旱地栽培小麦及秸秆青贮饲料的发酵特性、营养成分及体外瘤胃降解特性

Fermentation characteristics,nutrient composition and in vitro rumen degradation of wheat and straw silage of dry-land cultivation

本研究总结了全珠小麦青贮饲料和小麦秸秆青贮饲料的保存和营养特性。选择25包来自4个不同田间的全珠小麦青贮饲料和10包小麦秸秆青贮饲料,分别进行了全株小麦青贮和秸秆青贮试验。全珠小麦青贮饲料保存良好,平均pH值为4.46,乳酸、乙酸和丁酸盐的浓度分别为19.2、10.4和4.7g/kg。小麦秸秆青贮饲料的平均pH值为5.46,由于干物质含量较高,发酵受到抑制,乳酸、乙酸和丁酸盐的浓度分别1.9、2.2和1.0g/kg。全株小麦青贮饲料粗蛋白含量为78g/kg,中性洗涤纤维含量为546g/kg,非纤维碳水化合物含量为306g/kg。全珠小麦青贮饲料中粗蛋白和非纤维碳水化合物含量变化较大,中性洗涤纤维含量变化相对较小,这与籽粒成熟度的差异有关。全株小麦青贮饲料和秸秆青贮饲料的体外有机质降解率分别为56.1%和29.3%。全株小麦青贮饲料的体外有机质降解与pH、乳酸和乙酸盐含量无显著相关性(P>0.05),与丁酸盐含量和氨氮比值有显著相关性的趋势(P=0.07)。瘤胃对全珠小麦青贮饲料的发酵早期体外气体生成的变异系数越高,相对于一些纤维组分,如中性洗涤纤维和酸性洗涤纤维,测定的非纤维碳水化合物变异系数也相应升高。综上所述,冬季旱地栽培的小麦可以作为全株青贮饲料在瘤胃中发酵提供能量,小麦秸秆也可以作为纤维原料进行青贮。

The conservation and nutritional characteristics of whole crop wheat silage(WCWS)and wheat straw silage (WSS)were summarized. A total of 25 bales of WCWS and 10 bales of WSS were investigated in this study. Both WCWS and WSS were made in 4 different farm sites. The pH of the WCWS was averaged of pH 4.46,and concentrations of lactate, acetate and butyrate were 19.2, 10.4 and 4.7 g/kg,respectively. The mean pH of WSS was 5.46 and it contained lower acids (1.9, 2.2 and 1.0 g/kg of lactate,acetate and butyrate,respectively),indicating suppressed fermentation due to high dry matter content. The WCWS had crude protein of 78 g/kg and neutral detergent fiber(NDF)of 546 g/kg,and non-fiber carbohydrate (NFC)of 306 g/kg. There was a higher variation in the CP and NFC contents but less variation in the NDF content among the WCWS samples,which as attributed to the difference in the maturity of samples.. The in vitro organic matter degradability of WCWS and WSS were 56.1 and 29.3%,respectively. The in vitro organic matter degradability of WCWS was not significantly correlated with pH and lactate and acetate content(P > 0.05),but had the trend siginificant correlated with butyrate content and NH3-N ratio(P=0.07). The higher coefficient of variation for in vitro gas production at the initial stages of ruminal incubation of WCWS was associated with the observation of higher coefficient of variation for NFC content,compared to those of fiber fractions such as NDF and ADF. In conclusion,winter cropping of wheat as the whole crop silage can supply energy in rumen, and wheat straw also can be useful as fibrous ingredient by ensiling.