NUTRITIVE VALUE OF SILAGE OF PIATÃ GRASS MONOCROP AND INTERCROPING WITH SORGHUM FOR FORAGE AND GRAZING

Abstract The objective of this study was to evaluate the influence of the time of cutting on the nutritive value of Piatã silage grass in monocrop and intercropping with sorghum for cutting and grazing. We used a randomized block design with four replications. Treatments were arranged in a split plot design, with systems as plots (Piata grass, sorghum for cutting and grazing, and intercropping), cutting ages as sublots (70, 90, and 110 days after sowing). The minisilos were opened at 46 days to evaluate silage crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), total digestible nutrients (TDN), ammonia nitrogen, lignin, and pH. We observed significant interaction between system and age on the variables CP, ADF, NDF, lignin and pH. With the advancement of age, there was a linear reduction in crude protein content of 0.12, 0.08, and 0.16 percentage units for each day after sowing in sorghum silage, sorghum grass and grass + Piata, respectively. There was a linear increase in the pH value of sorghum silage + grass due to the advancement of age of 0.03 units for each day after sowing. In sorghum silage and monocrop grass, the pH did not vary with the cutting age, with values of 4.63 and 5.20, respectively. Sorghum systems showed potential for the production of good quality silage at 70 days of age.

摘要 本研究旨在评估刈割时期对单作及与高粱间作、用于刈割和放牧的皮亚特草（Piatã grass）青贮营养价值的影响。本试验采用随机区组设计，设置4次重复。处理采用裂区设计，以种植系统为主区（皮亚特草、专用刈割与放牧的高粱，以及二者间作体系），以播后刈割天数为副区（播后70、90、110 d）。于青贮发酵46 d时打开微型青贮窖，测定青贮料的粗蛋白（CP）、酸性洗涤纤维（ADF）、中性洗涤纤维（NDF）、总可消化养分（TDN）、氨态氮、木质素及pH值。结果表明，种植系统与刈割天数对粗蛋白、酸性洗涤纤维、中性洗涤纤维、木质素及pH值存在显著交互效应。随着刈割天数增加，专用刈割与放牧的高粱青贮、单作皮亚特草，以及皮亚特草与高粱间作体系的粗蛋白含量分别以每日0.12、0.08、0.16个百分点的速率线性下降。皮亚特草与高粱间作青贮的pH值随刈割天数增加呈线性升高，播后每增加1 d，pH值升高0.03个单位。而专用刈割与放牧的高粱青贮及单作皮亚特草青贮的pH值不受刈割天数影响，分别稳定在4.63和5.20。在播后70 d时，高粱种植体系可生产出高品质青贮料，具备良好应用潜力。