This study evaluated the effect of harvest age and fertilisation rate on nutrient production of Red Napier Grass (Pennisetum purpureum cv. Red) (RNG) in the fifth harvest period. The design used was a factorial completely randomised design (CRD), with two factors, namely harvest age (50, 60, 70, and 80 days) and fertilization level (P0: 0 kg N/ha/year, P1: 150 kg N/ha/year, and P2: 300 kg N/ha/year). Each treatment combination was repeated three times, resulting in 12 treatments. Parameters observed included nutrient content i.e. Dry Matter (DM), Organic Matter (OM), Crude Protein (CP), Crude Fiber (CF), Crude Fat and nutrient production of DM, OM and CP. The results showed that harvesting age and fertilization rate had a significant effect on nutrient content. The interaction between harvest age and fertilizer level also had a very significant effect on nutrient content. The results also showed that harvest age and fertilizer level had a significant effect (P0.05). The highest DM and OM production was found in the P2 treatment at the age of 80 days, while CP production reached its peak at the age of 60 days with the same fertilizer level. It is recommended to harvest Red Napier Grass at the age of 80 days with fertilizer treatment P2 (300 kg N/ha/year) to get optimal yields. In addition, the CP content that decreases at older harvest ages can be added with concentrate feed in animal.
Aprilia et al. (Tue,) studied this question.