青稞秸秆替代苇状羊茅对全混合日粮青贮早期发酵品质及有氧稳定性的影响

本试验旨在研究不同比例青稞秸秆替代苇状羊茅对全混合日粮青贮早期发酵品质及有氧稳定性的影响。试验设对照组(TH₀)和3个青稞秸秆不同比例替代组TH₅、TH₁₀和TH₁₅。青贮14 d开窖取样,分析其发酵品质、化学成分及微生物数量,将剩余的发酵TMR暴露于空气,用多通道温度记录仪记录温度变化;并分别在有氧暴露的第2,5和8天取样评定其有氧稳定性。结果表明,与对照组(TH₀)相比,TH₅的pH、乳酸、乙酸、总挥发性脂肪酸和乙醇含量无显著(P>0.05)差异;TH₁₀和对照相比pH差异不显著(P>0.05),但乳酸、乙酸、总挥发性脂肪酸和乙醇含量显著(P<0.05)低于对照组;TH₁₅ pH显著(P<0.05)高于对照组,乳酸、乙酸、总挥发性脂肪酸和乙醇含量显著(P<0.05)低于对照组;各组氨态氮/总氮和乳酸/乙酸无显著(P>0.05)差异,均以乳酸发酵为主,发酵品质良好。有氧暴露第2天后各组pH和氨态氮/总氮持续上升;乳酸、乙酸和水溶性碳水化合物含量持续下降;酵母菌和好氧细菌数量显著(P<0.05)升高。除TH₁₅外,其他各组温度在第35 h开始上升,TH₁₅温度上升延迟,并且温度上升峰值最小。和其他组相比,TH₁₅有氧稳定性最好。综合考虑发酵品质、有氧稳定性及对青稞秸秆资源的最大化利用,建议采用TH₁₅设计配方最为适宜。

Effect of substituting hulless barley straw for tall fescue on early fermentation quality and aerobic stability of mixed-ration silage in Tibet

The objective of this study was to evaluate the effects of substituting hulless barley straw for tall fes-cue at different ratios on the early fermentation quality and aerobic stability of total mixed ration silage in Ti-bet.The experiment consisted of the control (TH0 )and three treatments (TH 5 ,TH 10 ,and TH 15 ).The silos containing these treatments were opened at 14 days after the start of ensiling and the fermentation quality, chemical composition,and microbial communities were analyzed.The aerobic stability of silage samples on the 2nd,5th,and 8th day of exposure to air was evaluated using an online multi-channel data logger temperature recorder.The results showed that the pH,and the contents of lactic acid,acetic acid,total volatile fatty acids (TVFA),and alcohol did not differ significantly between TH 5 and TH0 (P >0.05).The pH of TH 10 was simi-lar to that of TH0 (P >0.05),but the lactic acid,acetic acid,TVFA,and alcohol contents differed significantly between TH 10 and TH0 (P <0.05).The lactic acid,acetic acid,propionic acid,butyric acid,TVFA,and alco-hol contents were significantly lower in TH 15 than in TH0 (P <0.05 ),while the pH of TH 15 was markedly higher (P <0.05)than that of TH0 .The ammonia nitrogen/total nitrogen and lactic acid/acetic acid ratios did not differ significantly (P >0.05)between all treatments and the control.Lactic acid fermentation was domi-nant in all silages and they all had good fermentation quality.During exposure to air,pH and the ammonia ni-trogen/total nitrogen increased in all treatments and the control continued to increase after the 2nd day of expo-sure to air.However,the contents of lactic acid,acetic acid,and water soluble carbohydrates decreased during exposure to air,and the numbers of yeasts and aerobic bacteria increased.The temperatures in TH 5 and TH 10 silages began to increase at 35 h after opening the silos,while the temperature increase was delayed,and was smaller,in TH 15 .Together,these results showed that TH 15 had the best aerobic stability.Taking into account the fermentation quality,aerobic stability,and maximum use of hulless barley straw,the TH 15 treatment was the most suitable choice for silage production.