Abstract

The grassland resource could be better managed if the effect of different defoliation regimes on the amount of the dry matter and nutritive value was known.  Consequently, 9 ecotypes of Panicum maximum were evaluated in central region of Benin with an average 1100 mm annual rainfall during 3 years for ley pasture without any fertiliser input. Three cutting regimes (3-10-3, 5-6-5 and 6-4-6-week) were tested for dry matter production (DM), crude protein (CP) content, CP production and mineral (Ca, Mg, P, K, Na, Zn, Mn, Cu and Co) contents. Significant differences were observed between ecotypes (p<0.001), cutting regimes (p<0.001) and years (p<0.001) for DM and CP production. Ecotype and cutting regime influenced significantly CP content (p<0.05) but year had no influence. Forage harvested from 3-10-3-week regime produced significantly (p<0.05) more DM (4742 kg DMha^-1) than 5-6-5-week (3635 kg DMha^-1) or 6-4-6-week cutting regime (3789 kg DMha^-1).  But the reverse effect was observed for CP content as 3-10-3-week regime (5.68 gkg^-1 DM) had significantly (p<0.05) lower CP than those of 5-6-5-week (8.55 gkg^-1 DM) or 6-4-6-week cutting regimes (7.15 gkg^-1 DM). Mineral concentrations varied between ecotypes but not by cutting regimes and years. Three ecotypes (n° 1, 4 and 5) consistently outproduced than others and can be harvested through 5-6-5-week cutting regime. P, Na, Zn and Cu deficiencies were the most common detected in the cropped forages. 

Key words:  Guinea grass, ecotypes, yield, crude protein, mineral contents, Benin.