Effect of spacing and age at harvest on the nutritive composition and mineral dynamics of Megathyrsus maximus cv. Mombasa

Abstract

Tropical forage systems in sub-Saharan Africa often suffer from low nutritional quality and mineral imbalance, reducing livestock productivity. This study evaluated the effect of spacing and harvest age on the nutritive composition and mineral dynamics of Megathyrsus maximus cv. Mombasa. The study investigated a two spacing (1 m × 1 m and 0.5 m × 1 m) and two age at harvest (3 and 6 weeks after regrowth) in a 2 × 2 factorial study using a split-plot design. The findings indicated that the effects of spacing × age on crude protein (CP), ash, and total carbohydrate (TC) were significant (p < 0.05). While the fiber fractions—neutral detergent fiber (NDF: 697.20 g/kg DM) and acid detergent fiber (ADF: 426.66 g/kg DM)—increased with maturity, the highest CP (166.10 g/kg DM) and Ca (4.69 g/kg DM) were measured at 1 m × 1 m spacing and 3 weeks. Potassium increased from 18.58 to 19.61 g/kg DM, while P (2.65 to 2.03 g/kg DM), Mg (3.41 to 2.93 g/kg DM), Cu (6.35 to 5.77 mg/kg DM), and Zn (25.19 to 16.50 mg/kg DM) decreased with age. The iron concentration increased from 109.60 to 257.76 mg/kg DM, resulting in high Fe:Mn and Fe:Zn ratios. Early harvest (3 weeks) and wider spacing (1 m x 1 m) resulted in high-quality forage.