Tropical Grasslands (2006) Volume 40, 84–93

Tiller cohort development and digestibility in Tanzania guinea grass (Panicum maximum cv. Tanzania) under three levels of grazing intensity

P.M. SANTOS1, M. CORSI2, C.G.S. PEDREIRA2 AND C.G. LIMA3

1Embrapa Pecuária Sudeste, Rod. Washington Luiz, São Carlos-SP, Brazil
2Departamento de Zootecnia, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, Piracicaba-SP, Brazil
3Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga-SP, Brazil

Abstract

The aim of this work was to characterise tiller cohorts of Tanzania guinea grass (Panicum maximum cv. Tanzania) throughout a growing season to identify factors that favour low stem production in order to develop management alternatives to improve its utilisation and quality. The experiment was carried out on an irrigated pasture under rotational stocking between October 1999 and May 2000. The experiment consisted of 3 grazing treatments (high, medium and low intensities) replicated 4 times. No specific tiller cohort was responsible for most of the dry mass production, so it is not possible to base management of Tanzania guinea grass on the characteristics of a single cohort. The contribution of tiller cohorts to total forage and stem production was affected by grazing intensity with the youngest cohorts contributing most on heavily grazed areas. Leaf percentage was related to plant development stage and declined over the grazing cycles in each tiller cohort. The digestibility of tiller cohorts decreased over the grazing cycles and was higher on heavily grazed areas. Favouring higher tiller turnover through management appears to be the best way to reduce the negative effects of flowering on herbage treatment in April–May.

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