苜蓿、玉米青贮饲料有氧稳定性研究

A Study on Aerobic Stability of Alfalfa and Corn Silage

为评价苜蓿(Medicago sativa)和玉米(Zea mays)青贮饲料的有氧稳定性,采用CO2滴定法和微生物培养法,分别对有氧暴露0、2、4、6、8、10 d的苜蓿、玉米青贮饲料,以及有氧暴露0、2、4 d的苜蓿青贮饲料和玉米青贮饲料的全混合日粮有氧稳定性进行分析与测定。结果表明:苜蓿青贮饲料在有氧暴露10 d时pH升高0.38,玉米青贮饲料则升高0.60;有氧暴露4d时,苜蓿青贮饲料CO2产量低于1 g/kg.DM,而玉米青贮饲料则高达5.4 g/kg.DM;苜蓿青贮饲料的酵母菌和霉菌数量从1.58×102CFU/g.DM和2.51×102CFU/g.DM显著增加到2.51×103CFU/g.DM和7.94×102CFU/g.DM(P<0.05),而玉米青贮饲料在有氧暴露2 d时即从2.51×102CFU/g.DM和1.26×102CFU/g.DM显著提高到3.98×103CFU/g.DM和3.16×103CFU/g.DM(P<0.05);这说明苜蓿青贮饲料的有氧稳定性要优于玉米青贮饲料;在有氧暴露的4d内,虽然苜蓿青贮饲料全混合日粮的pH变化为0.93,低于玉米青贮饲料2.18,但酵母菌和霉菌的数量无明显差异,在有氧暴露2 d后均显著地增加(P<0.05)。

When exposed to air in feedlot, the silage quality and nutrient value will be decreased due to aerobic microbe proliferation in silage. This experiment was carried out to evaluate the aerobic stability of the alfalfa and corn silages which were exposed to air and sampled on 0, 2, 4, 6, 8, and 10 day and their total mixed ration sampled on 0, 2, and 4 day using the methods of CO2 titration and microbial culture. After 10-day exposure to air, the pH of alfalfa silage increased 0.38, while 0.60 for corn silage. After 4-day exposure to air, the CO2 production of alfalfa silage was less than 1 g/kg · DM, while more than 5.4 g/kg · DM for corn silage; the numbers of yeast and mold increased significantly （P〈0.05） from 1. 58 × 10^2 CFU/g · DM and 2.51×10^2 CFU/g · DM to 2.51× 10^3 CFU/g · DM and 7.94× 10^2 CFU/g · DM, respectively, while those of corn silage, when exposed to air 2 days, increased significantly （P〈0.05） from 2.51× 10^2 CFU/g · DM and 1.26 × 10^2 CFU/g ·DM to 3.98× 10^3CFU/g ·DM and 3.16 × 10^3CFU/g · DM（P〈0. 05） when exposed to air 2 days.