【摘要】 本试验采用3头(120±5)日龄、体重为(72±2)kg的荷斯坦公犊牛,通过调整日粮营养水平来观察其尿中嘌呤衍生物(PD)的排出规律,比较其与成年反刍动物之间的差异,考察犊牛期能否用尿嘌呤衍生物法来估测瘤胃微生物蛋白。试验设计3种营养水平日粮,采用随机区组试验设计。结果发现,犊牛尿中嘌呤衍生物中尿酸大约为50%～75%,而在成年反刍动物尿酸不到15%。PD的排出量随可消化有机物(DOM)和可消化粗蛋白(DCP)进食量升高而上升,存在弱的相关性(R2=0.76,n=9)。其排出水平为0.12～0.24mmol/(BW0.75·d)。作为估测成年反刍动物微生物蛋白合成量的另一个指标[PD]×BW0.75/[C](其中[PD]为嘌呤衍生物浓度,[C]为尿中肌酐酸浓度,BW0.75为代谢体重,简称PDC),与DOM和DCP进食量存在负相关,这与成年反刍动物的研究结果是相反的。更多还原

【Abstract】 Three(120±5) days old Holstein male calves with a mean body weight of (72±2) kg were fed three mixed diets of forage and concentrate. In this experiment, a randomized complete block design was used to research the rules of purine derivatives excretion through observing the relationship between DOMI intake and PD excretion. Due to the difference in purine digestion and metabolism physiology between the calves and cattle, the uric acid, which only takes little part in cattle, was the main part (about 50%～75%) in the calves’ urine. The PD excretion changed from 0.12 to 0.24 mmol/(BW 0.75 ·d) with the enhancement of DOM and DCP intake, but the relativity was not significant( R 2 = 0.76 , n =9). At the same time, the creatine excretion(0.09～0.55 mmol/(BW 0.75 ·d) increased straightly with the increase of DOM and DCP intake, but the PDC index decreased when the DOMI increased, which was contrary to that of cattle.更多还原