African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6576

Full Length Research Paper

Effect of cutting time on agronomic and nutritional characteristics of nine commercial cultivars of Brachiaria grass compared with Napier grass during establishment under semi-arid conditions in Rwanda

Mupenzi Mutimura
  • Mupenzi Mutimura
  • Department of Animal Production, Kigal Rwanda Agriculture Board (RAB), P. O. Box 5016 Rwanda.
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Cyprian Ebong
  • Cyprian Ebong
  • Department of Animal Production, Kigal Rwanda Agriculture Board (RAB), P. O. Box 5016 Rwanda.
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Idupulapati M. Rao
  • Idupulapati M. Rao
  • International Center for Tropical Agriculture (CIAT), A. A. 6713, Cali, Colombia.
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Ignatius V. Nsahlai
  • Ignatius V. Nsahlai
  • Department of Animal Science and Poultry Science, Earth and Environmental Sciences, University of KwaZulu-Natal, School of Agricultural, Pietermaritzburg Campus, Private Bag X01, Scottsville, 3209, South Africa.
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  •  Received: 23 May 2017
  •  Accepted: 19 July 2017
  •  Published: 31 August 2017

Abstract

A study was conducted to identify the most productive cultivars and their cutting management to optimize nutrient productivity in semi-arid areas of Rwanda. Four cultivars of Brachiaria brizantha (Piatá, MG4, Marandú and Xaraes), two cultivars of Brachiaria humidicola (Llanero and Humidicola), two cultivars of Brachiaria hybrid (Mulato and Mulato II) and one cultivar of Brachiaria decumbens (Basilisk) were evaluated against Napier grass (Pennisetum purpureum) in an on-farm trial in a complete randomised block design with four replicates. Forage samples were collected at 60, 90 and 120 days after planting (DAP) and analysed for dry matter (DM), crude protein (CP), organic matter (OM) and neutral detergent fibre (NDF). The nutritional values were also estimated using in vitro gas production (IVGP) and its kinetic parameters, in vitro apparent degradable dry matter (ivADDM), digestible organic matter (DOM), metabolisable energy (ME), partitioning factor (PF) and degradable efficiency factor (DEF). For all cultivars and species, the DM, CP, OM, ivADDM and DOM increased from 60 to 90 DAP and declined thereafter. The NDF contents increased with increase in plant age. Grasses cut at 90 DAP had the highest gas production. The ME differed among grasses and DAP where Piatá had the highest. Furthermore, degradability parameters (A, B, C) and half time (T1/2) differed among grasses and between cutting times. The PF and DEF were correlated with ME. The most promising cultivars were Basilisk, Marandú, Piatá and Mulato II because of their high in these nutritional characteristics.

 

Key words: Chemical composition, metabolisable energy, degradability parameters, degradation efficiency factor.