Conservation and chemical composition of Leucaena Leucocephala plus fresh or wilted Pennisetum purpureum mixed silages

Objective. Quantify the effects of mixing Leucaena (L) with King grass forage, fresh (K) or wilted (Kp), on the fermentation process and chemical composition of mixed silages. Materials and methods. Silos were produced mixing several proportions (kg:kg) K:L and Kp:L (100:0; 75:25; 60:40; 50:50; 40:60 and 0:100) of both types of plants, under a completely randomized design of four replications. The quantity of organic acids (butyric, acetic, lactic), pH, ammonia nitrogen percent and some of the typical bromatologic nutrients of the forage before and after ensiling were measured. The treatment effects were evaluated through variance and regression analysis. Results. The results clearly proved the differences (p<0.05) between King grass and Leucaena which promote its mixing and wilting: better legume contents of crude protein (24 vs. 7%), dry matter (33.77 vs. 22.05%) and crude fiber (26.53 vs. 32.5%). Clear benefits on the conservation process of mixed silages were also measured: higher lactic productions and less butyric, acceptable pH (4.02-4.8) and protein degradation (<8%). In addition, a positive effect on the chemical composition of the aforementioned silages was quantified (crude protein, dry matter and crude fiber progressive improvement). Conclusions. Mixed K+L silages are better than pure K if L is included below 25% in KL and up to 40% when K has been wilted. Higher inclusions of L will worsen the conservation process and will limit its elaboration.