双乙酸钠对苜蓿青贮品质、营养成分及蛋白分子结构的影响

Effects of sodium diacetate on the quality, nutrient composition and protein molecular structure of alfalfa silage

为了促进节粮型畜牧业发展,为反刍动物提供优质青贮饲料。研究了添加剂(双乙酸钠)在紫花苜蓿青贮中的最佳作用剂量,通过在青贮过程中添加不同浓度的双乙酸钠,探究其对苜蓿青贮发酵品质、营养特性以及蛋白质分子结构的影响。选用6月初第一茬刈割的初花期金皇后紫花苜蓿为原料进行青贮,试验组依据双乙酸钠的添加水平设0(对照),0.1%、0.2%、0.3%、0.4%、0.5%、0.6%和0.7%共8个处理组,在常温下贮藏45 d后测定相关指标。测定结果如下:添加双乙酸钠组苜蓿青贮饲料pH值显著低于对照组(P<0.05),中性洗涤纤维和酸性洗涤纤维含量也显著降低,感官评分试验组均优于对照组。双乙酸钠添加量为0.7%时,蛋白质含量最高,丙酸、丁酸及氨态氮含量最低;酰胺Ⅰ、Ⅱ区的峰高及峰面积显著降低,α-螺旋区与β-折叠区中心高度比显著升高。这表明添加双乙酸钠能显著改善青贮苜蓿的营养特性、发酵品质以及蛋白质分子结构。综合本试验数据及经济成本考量,双乙酸钠最佳添加量为0.5%~0.6%。

This research investigated the optimal concentration of sodium diacetate when used as an additive in alfalfa silage production.Such technology is valuable to provide forage of superior nutritive value and enhance economic performance and development of ruminant livestock industries.An alfalfa crop(cv.Golden queen)at early flowering growth stage in the first harvest in early June was divided into eight parts and ensiled in laboratory mini-silos with sodium diacetate added to each at different rates of 0%(Control),0.1%,0.2%,0.3%,0.4%,0.5%,0.6%and 0.7%by weight.After 45 days fermentation at room temperature,the silage quality,nutritional properties,and protein molecular structure differences of the eight silages were evaluated.The results were as follows:the pH value,and neutral and acid detergent fiber contents of the sodium diacetate-treated silages were significantly lower than those of the Control treatment(P<0.05),and the sensory score of treated silages was better than that of the Control treatment.Compared with the Control silage and the other silages treated at lower rates,the addition of 0.7%sodium diacetate resulted in the highest protein content,and the lowest contents of propionic acid,butyric acid and ammonia nitrogen.In addition,protein structure evaluation indicated that the peak height and peak areas of the amideⅠandⅡregions were significantly decreased,and the ratio of theα-helical region height to theβ-fold region height was significantly increased.This study indicates that the addition of an appropriate amount of sodium diacetate in silage production significantly improves the nutritional quality,fermentation quality and protein molecular structure of alfalfa silage.Balancing silage quality improvement against economic cost considerations,the data indicate that the optimum dosage of sodium diacetate is 0.5%-0.6%.