饲草玉米不同生育期的产量、品质和青贮利用研究

对墨西哥大刍草、玉草3号和玉草6号3种不同类型饲草玉米在孕穗期、抽雄期和吐丝期的产量、青贮品质及其营养价值进行了分析。结果表明:品种和生育期对鲜、干草产量有显著影响,而二者之间的交互作用对鲜、干草产量影响不显著;3个品种鲜、干草产量均在吐丝期最高,其中,玉草6号鲜、干草产量极显著高于玉草3号和墨西哥大刍草。从抽雄期及以后,所有饲草玉米干物质(DM)含量均达20%以上,符合青贮对水分的要求。粗蛋白(CP)含量从孕穗期到吐丝期逐渐降低,变幅为8.19%DM~12.80%DM;各时期CP含量均以玉草6号最高,玉草3号和墨西哥大刍草CP含量差异较小。可溶性糖(WSC)含量在孕穗期最高,纤维含量随生育期延长均呈上升趋势。青贮发酵品质在不同生育期差异显著,孕穗期pH值为3.69,乳酸(LA)含量为7.00%DM,发酵品质最优。品种主效应分析表明,玉草6号发酵品质最好,玉草3号和墨西哥大刍草差异不显著。综合分析品种和生育期对青贮发酵品质和营养成分的影响,玉草6号在孕穗期青贮,相对饲用价值达103.28,发酵品质和营养价值最好;玉草3号和墨西哥大刍草在抽雄期青贮发酵品质和营养价值最佳。

Forage maize type and growth stage effects on biomass yield and silage quality

In this study, biomass yield and silage quality of three different varieties of forage maize (Zea mexicana, Yucao No.3 and Yucao No.6) were measured at the booting, tasseling and silking stage. Yields differed significantly, both between varieties and growth stages, but no variety by growth stage interaction was observed for yield. The fresh and dry matter (DM) yields of the three varieties were highest at the silking stage of crop development. Among the varieties, Yucao No.6 had significantly higher fresh and DM yield than Yucao No.3 and Z. mexicana. From the tasseling stage onward, the DM content of the varieties tested was greater than 20%, which meets the moisture requirement for silage making. The crude protein (CP) content ranged between 8.19% DM-12.80% DM and decreased gradually from the booting stage to the silking stage. Yucao No.6 had the highest CP content at every growth stage tested, while the CP difference between Yucao No.3 and Z. mexicana was not significant. Water soluble carbohydrate content was highest at the booting stage, and the content of acid detergent fiber and neutral detergent fiber increased progressively at successive crop development stages. The fermentation quality of silage differed significantly between maize varieties and growth stages, with a significant interaction between variety and growth stage. Silages from all the tested forage maize varieties, made in laboratory silos, had the lowest pH value (3.69) and the highest lactic acid content (7.00% DM) when harvested at the booting stage. Silage made at the booting stage performed better in fermentation analysis than silage made at tasseling or booting. Hence, the booting stage is recommended as the best stage for harvesting forage maize for silage production, where quality is required. With regard to variety differences in fermentation analysis, Yucao No.6 performed better than Yucao No.3 and Z. mexicana in almost all parameters studied. Based on the interaction between variety and growth stage for silage fermentation and nutrient composition, Yucao No.6 at booting stage was identified as best for silage due to its high forage fermentation quality and nutritional value compared to the two other varieties and their respective growth stages. However, Yucao No.3 and Z. mexicana were better for production of silage with good fermentation characterisitics, when harvested at the tasseling stage.