两种牧草在青贮过程中氮转化动力学的比较

Comparison of dynamics of nitrogen transformation in silage of two kinds of forages

为了研究植物酶和微生物活性对青贮牧草蛋白质降解的影响,本试验评估了紫花苜蓿和红花苜蓿在青贮过程中的氮素转化动力学。方法:试验制备了紫花苜蓿和红花苜蓿青贮饲料,并将其平均分为2组,其中1组用放射处理,另1组作为对照,即试验共有4组:未经放射的紫花苜蓿青贮饲料、放射处理的紫花苜蓿青贮饲料、未放射的红花苜蓿青贮饲料和放射处理的红花苜蓿青贮饲料。分别在青贮1、4、8和30 d后进行发酵质量和氮成分分析。结果:放射处理通过提高pH抑制微生物活性,但对发酵产物无显著影响(P>0.05)。除肽氮外,所有氮组分在整个青贮过程中均有增加(P<0.05)。红花苜蓿青贮料与紫花苜蓿青贮料相比,蛋白质水解降低,青贮前期肽氮和游离氨基酸氮的增加量显著降低(P<0.05)。放射处理显著提高了紫花苜蓿青贮第1天的肽氮和氨基酸氮含量(P<0.05),这两种氮元素在未放射的青贮饲料中含量均高于放射处理组(P<0.05)。未放射的紫花苜蓿青贮饲料中氨氮和非蛋白氮含量最高(P<0.05),放射处理的红花苜蓿青贮饲料中氨氮和非蛋白氮含量最低(P<0.05)。结论:红花苜蓿和紫花苜蓿的氮素转化模式不同,特别是在青贮期。微生物活性在蛋白质水解中起一定作用,与紫花苜蓿相比,红花苜蓿受多酚氧化酶的影响较小。

In order to study the effects of plant enzymes and microbial activities on the degradation of protein in forages silage,nitrogen conversion kinetics of alfalfa and red clover in silage was evaluated.Methods:the preparation of the red clover and alfalfa silage feed material storage,and average be divided into two groups,one group treated with radiation,another 1 set as a control,there are 4 groups:without radiation of alfalfa silage,radiation treatment of alfalfa silage,red clover silage without radiation and radiation processing of red clover silage.Fermentation quality and nitrogen composition were analyzed at 1,4,8 and 30 d,respectively.Results:radiation treatment inhibited microbial activity by increasing pH value,but had no significant effect on fermentation products(P>0.05).All nitrogen components except peptide nitrogen increased during the whole silage phase(P<0.05).Compared with alfalfa silage,protein hydrolysis was decreased and the increase of peptide nitrogen and free amino acid nitrogen in the early stage of silage was significantly decreased(P<0.05).The contents of peptide nitrogen and amino acid nitrogen in alfalfa silage on the 1st day were significantly increased by radiation treatment(P<0.05),both of which were higher in unradiated silage than in the radiation treatment groups(P<0.05).The contents of ammonia nitrogen and non-protein nitrogen in unradiated alfalfa silage were the highest(P<0.05),while those in irradiated safflower alfalfa silage were the lowest(P<0.05).In conclusion,the nitrogen conversion patterns of alfalfa and alfalfa are different,especially in silage stage.Compared with alfalfa,safflower alfalfa was less affected by polyphenol oxidase.