This study was conducted to evaluate the nutritional values of Elymus sibiricus Linn at different growing stages by the methods of in vitro gas production and Cornell net carbohydrate and protein system ( CNCPS) . Gas production and fermentation parameters were determined by in vitro gas production method during heading, flowering, filling and milk ripe stages, respectively. The CNCPS component contents were de-termined, and the correlation between the two methods was analyzed. The results showed as follows:1) with the growing of Elymus sibiricus Linn, crude protein ( CP) and soluble protein ( SOLP) contents decreased, neutral detergent fiber ( NDF ) , acid detergent fiber ( ADF ) and acid detergent lignin ( ADL ) contents in-creased, and NDF insoluble protein ( NDFIP) and ADF insoluble protein ( ADFIP) contents decreased; the differences between heading and flowering stages compared with filling and milk ripe stages were significant ( P<0.05) . 2) After 72 h in vitro fermentation, gas production of flowering stage was significantly greater than other stages ( P<0.05) . 3) With the growing of Elymus sibiricus Linn, in carbohydrate ( CHO) components, the contents of CHO and slowly degraded carbohydrate (CB2) increased, while those of rapidly degraded car-bohydrate ( CA) and nonstructural carbohydrate ( CNSC) showed an opposite tend; in protein components, unavailable protein ( PC) content at heading stage and non-protein nitrogen ( PA) content at flowering stage were significantly higher than the other stages (P<0.05). 4) CNSC, CA, intermediately degraded carbohy-drate (CB1), CB2, unavailable fiber (CC), PA, slowly degraded true protein (PB3) and PC contents were correlated with the gas production at different time point ( P<0.05 or P<0.01) , and regression equations were set up. In conclusion, flowering stage of Elymus sibiricus Linn has the highest nutritional value, followed by the heading, filling, and milk ripe stages, and it is able to estimate the feed CNCPS component using in vitro gas production method.%本试验旨在利用体外产气法及康奈尔净碳水化合物和蛋白质体系( CNCPS)对不同生育期老芒麦营养价值进行评定。采用体外产气法测定抽穗期、开花期、灌浆期、乳熟期4个生育期老芒麦的体外发酵产气量及发酵参数；用CNCPS测定相应组分含量,评价老芒麦营养价值；并比较研究体外产气法和CNCPS 2种方法评价结果的相关性。结果表明：1)随着老芒麦的生长,粗蛋白质( CP)和可溶性蛋白质( SOLP)含量降低,中性洗涤纤维( NDF)、酸性洗涤纤维( ADF)和酸性洗涤木质素( ADL)含量增加,中性洗涤不溶性蛋白质( NDFIP)、酸性洗涤不溶性蛋白质(ADFIP)含量减少,抽穗期和开花期与灌浆期和乳熟期差异显著(P<0.05)。2)体外发酵至72 h结束时,产气量以开花期最高,显著高于其他各期( P<0.05)。3)随着老芒麦的生长,碳水化合物(CHO)组分中,CHO、缓慢降解碳水化合物(CB2)含量呈递增趋势,而快速降解碳水化合物( CA)、非结构性碳水化合物( CNSC)含量则相反；蛋白质组分中,抽穗期的不可利用蛋白质(PC)和开花期的非蛋白氮(PA)含量显著高于其他生育期(P<0.05)。4)CNSC、CA、中速降解碳水化合物(CB1)、CB2、不可利用纤维(CC)、PA、慢速降解真蛋白质(PB3)、PC含量分别与不同时间点产气量存在显著或极显著的相关性( P<0.05或P<0.01),通过这几种组分与体外产气量的相关性建立了回归关系。综上所述,老芒麦于开花期营养价值最高,抽穗期、灌浆期和乳熟期依次次之,体外产气法和CNCPS评价牧草价值具有相关性,用体外产气量估测牧草CNCPS组分具有可行性和实用价值。
展开▼
