Teller E, Godeau J M
Arch Tierernahr. 1986 Jun;36(6):541-50. doi: 10.1080/17450398609421058.
Starea, an intimate mixture of gelatinized wheat starch and urea, was tested again urea with regard to the ammonia release in the rumen, the amount and composition of the nitrogen fraction reaching the intestine, the nitrogen and energy balances, and the performance of lactating cows. Maize silage was the basal feed in all experiments. The ammonia concentration in the rumen liquor was measured in two cows fitted with a permanent rumen cannula. The curve of the ammonia concentration was about the same with both nitrogen supplements, and peaked at about 250 mg/l (14.7 mmol/l) two hours postfeeding. Two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus were fed with maize silage supplemented with increasing amounts of either urea or starea. The duodenal nitrogen flow rapidly levelled off with both supplements and no significant difference between them could be detected. The amount of ammonia in the duodenal digesta remained very low. Nitrogen digestibility measured in lactating cows was not noticeably affected when starea instead of urea was added to maize silage. However, nitrogen excretion in the urine tended to decrease, while nitrogen secretion in milk was augmented with starea. The digestibility of the rations and their metabolizable energy supply were not significantly affected, and milk production was quite the same with both supplements, apart from the higher amount of milk protein obtained with starea compared with urea. As a general conclusion from the whole work conducted on the nutritive value of urea for lactating cows, it can be stated that the decline in performance of the animals after substitution of urea for conventional protein is mainly due to a decrease of the metabolizable energy concentration in the diets. None of the attempts tested in an effort to improve the nutritive value of urea was able to overcome this difficulty.
Starea是一种由糊化小麦淀粉和尿素组成的紧密混合物，就瘤胃中氨的释放、到达肠道的氮部分的数量和组成、氮和能量平衡以及泌乳奶牛的生产性能而言，再次对其与尿素进行了测试。在所有实验中，玉米青贮饲料是基础饲料。在两头装有永久性瘤胃瘘管的奶牛中测量瘤胃液中的氨浓度。两种氮源补充剂的氨浓度曲线大致相同，在喂食后两小时达到峰值，约为250毫克/升（14.7毫摩尔/升）。给两头在距幽门10厘米处装有再入式瘘管的干奶牛喂食添加了越来越多尿素或Starea的玉米青贮饲料。两种补充剂的十二指肠氮流量迅速趋于平稳，未检测到它们之间有显著差异。十二指肠消化物中的氨含量仍然很低。当在玉米青贮饲料中添加Starea而非尿素时，泌乳奶牛的氮消化率没有明显受到影响。然而，尿液中的氮排泄量有下降趋势，而Starea使牛奶中的氮分泌增加。日粮的消化率及其可代谢能量供应没有受到显著影响，两种补充剂的产奶量相当，只是与尿素相比，Starea获得的牛奶蛋白量更高。从对泌乳奶牛尿素营养价值所做的全部工作得出的总体结论是，可以说用尿素替代传统蛋白质后动物生产性能下降主要是由于日粮中可代谢能量浓度降低。为提高尿素营养价值所测试的任何尝试都未能克服这一困难。
