Anderson S J, Klopfenstein T J, Wilkerson V A
Dept. of Anim. Sci., University of Nebraska, Lincoln 68583.
J Anim Sci. 1988 Jan;66(1):237-42. doi: 10.2527/jas1988.661237x.
Two grazing trials utilizing individually supplemented yearling steers were conducted to study the effect of supplemental escape protein on steer performance during the active growth periods, spring and fall, of smooth brome (Bromus inermis). Graded levels (0, .11, .23 and .34 kg.head-1.d-1) of an equal-protein-basis mixture of bloodmeal and corn gluten meal were offered daily, replacing corn starch, which was used as the negative control. All steers received 582 g supplemental dry matter per day. Supplementation with escape protein improved daily performance in both spring (P less than .01) and fall (P less than .02). Analysis of pooled data from both trials indicated a linear (P less than .01) and quadratic (P less than .05) increase in steer performance with increasing level of escape protein in the diet. Analysis of grass samples collected throughout and composited over each trial demonstrated that grass protein was highly degraded in the rumen. Using a modified dacron bag technique, 12-h degradability was found to be 80 to 90% of the potentially digestible protein fraction. Rates of protein degradability were 14 and 11.7%/h. Assuming 5%/h rate of passage, escape protein was calculated to be 9.2 and 13.1% of total protein. As a result of the significant growth response observed above that of the energy-supplemented controls and the high ruminal protein degradabilities of the grass observed in the laboratory, it was concluded that growing ruminants grazing actively growing smooth brome pastures were deficient in metabolizable protein.
进行了两项利用单独补饲一岁公牛的放牧试验，以研究补充性过瘤胃蛋白对在无芒雀麦（Bromus inermis）春季和秋季活跃生长期间公牛生产性能的影响。每天提供等量蛋白质基础的血粉和玉米蛋白粉混合物的分级水平（0、0.11、0.23和0.34千克/头·天），替代用作阴性对照的玉米淀粉。所有公牛每天接受582克补充干物质。补充过瘤胃蛋白在春季（P<0.01）和秋季（P<0.02）均提高了日生产性能。对两项试验的汇总数据进行分析表明，随着日粮中过瘤胃蛋白水平的增加，公牛生产性能呈线性（P<0.01）和二次曲线（P<0.05）增加。对在每次试验期间收集并混合的草样进行分析表明，草蛋白在瘤胃中高度降解。使用改良的涤纶袋技术，发现12小时降解率为潜在可消化蛋白部分的80%至90%。蛋白降解率分别为14%/小时和11.7%/小时。假设通过率为5%/小时，计算得出过瘤胃蛋白占总蛋白的9.2%和13.1%。由于观察到的生长反应显著高于补充能量的对照组，且在实验室中观察到草的瘤胃蛋白降解率很高，因此得出结论，在积极生长的无芒雀麦草地上放牧的生长反刍动物缺乏可代谢蛋白。
