herbage allowance management strategies
DOI: 10.1590/S1516-35982009000900007
The objective of this trial was to investigate the spatio-temporal dynamics of feeding sites stratified by strips of herbage mass and sward height, and the percentage of effectively grazed area, herbage growth rate and dry matter yield of a natural pasture from Pampa Biome managed with different herbage allowance management strategies. A randomized block design with two replications was used with three fixed herbage allowance (8, 12 and 16%) and three herbage allowance variables throughout the year (8-12%, 12-8%, and 16-12%), with first value corresponding to the spring season. The 8% fixed herbage allowance presented greater effectively grazed area, but the average height and herbage mass were lower than in other allowances. The highest herbage allowance, 16% and 16-12%, presented 9.0 cm average sward height and herbage mass of 2,000 kg/ha dry matter, and a smaller effectively grazed area than the 8% and 8-12% herbage allowances. In spite of the different management strategies used, between 60 and 70% of feeding sites occurred in strips considered to constrain animal intake, except in the 16% and 16-12% treatments, in which a smaller frequency of feeding sites in strips lower than 6.0 cm was registered. In general, the feeding sites were concentrated on strips <6 cm SH, and herbage masses <1000 and 1000-1500 kg/ha dry matter, in all allowances. However, at 16-12% and 8-12% herbage allowances, the feeding sites were better distributed among the strips for herbage mass and sward height.
Keywords: feeding sites; grazing intensity; herbage mass; sward height; sward structure