Growth and forage quality of Napier grass as ruminant feed, influenced by poultry litter application rate and harvest age

Abstract

This study evaluated the effects of poultry litter application rates (0, 5, 10, and 15 tons/ha) and harvest ages (45, 60, 75, and 90 days after cutback, DAC) on the growth parameters, biomass yield, proximate composition, and cell wall fiber fractions of Napier grass. A 4 × 4 factorial experiment was arranged in a split-plot design with three replications at the Livestock Teaching and Research Farm, Federal University Wukari. Poultry litter application rate significantly (p < 0.05) influenced plant height, leaf width, number of tillers, leaf: stem ratio, leaf area index (LAI), and biomass yield, with the highest biomass yield (41.04 tons/ha) recorded at 10 tons/ha. Harvest age significantly affected all measured parameters except leaf: stem ratio and stand circumference. Biomass yield peaked at 75 DAC (38.86 tons/ha), while crude protein (CP) content was highest at 60 DAC (7.85%) and lowest at 75 DAC (4.97%). Fiber fractions increased with maturity. Significant interactions (p < 0.05) between poultry litter and harvest age were observed for most growth and quality parameters. The combination of 15 t/ha poultry litter harvested at 45 DAC produced the highest CP (9.65%), while 10 tons/ha harvested at 75 DAC gave the highest biomass (48.76 tons/ha). Crude protein values across all treatments fell below the 8–12% requirement for goat production, indicating the necessity for protein supplementation. For an optimal balance of biomass yield and forage quality in smallholder goat production systems in Taraba State, poultry litter application at 10 t/ha combined with harvest at 60–75 DAC is recommended