^(15)N示踪法对日粮不同蛋白质水平山羊氮代谢的影响

Effects of different ration protein levels on metabolism of nitrogen in goat with the ^(15)N trace technique

采用15N稳定性同位素示踪技术,将4只(30±3)kg、装有颈静脉血管插管的山羊,按4×4拉丁方设计进行试验,研究了由牧草和精料组成的4种不同蛋白质水平日粮[8.5%(A)、11.0%(B)、13.5%(C)和16.0%(D)]对山羊内源尿素氮代谢的影响。结果表明,日粮蛋白质水平对氮的表观消化率影响较小,各组间差异不显著,但呈现出随氮食入量的增加而升高的趋势;对山羊体内氮的沉积量有显著或极显著的影响,当日粮蛋白质水平为11.0%时,可获得最大氮沉积量0.36g/(d·W0.75)。粪中15N丰度和富集量都呈现出随日粮蛋白质水平的升高先上升而后下降的趋势,尿中15N丰度和富集量都呈现出随日粮蛋白质水平升高而升高的趋势,日粮蛋白质水平对粪和尿中15N峰值出现的时间均影响不大。

Four goats fitted with jugular fistulae with body weight of （30±3）kg were used as experimental animals,a 4×4 Latin Square experiment using ^15N stable tracer technique was carried out to study the effect of ration protein levels on metabolism of nitrogen in goat.Four different ration protein levels were 8.5 %（A）,11.0 %（B）,13.5 %（C）and 16.0 % （D）,respectively.The results showed that：the apparent digestilities of nitrogen increased with the increase of ration protein levels,but there were no significant differences in the four groups （P 〉 0.05）.The retained nitrogen （RN）in B group was much higher than that in A group（P 〈 0.01）and C,D group（P 〈 0.05）.The highest retained nitrogen 0.36 g/（d·W^0.75） was observed in the protein level of 11.0 %.The abundance and enrichment of feces-^15N increased to the highest levels then decreased with the increase of ration protein levels,the abundance and enrichment of urine-^15N showed an increasing trend with the increase of ration protein levels.The ration protein levels had no effects on the appearing time of the abundance of feces and urine respectively.