This study tested the hypothesis that variation of herbage allowance during the growing season influences pasture dynamics and grazing behaviour. Treatments consisted of four fixed herbage allowances during the entire year (4.0, 8.0, 12.0, and 16.0%, expressed as kg DM/100 kg live weight/day) and three variable herbage allowances (8% in spring and 12% along the rest of the grazing season; 12% spring and 8% along the rest of the grazing season; 16% in spring and 12% along the rest of the grazing season). A randomized complete block design was used, with two replicates. It was used a variable continuous stocking method, using the "put-and-take" technique. Primary and secondary productions were measured, as well as steer grazing behaviour. Results showed that low herbage allowance, as in 4% treatment, jeopardize animal performance. Herbage allowance of 8% in spring and 12% along the rest of the grazing season promoted good animal performance, suggesting this management could be interesting when manipulating sward structure. Concerning grazing behaviour, results indicated that differently from what occurs in cultivated pastures, herbage allowance or herbage mass did not explain sufficiently the grazing time observed. It was concluded that in heterogeneous vegetation, it must be considered the structural diversity on pasture characterization in order to link that with grazing behaviour.
grazing behaviour; herbage allowance; native pasture
