Losses through gases and effluent and nutritional value of Brachiaria decumbens with addition of soybean hulls

The objective of this experiment was to evaluate the losses of nutrient through gases and effluents, the nutrient recovery, fermentation parameters and the chemical parameters of silages of Brachiaria decumbens with the addition of soybean hulls, testing five levels of inclusion: 0, 10, 20, 30 and 40% (as is), with five replications per treatment. After the standardization cut of the forage, performed at 5 cm from the soil level, the soil was fertilized with nitrogen and potassium in the form of ammonium sulfate and potassium chloride, respectively, at 60 kg/ha. After 60 days, the grass was cut at 10 cm from the soil and ensiled. Experimental silos with capacity of 10 liters with Bunsen valve were used. Silos had 3 kg of sand conditioned at the bottom for retention of the effluents. The results show that the contents of dry matter, crude protein, acid detergent insoluble fiber and total digestible nutrients presented positive linear behavior with the inclusion of soybean hulls. In the grass silages with addition of soybean hulls, there was greater recovery of dry matter in relation to the control silage, which is a reflection of the negative linear behavior for the values of losses of gases and effluent. There was quadratic behavior in the pH values and negative linear behavior for the ammonia N values and buffering capacity with the inclusion of the additive in the grass silage. Inclusion of soybean hulls is sufficient to improve the fermentation pattern and minimize the losses through gases and effluents, contributing to the nutrient recovery, in addition to promoting overall improvement of the nutritional value of Brachiaria grass silages.

本试验旨在评估添加大豆皮的俯仰臂形草（Brachiaria decumbens）青贮饲料的气体与流出物养分损失、养分回收率、发酵参数及化学参数，设置5个添加水平（以鲜重计：0、10、20、30、40%），每个处理设5次重复。先对牧草进行标准化刈割，刈割高度距地面5 cm，随后以硫酸铵和氯化钾分别作为氮源和钾源，按60 kg/ha的用量对土壤施肥。60天后，将牧草距地面10 cm处刈割并制作青贮。试验采用带本生阀（Bunsen valve）的10升容量青贮罐，罐底铺设3 kg沙子以留存流出物。结果表明，随着大豆皮添加量的提升，干物质、粗蛋白质、酸性洗涤不溶性纤维及总可消化养分含量均呈正向线性变化趋势。与对照组青贮饲料相比，添加大豆皮的俯仰臂形草青贮饲料的干物质回收率更高，这与气体和流出物损失量呈负向线性变化的结果相契合。在添加该添加剂的草青贮饲料中，pH值呈二次变化趋势，氨态氮含量及缓冲能力呈负向线性变化趋势。添加大豆皮可有效改善发酵模式，降低气体与流出物造成的养分损失，提升养分回收率，同时全面提升俯仰臂形草青贮饲料的营养价值。