关键词: 饲料, 含氮量, 杜马斯燃烧法, 凯氏定氮法

Abstract: This study was conducted to examine the difference of the N content of 22 N-containing materials, including 5 roughage feeds, 6 high energy feeds and 9 protein feedstuffs, and 2 reference compounds, determined by Kjeldahl (Foss Model 2300, Sweden) and Dumas combustion ( Rapid N III, Elementar，Germany), respectively. Eleven Ncontaining feed samples were dispensed to 3 individual laboratories for N analysis by the two methods，to ensure a quick and no polluted method which can determine the nitrogen content in feedstuffs. The result showed that there was a linear correlation (r =0.999 8，P<0.001) of N contents between the two determination methods. Most protein and high energy feedstuffs had no significant difference(P>0.05,CV<5%), but a significant difference（P<0.05，CV<5%）was obtained in 4 roughage feedstuffs. With the Kjeldahl determination, the N content of 7 samples were significantly different (P<0.05) among 3 laboratories, having more than 5% of CV for 2 samples. Unlike the Kjeldahl method, however, the Dumas combustion method produced a significant difference (P<0.05) in the N determination of only 2 samples, with less than 5% of CV values for all feed samples among the 3 laboratories. The N content CV values obtained from the 3 laboratories in 11 samples were higher (P<0.01) with Kjekldahl method than those with Dumas combustion method. It was concluded that Dumas method can be used as a regular method for determination of nitrogen contents in feedstuffs or diets.

Key words: feedstuff, nitrogen content, Dumas combustion, Kjeldahl N analysis