Moore J A, Poore M H, Swingle R S
Dept. of Anim. Sci., University of Arizona, Tucson 85721.
J Anim Sci. 1990 Oct;68(10):3412-20. doi: 10.2527/1990.68103412x.
Roughage sources were compared in flaked milo-based diets that contained 35% chopped alfalfa hay (AH, control diet) or with cottonseed hulls (CSH) or chopped wheat straw (WS) replacing half the AH. Latin square experiments were used to measure total tract digestion coefficients, particulate passage rates (rare earths), liquid turnover rates (Co-EDTA), and rumination time in six growing steers (Exp. 1) and in situ digestion of DM and NDF, ruminal pH and ruminal DM distribution in three mature, ruminally cannulated steers (Exp. 2). Rates of passage from Exp. 1 and rates and extents of digestion from Exp. 2 were used to calculate apparent extent of ruminal digestion (AED). In Exp. 1, total tract digestibilities of DM and NDF were lower (P less than .05) by 7 and 22%, respectively, when CSH, but not WS, were included in the diet. Digestibility of cell solubles was not different (P greater than .10) among diets. Inclusion of WS increased (P less than .10) rumination time by 36%, and CSH increased intake (P less than .10) by 17% over the control diet. In Exp. 2, there tended to be (P less than .20) increased in situ digestion of milo and AH in the WS diet. Measures of ruminal pH were similar for all diets. The AED for AH and milo DM and NDF, and the proportion of total tract NDF digestion occurring in the rumen (50, 47 and 62% for control, CSH and WS diets, respectively), were highest (P less than .05) for the WS diet. This resulted in similar total tract digestibilities for the WS and AH diets. The two low-digestibility roughages had different effects at this concentrate level; wheat straw enhanced apparent extent of ruminal digestion for NDF of other ingredients in the mixed diets, but cottonseed hulls did not.
在以碎粒高粱为基础的日粮中，对粗饲料来源进行了比较。这些日粮包含35%的切碎苜蓿干草（AH，对照日粮），或者用棉籽壳（CSH）或切碎小麦秸秆（WS）替代一半的AH。采用拉丁方试验，在6头生长中的阉牛中（试验1）测定全消化道消化系数、颗粒通过率（稀土元素）、液体周转率（钴-乙二胺四乙酸）和反刍时间，在3头装有瘤胃瘘管的成年阉牛中（试验2）测定干物质（DM）和中性洗涤纤维（NDF）的原位消化率、瘤胃pH值和瘤胃DM分布。试验1中的通过率以及试验2中的消化率和消化程度用于计算瘤胃消化的表观程度（AED）。在试验1中，当日粮中包含CSH而非WS时，DM和NDF的全消化道消化率分别降低了7%和22%（P<0.05）。日粮间细胞可溶物的消化率没有差异（P>0.10）。与对照日粮相比，添加WS使反刍时间增加了36%（P<0.10），添加CSH使采食量增加了17%（P<0.10）。在试验2中，WS日粮中高粱和AH的原位消化率有增加的趋势（P<0.20）。所有日粮的瘤胃pH值测量结果相似。WS日粮中AH和高粱DM及NDF的AED，以及全消化道NDF消化在瘤胃中发生的比例（对照、CSH和WS日粮分别为50%、47%和62%）最高（P<0.05）。这导致WS和AH日粮的全消化道消化率相似。在这种精料水平下，两种低消化率粗饲料有不同的影响；小麦秸秆提高了混合日粮中其他成分NDF的瘤胃消化表观程度，但棉籽壳没有。
