Abstract

GLIENKE, Carine Lisete et al. Grazing ecology of female lambs on Italian ryegrass plus red clover pasture under different defoliation intensities. R. Bras. Zootec. [online]. 2010, vol.39, n.1, pp. 51-60. ISSN 1806-9290.  http://dx.doi.org/10.1590/S1516-35982010000100007.

The relationship between pasture dynamics and ingestive behavior of female lambs was studied on Italian ryegrass (Lolium multiflorum Lam.) plus red clover (Trifolium pratense L.) mixture under a range of defoliation intensities. Rotational grazing was used and the grazing interval was determined by the thermal sum of 313 degree days. The initial pre-grazing canopy height disappearance values were 65 (very high), 58 (high), 47 (medium) and 37% (low). The sward vertical structure was similar among defoliation intensities. The forage allowance decreased linearly as defoliation intensities increased, with 0.35 bite/minute reduction for each 1% increase in forage allowance. The bite rate and number of bites/feeding station decreased with reduced contribution of leaves in the sward structure. It was associated, respectively, with an increase and a decrease of NDF and CP levels in forage as grazed by female lambs. The pasture cycle proves to be more important than defoliation intensities as a source for changes in feeding stations and displacement patterns of female lambs.

Keywords : bite rate; feeding stations; ingestive behavior; Lolium multiflorum; pasture structure; Trifolium pratense.