Jones A L, Goetsch A L, Stokes S R
University of Arkansas, Fayetteville 72701.
Arch Tierernahr. 1987 Jul-Aug;37(7-8):701-11. doi: 10.1080/17450398709425383.
Five crossbred beef cows (Hereford x Angus, 428 kg), cannulated in the rumen and duodenum, were used in a Latin square experiment to determine the effects of dietary proportions of fescue (F) and bermudagrass (B) hays (0:1, .25: .75, .5:.5, .75: .25 and 1:0) on digestive function. Feed intake was 85% of ad libitum intake of F alone (1.04% of body weight). Fescue contained 1.19% nitrogen (N), 74.8% neutral detergent fibre (NDF) and 6.3% acid detergent lignin (ADL), and B contained 1.99% N, 84.5% NDF and 6.1% ADL. Ruminal ammonia-N decreased and four- and five-carbon fatty acid concentrations increased linearly (P less than .05) with increasing F. Mean particle size of duodenal digesta was not affected by F level, but specific gravity of duodenal particles changed quadratically (P less than .05) as F rose, being greatest with 25 and 50% F. Ruminal fluid volume was constant, but dilution rate increased linearly (P less than .05) as F increased. Passage rate of B was faster than that of F in mixed diets. Organic matter (OM) flow and digestibilities, true ruminal N disappearance and microbial efficiency were not affected (P greater than .10) by F. True ruminal N disappearance and microbial efficiency were not affected (P greater than .10) by F. True ruminal N disappearance ranged from 73 to 78%, and microbial growth efficiency was between 18 and 22 g microbial N/kg OM fermented. Ruminal digestibilities of NDF, acid detergent fibre (ADF), cellulose and hemicellulose decreased linearly (P less than .05) as F increased, being 68.2, 64.9, 65.6, 61.2 and 61.6% for NDF, 58.9, 54.7, 56.2, 53.3 and 53.2% for ADF, 64.7, 61.3, 62.1, 59.0 and 59.1% for cellulose, and 76.1, 74.4, 75.4, 70.1 and 72.2% for hemicellulose for 0, 25, 50, 75 and 100% F, respectively. Digestive function in beef cows fed mixed F-B diets at a low level of intake related directly to dietary forage proportions and digestive characteristics when forages were fed alone.
选用5头瘤胃和十二指肠插管的杂交肉牛（赫里福德×安格斯，体重428千克），采用拉丁方试验，以确定羊茅（F）和百慕大草（B）干草的日粮比例（0:1、0.25:0.75、0.5:0.5、0.75:0.25和1:0）对消化功能的影响。采食量为仅自由采食羊茅时采食量的85%（占体重的1.04%）。羊茅含1.19%氮（N）、74.8%中性洗涤纤维（NDF）和6.3%酸性洗涤木质素（ADL），百慕大草含1.99% N、84.5% NDF和6.1% ADL。随着羊茅比例增加，瘤胃氨氮含量降低，四碳和五碳脂肪酸浓度呈线性增加（P<0.05）。十二指肠食糜的平均粒径不受羊茅水平影响，但随着羊茅比例升高，十二指肠颗粒的比重呈二次曲线变化（P<0.05），在羊茅比例为25%和50%时最大。瘤胃液体积恒定，但随着羊茅比例增加，稀释率呈线性增加（P<0.05）。在混合日粮中，百慕大草的通过速率比羊茅快。羊茅比例对有机物质（OM）流量和消化率、瘤胃真N消失量和微生物效率无影响（P>0.10）。瘤胃真N消失量和微生物效率不受羊茅比例影响（P>0.10）。瘤胃真N消失率在73%至78%之间，微生物生长效率为每发酵1千克OM产生18至22克微生物N。随着羊茅比例增加，瘤胃中NDF、酸性洗涤纤维（ADF）、纤维素和半纤维素的消化率呈线性下降（P<0.05），对于0%、25%、50%、75%和100%的羊茅比例，NDF的消化率分别为68.2%、64.9%、65.6%、61.2%和61.6%，ADF的消化率分别为58.9%、54.7%、56.2%、53.3%和53.2%，纤维素的消化率分别为64.7%、61.3%、62.1%、59.0%和59.1%，半纤维素的消化率分别为76.1%、74.4%、75.4%、70.1%和72.2%。低采食量下采食羊茅 - 百慕大草混合日粮的肉牛消化功能与单独饲喂牧草时的日粮草料比例和消化特性直接相关。
