日粮氮源结构对阉牛氮代谢及瘤胃发酵影响的研究

EFFECT OF DIETARY NITROGEN SOURCE STRUCTURE ON NITROGEN METABOLISM AND RUMEN FERMENTATION OF STEERS

采用安装瘤胃瘘管的西门塔尔改良架子牛阉牛3头 ,通过4×3不完全拉丁方设计 ,系统研究了4种不同氮源结构的日粮对阉牛消化代谢、微生物蛋白合成、N利用和瘤胃发酵的影响。结果表明 ,3组以玉米酒精糟 (CDDG)和尿素为主要N源的试验日粮随着RDP水平的增加其微生物蛋白产量、尿N排出量和乙酸/丙酸比有所增加 ,N沉积率亦随UDP的增加而增加。对照组豆粕型日粮的DM和OM的消化率高于试验组 ,微生物蛋白产量显著高于试验组 (P<0.01) ,但尿N高于试验组且N沉积率低于试验日粮A和B。对照组豆粕型日粮的瘤胃固相食糜流通率显著高于其它各组 (P<0.05) ,各处理对TVFA和 pH值无显著影响。对照组豆粕型日粮的NH3-N浓度最高且显著高于试验日粮A组 (P<0.05)。

A 4×3 Latin Square experiment was carried out to study the effect of dietary nitrogen source structure on digestion and metabolism, microbic protein yield, nitrogen availabilities and rumen fermentation of steers. The results showed that microbic protein yield, urea N and Ac/Pr ratio were increased by increasing dietary RDP level in 3 experimental diets. Apparent nitrogen deposition was increased by increasing dietary UDP level in the experimental diets. Control diet had greater apparent digestibility of DM and OM,urine N outputs than experimental diets, especially for microbic protein yield (P<0.01). But control diet had lower apparent nitrogen deposition than experimental diet A and B. Rumen fractional DM outflow rate was greater significantly for control diet than for the experimental diets (P<0.05). Control diet also had greater rumen NH3-N concentration than experimental diet A (P<0.05).