样品前处理方法和试验条件优化对全株玉米青贮中氨态氮含量的影响

Effects of sample pre-treatment methods and experimental conditions optimization on NH_3-N content in whole plant corn silage

本试验旨在研究样品前处理方法和试验条件优化对全株玉米青贮中氨态氮含量的影响,为青贮饲料发酵指标检测提供方法指导。分别将20 g全株玉米青贮样品在不同浸提浓度(90、180 m L和270 m L)、浸提时间(12、24 h和48 h)和浸提温度(4℃、25~30℃室温)条件下处理,然后对不同比色波长和显色稳定性进行氨态氮的测定,筛选出最优条件。结果表明:(1)浸提浓度和浸提温度对全株玉米青贮中氨态氮含量无显著影响(P>0.05),但浸提24 h与浸提48 h比12 h的氨态氮含量分别高46.2%和53.8%(P<0.01)。(2)氨态氮含量随着水浴显色时间的延长显著提高(P<0.01),在30 min时显色达到稳定,最大吸收波长为630 nm;氨态氮回收率为98.81%~104.24%(平均为101.2%)。综上可知,可将20 g全株玉米青贮加入180 m L蒸馏水,4℃低温条件下浸提24 h制成浸提液,在37℃水浴中显色30 min后,630 nm波长下进行测定。

This experiment aimed to investigate the effect of sample pre-treatment methods and experimental conditions optimization on the NH_3-N content in whole plant corn silage,providing methodological guidance for the detection of fermentation indicators in silage.20 g of whole plant corn silage samples were treated at different extraction concentrations(90,180 mL and 270 mL),extraction times(12,24 h and 48 h),and extraction temperatures(4 ℃,25 ~ 30 ℃ room temperature).Then,ammonia nitrogen was measured at different colorimetric wavelengths and color stability,and the optimal conditions were selected.The results showed that:(1) There was no significant difference in the NH_3-N content of the whole plant corn silage between the extraction concentration and extraction temperature(P > 0.05),but the NH_3-N content was 46.2%and 53.8% higher after 24 h and 48 h of extraction compared to 12 h,respectively(P < 0.01).(2) The NH_3-N content significantly increased with the prolongation of the water bath color development time(P < 0.01),and the color development reached stability at 30 minutes,with a maximum absorption wavelength of 630 nm;The recovery rate of NH_3-N was 98.81% ~ 104.24%(with an average of 101.2%).In concluded that 20 g of whole plant corn silage could be extracted in 180 mL of distilled water for 24 h at 4 ℃ to produce an extraction solution.After color development in a 37 ℃water bath for 30 minutes,the determination could be carried out at a wavelength of 630 nm.