EFFECTS OF `HARVESTING AGE AND INTENSITY ON BIOMASS YIELD, CHEMICAL COMPOSITION AND IN VITRO DIGESTIBILITY OF BRACHIARIA GRASS IN NORTHERN GHANA

Abstract

The study was conducted to investigate the effect of harvesting age and intensity on biomass yield and the effect of harvesting age and botanical fraction on chemical composition and in vitro dry matter true digestibility (IVDMTD) of Brachiaria mulato II grass. Experimental design for the chemical analysis was 2 ×2 factorial. The experimental design for the in vitro Digestibility analysis was 2 ×2 factorial. The agronomic data was analyzed with ANOVA in a 2×2 factorial using GenStat. The chemical composition and fiber digestibility data were analyzed with ANOVA in 2×2 factorial using GenStat. The interactive effect of harvesting age and intensity was significant for tiller number only at location one. Grasses harvested 100 days after planting produced the highest average tiller numbers of (107.1 cm) and (98.9cm) for location one and two respectively. Grasses harvested 80 days after planting produced the highest average plant height of (47.57cm) and (47.45cm) for location one and two respectively. The interactive effect of harvesting age and intensity was not significant for both initial and regrowth harvest for both locations. Grasses harvested at 100 days after planting produced the highest average initial biomass yield of (1532kgDM/ha) and (2536.5kgDM/ha) for location one and two respectively whiles that of the regrowth is (856.5kgDM/ha) and (918.5kgDM/ha) for location one and two respectively. For the chemical analysis of Brachiaria mulato II, the interactive effect of harvesting age and botanical fraction was significant on Ash, OM, NDF and ADF at the initial harvest for location one. On the other hand, the interactive effect of harvesting age and botanical fraction was significant on CP and ADF in the regrowth for location one. Botanical faction affected all the parameters except HM whiles harvesting age was significant on Ash, OM, CP and NDF in the regrowth for location one. The interactive effect of harvesting age and botanical fraction was significant on ADF and HM at the initial harvest for location two. On the other hand, the interactive effect of harvesting age and botanical fraction was significant on Ash, OM and ADF in the regrowth for location two. Botanical faction affected all the parameters whiles harvesting age was significant on CP, NDF and HM in the regrowth for location two. The interactive effect of harvesting age and botanical fraction was significant for all in vitro digestibility parameters except dNDF in the initial harvest in location one. Also, the interactive effect of harvesting age and botanical fraction was significant for only NDFD in the regrowth harvest for location one. However, the botanical fraction’s main effect was only significant on NDFD and dNDF in the regrowth in location one. The botanical fraction’s main effect was significant on all parameters except NDFD in the initial harvest in location two. However, botanical fraction and harvesting age main effect was significant on all parameters except NDFD in the regrowth in location two. In conclusion, harvesting age and intensity has an effect on biomass yield, plant height and tiller number. Beside these, harvesting age and botanical fraction has an effect on chemical composition and in vitro dry matter true digestibility (IVDMTD) of Brachiaria mulato II grass in this research.