1. Effect of high and low residual herbage mass of a tropical pasture grazed by goats. 1. Grazing behaviour.
- Author
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Fernandes Jr., J. S., Resende, K. T., Fernandes, J. J. R., Tedeschi, L. O., Reis, R. A., Fernandes, M. H. M. R., and Silva, H. M.
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ROTATIONAL grazing , *GRAZING , *PASTURES , *GRASSES , *GOATS , *GUINEA grass , *BEHAVIOR - Abstract
The objective of this study was to determine the grazing behaviour of F1 Boer x Saanen goats maintained in a tropical pasture (Panicum maximum Jacq), under rotational grazing system in different sward structure. The area was divided into 12 paddocks of 990 m2 each, allocated in six blocks. Each paddock was divided into two identical plots (treatments, TRT) with high residual (HR, 3.1 t/ha of green herbage mass; GHM) and low residual (LR, 2.0 t/ha GHM). Each plot was grazed for three consecutive d (D1, D2 and D3) before animals were rotated. Grazing time (GT, min) was recorded during daytime (0700 to 1900 h) and behavior was observed every 10 min, with four animals per TRT. Bite rate (BR, bites/min) was the total number of bites during three minutes, and bite mass (BM, g/bite) was estimated with esophageally fistulated animals. Measurements were conducted during three consecutive grazing cycles of 36 d. The mean stocking rate for HR was 33 goats/ha (or 6.6 animal unity (AU)/ha) and for LR was 43 goats/ha (or 8.4 AU/ha). The GT increased from D1 to D3 (468, 491 and 535 min for D1, D2, D3) in the LR, but did not differ in the HR (468 min). BR did not differ between treatments (P=0.12) or among days (P=0.42), and averaged 80.3 bites/min. In contrast, BM was higher (P=0.01) in HR (0.18 g/bite) than in LR(0.15 g/bite), and decreased from D1 to D3 (0.22; 0.16 and 0.11 g/bite). These differences can be explained by the low herbage allowances in the LR. We observed the functional relationship between BM and GT, in which the animal increased the grazing time to offset the lower BM. Our findings are consistent with the general assumption that BM are greatest during the first day, as a result of the trade-off between quantity and quality of the herbage mass. a Sponsored by FAPESP and CNPq, Brazil. [ABSTRACT FROM AUTHOR]
- Published
- 2006