Siddons R C, Paradine J, Gale D L, Evans R T
Br J Nutr. 1985 Sep;54(2):545-61. doi: 10.1079/bjn19850139.
Estimates of degradability of nitrogen in the sheep rumen for a basal hay diet and for soya-bean meal (SBM), groundnut meal (GNM) and fish meal (FM), when given together with the hay, were determined from measurements of duodenal N flow, ammonia kinetics and rumen N disappearance from polyester bags and rumen outflow rate. The ability of various in vitro procedures to predict in vivo N degradability was also examined. Four sheep were given a basal hay diet (800 g dry matter (DM) and 19 g N/d) either alone or supplemented with isonitrogenous amounts (15 g N/d) of SBM, GNM or FM. Duodenal non-ammonia-N flow (g/d) was increased more by FM (8.0) than by GNM (5.9) and SBM (5.8), whilst microbial N flow (g/d) was increased more by SBM (3.9) than by GNM (2.3) and FM (1.6). N degradability values calculated from these results were 0.88, 0.76 and 0.57 for the SBM, GNM and FM respectively. The corresponding value for hay was calculated to be 0.76. The irreversible loss of ammonia in the forestomachs (g N/d) was increased more by SBM (11.9) than by GNM (7.2) and FM (5.8), whilst ammonia outflow from the rumen (g N/d) was increased to a similar extent by all supplements (1.1, 0.9 and 0.8 respectively), as was the amount of microbial N (g/d) synthesized from sources other than rumen ammonia (1.8, 2.0 and 1.9 respectively). N degradability values calculated from these results were 0.84, 0.54 and 0.45 for the SBM, GNM and FM respectively. The fractional rate of N disappearance (/h) when the feedstuffs were incubated in polyester bags in the rumen of sheep receiving the basal hay diet (800 g DM/d) was the highest for SBM (0.145) and lowest for FM (0.037), with the hay (0.082) and GNM (0.071) intermediate, whilst the fractional outflow rates from the rumen (/h) of the three supplements were similar (0.034, 0.038 and 0.030 for SBM, GNM and FM respectively). N degradability values calculated from these results were 0.82, 0.67 and 0.60 for the SBM, GNM and FM respectively; the value for the hay was 0.73. Of a number of in vitro procedures tested, only N solubility in sodium hydroxide and ammonia or total non-protein-N (NPN) production during incubation with rumen fluid in the absence of hydrazine sulphate ranked the supplements, although not the hay, in the same order as in the vivo degradability procedures.(ABSTRACT TRUNCATED AT 400 WORDS)
通过测量十二指肠氮流量、氨动力学以及聚酯袋中瘤胃氮消失量和瘤胃流出率，测定了以基础干草日粮以及与干草一起投喂时豆粕（SBM）、花生粕（GNM）和鱼粉（FM）在绵羊瘤胃中的氮降解率。还考察了各种体外方法预测体内氮降解性的能力。给四只绵羊分别单独饲喂基础干草日粮（800克干物质（DM）和19克氮/天），或补充等氮量（15克氮/天）的SBM、GNM或FM。FM使十二指肠非氨氮流量（克/天）增加得更多（8.0），高于GNM（5.9）和SBM（5.8），而SBM使微生物氮流量（克/天）增加得更多（3.9），高于GNM（2.3）和FM（1.6）。根据这些结果计算出的SBM、GNM和FM的氮降解率值分别为0.88、0.76和0.57。计算得出干草的相应值为0.76。SBM使前胃中氨的不可逆损失（克氮/天）增加得更多（11.9），高于GNM（7.2）和FM（5.8），而所有补充剂使瘤胃氨流出量（克氮/天）增加到相似程度（分别为1.1、0.9和0.8），瘤胃氨以外来源合成的微生物氮量（克/天）也是如此（分别为1.8、2.0和1.9）。根据这些结果计算出的SBM、GNM和FM的氮降解率值分别为0.84、0.54和0.45。当在接受基础干草日粮（800克DM/天）的绵羊瘤胃中，将饲料在聚酯袋中孵育时，SBM的氮消失分数速率（/小时）最高（0.145），FM最低（0.037），干草（0.082）和GNM（0.071）居中，而三种补充剂从瘤胃的分数流出率（/小时）相似（SBM、GNM和FM分别为0.034、0.038和0.030）。根据这些结果计算出的SBM、GNM和FM的氮降解率值分别为0.82、0.67和0.60；干草的值为0.73。在测试的多种体外方法中，只有氢氧化钠中氮的溶解度以及在不存在硫酸肼的情况下与瘤胃液孵育期间氨或总非蛋白氮（NPN）的产生，能按照与体内降解性方法相同的顺序对补充剂进行排序，不过干草除外。（摘要截断于400字）
