Voigt J, Jentsch W, Schönhusen U, Beyer M, Kreienbring F
Forschungsinstitut für die Biologie landwirtschaftlicher Nutztiere, Forschungsbereich Ernährungsphysiologie Oskar Kellner, Rostock, Germany.
Arch Tierernahr. 1993;44(4):369-82. doi: 10.1080/17450399309386081.
In 9 experimental periods on four adult bulls (LW 550 kg) fitted with re-entrant cannulae in the proximal duodenum isoenergetic rations were used on feeding level 1.7 with ground barley, ground maize or fresh potatoes as starch sources. The net energy parts of these concentrates in the ration amounted to 50, 25 and 10%. 50 to 80% of the ration DM consisted of dried grass and about 10% of sugar beet pulp. The dried grass supplied on an average 87, 79 and 62% of the feed crude protein. The intake of DM was 7.74 +/- 0.42 (mean +/- SD) kg/d. The energetic efficiency of microbial N synthesis in the rumen (g N/kg organic matter true fermented in the rumen, TFOM) was averaged 16.4 with a range of 10.6 to 21.4. The microbial efficiency achieved a maximum when the ratio of nitrogen-free extract to crude fibre in the diet was 1.7 and 2.1 with barley, 1.8 with potatoes and 2.1 and 3.3 with corn as starch source. Changes in the microbial efficiency were positively correlated with the rate of passage of non-microbial organic matter from the rumen (g/d) and with the duodenal flow rate (kg digesta/kg DM intake). The relation to the rate of carbohydrate fermentation in the rumen (in %) and to the amount of TFOM (g/d) was negative. The duodenal flow of microbial N and non-ammonia N (g/d) correlated negatively with the organic matter apparently fermented in the rumen (AFOM) and positively with the non AFOM. The amino acid (AA) profile of the duodenal protein was affected by the starch source. It was concluded that the metabolism of nitrogen in the forestomachs of cattle is affected by the source of starch and the ratio of forage to concentrate. There exists a relationship between both factors. The net synthesis of microbial protein in the rumen is not only the result of substrate fermentation. The passage of non-AFOM from the rumen significantly affects the energetic efficiency of microbial nitrogen synthesis and the duodenal supply of AA.
在9个试验期内，对4头成年公牛（体重550千克）进行试验，这些公牛在十二指肠近端安装了再入式套管，在饲养水平1.7时使用等能量日粮，分别以粉碎大麦、粉碎玉米或新鲜土豆作为淀粉来源。日粮中这些精料的净能部分分别占50%、25%和10%。日粮干物质的50%至80%由干草组成，约10%由甜菜粕组成。干草平均提供了87%、79%和62%的饲料粗蛋白。干物质摄入量为7.74±0.42（平均值±标准差）千克/天。瘤胃中微生物氮合成的能量效率（克氮/瘤胃中真正发酵的每千克有机物质，TFOM）平均为16.4，范围为10.6至21.4。当以大麦为淀粉来源时，日粮中无氮提取物与粗纤维的比例为1.7和2.1、以土豆为淀粉来源时为1.8、以玉米为淀粉来源时为2.1和3.3时，微生物效率达到最大值。微生物效率的变化与瘤胃中非微生物有机物质的流通速率（克/天）以及十二指肠流量速率（千克消化物/千克干物质摄入量）呈正相关。与瘤胃中碳水化合物发酵速率（百分比）和TFOM量（克/天）的关系呈负相关。瘤胃中微生物氮和非氨氮的十二指肠流量（克/天）与瘤胃中明显发酵的有机物质（AFOM）呈负相关，与非AFOM呈正相关。十二指肠蛋白质的氨基酸（AA）谱受淀粉来源的影响。得出的结论是，牛前胃中氮的代谢受淀粉来源和粗饲料与精料比例的影响。这两个因素之间存在关系。瘤胃中微生物蛋白的净合成不仅是底物发酵的结果。瘤胃中非AFOM的流通显著影响微生物氮合成的能量效率和十二指肠中AA的供应。
