Effect of poultry litter application rate and maturity on growth components and nutritional value of Super Napier grass as ruminant feed

Abstract

The study was conducted at the Livestock Teaching and Research Farm of the Federal University Wukari, Taraba State, Nigeria, to evaluate the effect of poultry litter application rate and harvesting age on growth components, herbage yield and nutritional value of Super-Napier grass (Pennisetum purpureum × Pennisetum americanum). The experiment was a 4 × 4 factorial arranged in a Randomised Complete Block Design (RCBD) with three replicates. Four levels of poultry litter (0, 5, 10, and 15 t/ha) and four harvesting ages (45, 60, 75, and 90 days after cutback) were evaluated. Results showed that increasing poultry litter application rate significantly (P<0.05) improved plant height, stand circumference, number of tillers, stem girth, leaf area index, and biomass yield. Plots that received 15 t/ha recorded the highest plant height (272.81 cm) and biomass yield (71.70 t/ha), while the control recorded the lowest (232.53 cm and 29.57 t/ha, respectively). Harvesting at 90 days after cutback produced the tallest plants (297.42 cm) and the highest biomass (60.14 t/ha), but with the lowest crude protein content (6.27% DM) and the highest Lignin fraction (19.71%). The 60-day harvest yielded the highest crude protein (7.32% DM). A significant (P<0.05) interaction effect was observed between application rate and harvesting age for most growth and nutritional parameters. It was concluded that poultry litter at 10 t/ha combined with harvesting at 60 days after cutback optimizes both yield and nutritional quality of Super Napier grass for ruminant feeding in the Nigerian Guinea Savanna zone.