Effect of row spacing and maturity at harvest on the fermentative profile, aerobic stability, and nutritional characteristics of biomass sorghum (BRS 716) silage in the semiarid region of Brazil

ABSTRACT The objective was to evaluate the effects of maturity at harvest and row spacing on fermentative profile, aerobic stability, and nutritional value of biomass sorghum (BRS 716) silage. The experiment was conducted using a split-plot completely randomized block design with three row spacings (45, 70, and 90 cm) and four maturities at harvest (70, 100, 130, and 160 days) and eight replications. Polyvinyl chloride silos of known weight measuring 50 cm length and 10 cm diameter were used for silage production. Dry matter and total carbohydrate contents of the silage increased linearly, whereas crude protein and ash decreased linearly with maturity at harvest. Row spacing did not influence pH, ammoniacal nitrogen (N-NH3), gas and effluent losses, and dry matter recovery of silage. The concentrations of malic, succinic, and acetic acids and ethanol responded quadratically to maturity at harvest. The levels of neutral detergent fiber, lignin, and indigestible neutral detergent fiber increased linearly with maturity at harvest. Ruminal degradation kinetics of dry matter of biomass sorghum silage was not influenced by row spacing. BRS 716 biomass sorghum should be planted at 70-cm row spacing and harvested at 160 days for silage production based on fermentative profile, dry matter losses, and nutritional characteristics.

摘要
本试验旨在评估收获生育期与行距对BRS 716生物质高粱（biomass sorghum）青贮料的发酵特性、有氧稳定性及营养价值的影响。试验采用裂区完全随机区组设计，设置3个行距水平（45、70、90 cm）与4个收获生育期（70、100、130、160天），共8次重复。青贮制作采用已知重量的聚氯乙烯（Polyvinyl chloride，简称PVC）青贮罐，其规格为长50 cm、直径10 cm。
结果显示，青贮料的干物质与总碳水化合物含量随收获生育期线性升高，而粗蛋白与粗灰分含量则随其线性降低。行距对青贮料的pH值、氨态氮（N-NH3）、气体与流出液损失率以及干物质回收率均无显著影响。苹果酸、琥珀酸、乙酸浓度及乙醇含量随收获生育期呈二次曲线变化。中性洗涤纤维、木质素与不可消化中性洗涤纤维含量随收获生育期线性升高。生物质高粱青贮料的干物质瘤胃降解动力学不受行距影响。
综合发酵特性、干物质损失率与营养特性，用于青贮生产的BRS 716生物质高粱宜采用70 cm行距种植，并于160天收获。