温度和乳酸菌添加剂对燕麦青贮发酵品质及有氧稳定性的影响

Effects of temperature and lactic acid bacteriaadditives on fermentation quality and aerobicstability of oat silage

摘要:

以乳熟期刈割的燕麦为材料,研究温度和乳酸菌添加剂对其青贮发酵品质及有氧稳定性的影响,设置无添加(对照,CK)、商业青贮添加剂Synlac I(SLI处理)和人工筛选菌株Lactobacillus rhamnosus HT1(HT1处理)3个处理,分别置于25℃、35℃和45℃下青贮60 d后,取样测定青贮燕麦的发酵品质和有氧稳定性。结果表明:随着贮藏温度的升高,燕麦青贮饲料中水溶性碳水化合物和乳酸含量降低,pH和氨氮含量显著升高(P＜0.05)。乳酸菌添加剂能够改善燕麦青贮饲料的发酵品质和有氧稳定性。25℃下,添加剂处理的青贮饲料霉菌和酵母菌数量低于1.00 log10 cfu/g,丙酸和丁酸均未检出。与HT1处理相比较,SLI处理在25℃下效果更好,水溶性碳水化合物、乳酸和挥发性脂肪酸含量更高(P＜0.05),氨态氮和好气性细菌含量较低(P＜0.05)。45℃下则相反,HT1处理效果更优,其水溶性碳水化合物、乳酸和乙酸含量更高,氨态氮、酵母菌和好气性细菌数量较低。且35℃和45℃下HT1处理青贮饲料在有氧发酵阶段pH均小于4.20,有氧稳定性更好。综上所述,HT1处理可以提高燕麦青贮饲料的发酵质量和有氧稳定性,适合用于黄土高原夏季和初秋燕麦青贮饲料调制。

Abstract:

The objective of this study was to evaluate the effects of temperature and lactic acid bacteria on ensiling characteristics and aerobic stability of oat silage.Oats were harvested at dough stage,and silage was prepared with the addition of LAB inoculant Synlac I (SLI) and selected strain Lact.rhamnosus (HT1),with no additive as the control (CK).Then the forages were ensiled at 25℃,35℃ and 45℃,respectively.After 60 days,the fermentation quality and aerobic stability were measured.The result showed that with the increase of ensiling temperature,the content of water-soluble carbohydrate and lactic acid in oat silage reduced,while pH and ammonia-N content significantly (P＜0.05) increased.Lactic acid bacteria additives improved fermentation quality and aerobic stability of oat silage.Molds and yeast counts of additive-treated silage stored at 25℃ were below 1.00 log10 cfu/g of FM;propionic acid and butyric acid contents were below the detection level.Compared with HT1,SLI performed best at 25℃,showing significantly (P＜0.05) higher water-soluble carbohydrate,lactic acid and volatile fatty acid (VFA) content,lower ammonia-N and aerobic bacteria count.When silage was stored at 45℃,HT1 treatment had significantly (P＜0.05) higher content of water-soluble carbohydrate,lactic acid and acetic acid,while lower ammonia-N content,yeast and aerobic bacteria counts than those in the SLI treatment.HT1-treated silages stored at 35℃ and 45℃ showed low pH value (＜ 4.20) during aerobic exposure,which has better aerobic stability.The results confirmed that strain HT1 could improve fermentation quality and aerobic stability of oat silage,therefore it has the potential to be used as inoculant for oat silage production during summer and early autumn in Loess Plateau.