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A feeding experiment was carried out in which adult ewes of the Ethiopian Highland Menz breed grazed on meadow pasture were supplemented with urea-molasses block and/or noug cake. There was low consumption of urea-molasses block (67 gd-1) and its contribution to total nitrogen requirement was minimal. Dietary treatment had no significant effect on liveweight changes of ewes, their reproductive performance and performance of the lambs. When there was liver fluke infection, ewes and their lambs which were supplemented with urea-molasses block and/or noug cake had better survival compared to those which did not get any supplements (35% mortality vs 55%). The rumen ammonia-N concentration was significantly lower in the control sheep (11 mg/100 ml) and those that received only urea-molasses (14 mg/100 ml) and highest in sheep receiving the urea-molasses block and noug cake (26 mg/100 ml). The volatile fatty acid proportions were not significantly affected by the diets. Low level of urea-molasses block consumption seemed to be a main factor limiting the usefulness of the urea-molasses block and it is recommended that factors likely to enhance its consumption be investigated. 相似文献
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Experiments were performed by the method of the extracorporeal perfusion of sheep rumen lasting 150 minutes. After 60 minutes of perfusion, 20 g of enzymatic casein hydrolyzate were applied to the rumen. Ammonia, urea, and total nitrogen were determined in the samples of perfusate, and ammonia and pH were determined in the rumen content. Considerable amounts of ammonia accumulated in the perfusate in the course of the experiment. At the end of perfusion, the concentration of NH3-N reached an average value of up to 12 mg per 100 ml. The level of urea in the perfusate decreased only in the first phase of perfusion (before the application of casein hydrolyzate to the rumen) and remained unchanged in the subsequent phase. It is assumed that part of urea-N from the perfusate after urea hydrolysis, taking place already in the rumen wall, returned to the perfusate in the form of ammonia. In the first phase of perfusion the passage of nitrogen from the blood into the rumen took place, in the second phase its absorption from the rumen into the blood was observed. The urea-N ratio from the passage of total nitrogen into the rumen ranged between 4.63% and 13.84%, but the concentration of total nitrogen in the perfusate decreased by 7-15% and that of urea nitrogen by 37-42%. It follows from the results that a major part of endogenous nitrogen passing from perfusate to the rumen was represented by proteins and/or their peptidic splits. 相似文献
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The metabolism of amino acids and urea in an isolated perfused wall of sheep rumen was studied by the method of organ perfusion, using 3 kinds of perfusate. In experiments with semisynthetic perfusate containing urea (SPurea) the levels of lysine, valine, glutamic acid and alanine increased at a simultaneous decrease of levels of leucine, arginine, aspartic acid, threonine and methionine. In perfusions with the semisynthetic medium without urea (SP) the levels of lysine, valine, phenylalanine, isoleucine, glutamic acid, glycine and alanine increased, the level of threonine dropped. In perfusions with whole autologous blood (KP) the levels of valine, glutamic acid and alanine increased, the level of arginine decreased. The level of urea decreased sharply at using SPurea and KP, however, the equal cumulation of ammonia (200-400 mumol x 1(-1)) was found in all three types of perfusate after 2-hr perfusion. Moreover, in experiments with SP a low level of urea was found already after 5-min. of perfusion. The results of the experiments suggest that the rumen wall is capable of producing amino acids also without the contents of rumen, and that independently on the presence or absence of urea as a nitrogen source. 相似文献
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蚕豆不同部位左旋多巴(L-Dopa)含量研究 总被引:2,自引:0,他引:2
采用HPLC法测定蚕豆不同品种的花、茎、叶片、荚壳、种皮、子叶中L-Dopa的含量和不同颜色蚕豆花L-Dopa含量,以及蚕豆花不同烘干温度对L-Dopa含量的影响。结果表明,蚕豆不同部位L-Dopa含量以花中最高,子叶中含量最低,含量高低顺序为:花>叶片>荚壳>茎>种皮>子叶;91份蚕豆品种不同花色蚕豆花L-Dopa含量高低顺序为:白花>浅紫>紫色,表现出随花色加深,L-Dopa含量下降的趋势;100℃烘干的蚕豆花L-Dopa含量仅为40℃烘干的60%,显示高温烘干L-Dopa含量显著减少。 相似文献