Voigt J, Piatkowski B, Krawielitzki R, Bergner H, Görsch R
Arch Tierernahr. 1981 Jan;31(1):45-56. doi: 10.1080/17450398109425105.
In 3 experiments 2 lactating dairy cows received a mixed ration consisting of 10 kg maize silage, 2.5 kg hay, 2.0 kg barley, 1 kg dried sugar-beet pulp, 1.5 kg maize starch, 0.5 kg sugar, 0.2 kg of a mineral-vitamin mixture and 0.08 kg non-protein nitrogen (NPN) per animal and day. The ration contained 8.3 kg dry matter, 5.1 kEFU cattle and 1.18 kg crude protein, 0.5 kg of which from NPN, and was given in equal shares twice a day. Urea (I) or isobutylidene diurea (IBDU), to which the animals were not adapted (II) resp. adapted (III), were the sources of NPN.IBDU proved to a be a very slow source of NH3 in the rumen. 2 hours after the intake of NPN 48 . . . 75, 5 . . . 9 and 5 . . . 12 mg NH3/100 ml could be detected from I to III. Up to the third hour the concentration of IBDU and urea increased in III, which is due to the slow distribution of the slowly soluble IBDU in the fluid digestaphasis. 12 hours after the feeding the level of IBDU and urea in III still amounted to 25 mg urea/100 ml, in I to 1 mg/100 ml only. In the first 3 hours after supplying the NPN the pH-value of I was more than 1 unit higher than that of II and III. There were no significant differences in the fermentation models between the variants, the concentration of volatile fatty acids was 12.6, 12.3 and 11.1 mmol/100 ml. In the stomachs the digestibility of the organic matter was 52, 51 and 54%, that of the crude cellulose 64, 62 and 66% and that of the starch 91, 93 and 98%. At the duodenum the passage rate of N was 87 . . . 93, 107 . . . 126 and 96 . . . 130% of the N-intake, that of NH3-N 6, 43 and 22 g per day and that of bacteria-N 61 . . . 76, 78 . . . 100 and 76 . . . 96% of the N-intake. 2.3 . . . 2.8, 2.6 . . . 3.2 and 2.1 . . . 3.1 g bacteria-N were formed per 100 g dry matter fermented in the rumen. In the intestines 55 . . . 61, 57 . . . 64 and 48 . . . 71% of the feed-N were available as non-NH3-N. The conclusion is that in comparison to urea and concerning IBDU, the rumeno-hepatic circulation plays a definitely bigger role for the N-supply of the rumen microbes and that the possibility of the better N-utilisation can be derived from that.
在3项试验中，2头泌乳奶牛每头每天采食由10千克玉米青贮、2.5千克干草、2.0千克大麦、1千克干甜菜粕、1.5千克玉米淀粉、0.5千克糖、0.2千克矿物质 - 维生素预混料和0.08千克非蛋白氮（NPN）组成的混合日粮。该日粮含8.3千克干物质、5.1个奶牛能量单位（kEFU）和1.18千克粗蛋白，其中0.5千克来自NPN，日粮分两次等量投喂。NPN的来源分别为尿素（I）、动物未适应的异丁叉二脲（IBDU）（II）和适应的异丁叉二脲（III）。结果表明，IBDU是瘤胃中非常缓慢的氨源。采食NPN后2小时，从I到III每100毫升可检测到48……75、5……9和5……12毫克氨。在III组中，直至第3小时，IBDU和尿素的浓度都在升高，这是由于难溶性IBDU在液相消化阶段分布缓慢所致。采食12小时后，III组中IBDU和尿素的水平仍达25毫克尿素/100毫升，而I组仅为1毫克/100毫升。在供给NPN后的前3小时，I组的pH值比II组和III组高1个多单位。各处理间发酵模式无显著差异，挥发性脂肪酸浓度分别为12.6、12.3和ll.l毫摩尔/100毫升。在瘤胃中，有机物消化率分别为52%、51%和54%，粗纤维素消化率分别为64%、62%和66%，淀粉消化率分别为91%、93%和98%。在十二指肠，氮的通过率分别为氮摄入量的87……93%、l07……126%和96……130%，氨态氮每天排出量分别为6克、43克和22克；细菌氮通过率分别为氮摄入量的61……76%、78……100%和76……96%。每100克在瘤胃中发酵的干物质可生成2.3……2.8克、2.6……3.2克和2.1……3.1克细菌氮。在肠道中，饲料氮的55……61%、57……64%和48……71%以非氨态氮形式存在。结论是，与尿素相比，就IBDU而言，瘤胃 - 肝脏循环对瘤胃微生物的氮供应起着更大的作用，由此可以更好地利用氮。
