Proximate analysis and aerobic stability of forage mixtures composed of Cenchrus purpureus cv. Taiwan A-146 and Paspalum virgatum L. ensiled under laboratory conditions

To evaluate the quality of silage composed of Cenchrus purpureus cv. Taiwan A-146 and Paspalum virgatum L. under laboratory conditions, both forage species were harvested south of Lake Maracaibo-Venezuela. The plant material was reduced to 2.5 cm and distributed according to the treatments (T): T0: 100% C. purpureus (CPT); T1: 100% P. virgatum (PV); T2: 50% CPT + 50% PV; T3: 75% CPT + 25% PV and T4: 25% CPT + 75% PV; then, polyethylene bags were used to fill the silo, in which each mixture was placed, incorporating molasses at 6% of its weight as an additive; then, oxygen was extracted to seal the bags and they were kept in darkness for 30 days. All mixtures were subjected to proximate analysis before and after storage. A completely randomized design was chosen, using Tukey's test for multiple comparisons of means. Statistical analysis revealed that CPT and fresh PV were different (p<0.05) for the variables moisture, dry matter, crude protein and ash, but similar (p>0.05) in ethereal extract, crude fiber, neutral detergent fiber, acid detergent fiber and nitrogen free extract. After fermentation, crude protein (CP) content increased (p<0.05) in CPT, while the other parameters increased without changes (p>0.05), except for nitrogen free extract, which reduced its post-silage concentration, although energy increased (p>0.05), since the calculated theoretical value (kcal/g) was higher in the silage but similar (p>0.05) with respect to the initial fresh forage; Aerobic stability was influenced by the proportion of CPT, because the high moisture content reduced its suitability time to be consumed. It is concluded that, theoretically, under laboratory analysis conditions, the forage species evaluated represent a feasible alternative for supplementing large ruminants, since they are medium quality pastures with a better nutritional profile when ensiled.