Effect of six-weekly harvests on the yield, chemical composition and dry matter degradability of Panicum maximum and Stylosanthes hamata in Nigeria

Abstract

The dry matter (DM) yield and degradability of 6-week-old harvests of tropical forages were measured over a season. The forages were nitrogen-fertilized Guinea grass (Panicum maximum, NFG), unfertilized Guinea grass (UFG), Verano stylo (Stylosanthes hamata,VS), a Guinea grassVerano stylo mixture (GSM) and Guinea grass in the grassVerano stylo mixture (GGSM). Six-week-old forages were made possible through a cutting regime, which produced four harvests in the growing season. The DM yields of the forages differed significantly (P < 0·001) and showed a significant reduction (P < 0·01) across the season. Crude protein and neutral-detergent fibre concentrations were significantly (P < 0·01) different between the forages but there was no difference between harvests. The DM degradability of the forages at all harvests were significantly (P < 0·001) different with differences in the soluble fraction (a), degradable fraction (b), potential degradability (PD) and effective degradability (ED), but rate of degradability (c) did not show any significant difference between the forages. Significant (P < 0·01) differences were found between harvests for b and PD, and for the interaction between forage and harvest for b, PD and ED but were not found for the a and c fractions. Both the PD and ED values of all the forages fell with advancing harvests. Although the 6-week-old harvests of forage were found not to influence the characteristic reduction in yield of tropical grasses over time, it is concluded that such a management system could be used to obtain forage of relatively high nutritive value during the growing season