Van Straalen W M, Dooper F M, Antoniewicz A M, Kosmala I, Van Vuuren A M
Research Institute for Livestock Feeding and Nutrition (IVVO-DLO), Lelystad, The Netherlands.
J Dairy Sci. 1993 Oct;76(10):2970-81. doi: 10.3168/jds.S0022-0302(93)77636-5.
Ruminal, intestinal, and total tract digestibilities of CP in grass, grass silage, and clover were measured using the mobile nylon bag method. Total tract indigestibilities measured with this method were compared with indigestible CP predicted by in vitro, 14-d ruminal incubation, and 12-h followed by 14-d ruminal incubation methods. Indigestible CP was related to chemical composition and harvest date. Ruminal disappearance of CP from nylon bags was 58, 71, and 58% for grass, grass silage, and clover, respectively. Intestinal CP disappearance was 84, 81, and 91% of escape CP, respectively. Lower ruminal disappearance was compensated by higher intestinal disappearance, resulting in a small variation in total tract indigestible CP within forage. Total tract indigestible CP was 7, 6, and 4%, respectively. Average total tract indigestible CP measured with the mobile nylon bag method (6%) was lower than that estimated by the in vitro (13%), 14-d ruminal incubation (14%), or 12-h ruminal incubation followed by 14-d ruminal incubation (11%) methods. All methods ranked forages similarly, resulting in high correlation coefficients among methods within forage. Total tract indigestible CP of grass, grass silage, and clover was related to CP content and harvest date, DM and ADIN content, and DM and CP contents, respectively.
采用移动尼龙袋法测定了青草、青贮青草和三叶草中粗蛋白的瘤胃、肠道及全消化道消化率。将该方法测得的全消化道不可消化率与体外法、14天瘤胃培养法以及12小时后接14天瘤胃培养法预测的不可消化粗蛋白进行了比较。不可消化粗蛋白与化学成分和收获日期有关。青草、青贮青草和三叶草从尼龙袋中的瘤胃消失率分别为58%、71%和58%。肠道粗蛋白消失率分别为逃逸粗蛋白的84%、81%和91%。瘤胃消失率较低可通过较高的肠道消失率得到补偿，从而使不同饲料间全消化道不可消化粗蛋白的差异较小。全消化道不可消化粗蛋白分别为7%、6%和4%。采用移动尼龙袋法测得的平均全消化道不可消化粗蛋白（6%）低于体外法（13%）、14天瘤胃培养法（14%）或12小时瘤胃培养后接14天瘤胃培养法（11%）估算的值。所有方法对饲料的排序相似，导致不同方法在饲料内的相关系数较高。青草、青贮青草和三叶草的全消化道不可消化粗蛋白分别与粗蛋白含量和收获日期、干物质和酸性洗涤不溶性氮含量以及干物质和粗蛋白含量有关。
