α-淀粉酶对不同NSC含量稻草青贮品质的影响

适时收获的新鲜稻草中含有相当数量的非结构性碳水化合物(NSC),其中淀粉占有相当比例。淀粉在青贮中需水解成可溶性糖(WSC)才能被大部分乳酸菌利用。本研究选用两个稻草中NSC含量差异显著的水稻品种(杂交籼稻两优培九和常规粳稻武香粳14),设置0.5,1.0和1.5g/kg的3个α-淀粉酶添加浓度和对照(无添加)进行试验,研究不同的α-淀粉酶添加浓度对稻草青贮品质的影响,为改善稻草饲用品质提供依据。结果表明,两优培九稻草中的NSC含量为6.89%,淀粉含量为3.68%,显著低于武香粳14稻草中的NSC(16.51%)和淀粉(10.63%)含量(P0.05);添加不同浓度的α-淀粉酶后青贮稻草的饲用品质和发酵品质间存在显著差异(P0.05),两优培九以1.5g/kg的α-淀粉酶添加浓度效果最好,武香粳14以1.0g/kg的添加浓度效果最好;武香粳14稻草添加α-淀粉酶的青贮效果显著优于两优培九。添加α-淀粉酶后两优培九稻草中的NSC、WSC和淀粉含量,以及武香粳14稻草中的NSC和淀粉含量均呈持续下降趋势,而武香粳14稻草中的WSC含量则呈"降-升-降"变化趋势;添加α-淀粉酶处理组的WSC含量在青贮第3天时较青贮第2天均有不同程度上升,并显著高于对照;但在青贮第5~14天期间,WSC含量大幅下降,与对照组差异减小。

Effects ofα-amylase on fermentation of rice (Oryza sativa)straw

Rice (Oryza sativa )straw harvested at the appropriate time to achieve good nonstructural carbohy-drate content (NSC)was utilized in this study;the main NSC was starch.Starch in rice straw should be initially hydrolyzed into water soluble carbohydrates (WSC)which are able to be utilized by lactic acid bacteria during the ensiling process.Two rice varieties (hybrid indica rice,variety Liangyoupeijiu and common japonica rice,variety Wuxiangjing 14)containing different NSC in the straw were treated with four different concentra-tions of α-amylase (0.5,1.0 and 1.5 g/kg)to investigate the effects ofα-amylase on rice straw silage quality. The results revealed that the NSC and starch content in the straw of Liangyoupeijiu was 6.89% and 3.68%respectively,significantly lower than Wuxiangjing 14 (P <0.05 ),16.51% and 10.63% respectively.The forage quality and fermentation quality of rice straw resulting from differentα-amylase treatments also differed significantly (P <0.05).1.5 g/kg of α-amylase was optimum for Liangyoupeijiu whereas 1.0 g/kg α-amylase was optimum for Wuxiangjing 14.Afterα-amylase application (2-3 days),the NSC,WSC and starch content in the straw of Liangyoupeijiu,and the NSC and starch in the straw of Wuxiangjing 14 decreased,while the WSC in Wuxiangjing 14 increased and was significantly higher than the control.However during the 5th to 14th days of ensiling the WSC content decreased sharply and differences between α-amylase treatments were minimal.