Effects of different additives and densities on silage quality of hybrid Pennisetum

In order to improve the quality of hybrid Pennisetum silage, an orthogonal design was adopted in this study, with four factors at three levels, namely corn flour (A) (0, 3%, and 6%), urea (B) (0, 0.3%, and 0.6%), lactic acid bacteria (C) (0, 5, and 10 g·t⁻¹), and density (D) (700, 800, and 900 kg·m⁻³), to explore the effects of the four factors on quality and nutritional value of Pennisetum silage and to screen the optimum silage density and additive amount of corn meal, lactic acid bacteria, and urea. The results showed that: 1) The comprehensive scores of sensory assessment in the six treatment groups ranged from 9 to 15, with a grade 2 or above. 2) Corn flour significantly increased crude protein (CP) and relative feeding value (RFV) (P < 0.01) and significantly decreased neutral detergent fiber (NDF), acid detergent fiber (ADF), crude ash (Ash), pH value, and ammonia nitrogen content in a dose-dependent manner (P < 0.01). 3) Urea dose-dependently enhanced CP and RFV values (P < 0.01) but significantly reduced NDF and ADF content (P < 0.05). When urea was added to 0.6%, CP increased by 7.05%, but NDF and ADF decreased by 1.38% and 1.45%, respectively. 4) When treated with lactic acid bacteria at 5 g·t⁻¹ and density at 700 kg·m⁻³, respectively, the silage possessed the highest RFV but the lowest values of NDF and dry matter (DM) in the treatments. In conclusion, the three additives improve the fermentation effect of hybrid Pennisetum silage in the order of flour > urea > lactic acid bacteria, with the best effect at 700 kg·m⁻³. The optimal combination includes 6% corn flour, 0.6% urea, 5 g·t⁻¹ lactic acid bacteria, and density of 700 kg·m⁻³.