Guan H, Wittenberg K M, Ominski K H, Krause D O
Department of Animal Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
J Anim Sci. 2006 Jul;84(7):1896-906. doi: 10.2527/jas.2005-652.
Use of ionophores in cattle diets has been proposed as a strategy for mitigation of enteric CH4 emissions. Short- and long-term effects of feeding a single ionophore (monensin) or rotation of 2 ionophores (monensin and lasalocid) on enteric CH4 emissions were evaluated in 36 Angus yearling steers (328 +/- 24.9 kg of BW) over a 16-wk period. Steers were randomly assigned to 6 dietary treatments of 6 steers each. The 6 diets were low-concentrate without ionophore supplementation, low-concentrate with monensin supplementation, low-concentrate with a 2-wk rotation of monensin and lasalocid supplementation, high-concentrate without ionophore supplementation, high-concentrate with monensin supplementation, and high-concentrate with a 2-wk rotation of monensin and lasalocid supplementation. Daily enteric CH4 emissions, as measured using the SF(6) tracer gas technique, ranged from 54.7 to 369.3 L/steer daily. Supplementing ionophores decreased (P < 0.05) enteric CH4 emissions, expressed as liters per kilogram of DMI or percentage of GE intake, by 30% for the first 2 wk and by 27% for the first 4 wk, for cattle receiving the high-concentrate and low-concentrate diets, respectively. Cattle fed a rotation of ionophores did not (P > 0.05) exhibit a greater decrease and did not (P > 0.05) have a longer period of depressed enteric CH4 emissions compared with cattle receiving monensin only. Ionophore supplementation did not (P > 0.05) alter total ruminal fluid VFA concentration; however, the acetate:propionate ratio and ammonia-N concentration in ruminal fluid were decreased (P < 0.001) from the time that ionophores were introduced to the time they were removed from the diets. Both monensin and the rotation of monensin and lasalocid decreased (P < 0.001) total ciliate protozoal populations by 82.5% in the first 2 wk and by 76.8% in the first 4 wk during which they were supplemented in the high-concentrate and low-concentrate diets, respectively. Original ciliate protozoal populations were restored by the fourth and sixth week of supplementation when cattle were fed the high- or low-concentrate diets, respectively. No significant change was observed thereafter. These data suggest that the effects of ionophores on enteric CH(4) production are related to ciliate protozoal populations and that ciliate protozoal populations can adapt to the ionophores present in either low- or high-concentrate diets. Rotation of monensin and lasalocid did not (P > 0.05) prevent ciliate protozoal adaptation to ionophores.
在牛的日粮中使用离子载体已被提议作为减少肠道甲烷排放的一种策略。在16周的时间里，对36头安格斯一岁公牛（体重328±24.9千克）评估了饲喂单一离子载体（莫能菌素）或两种离子载体轮换（莫能菌素和拉沙洛西）对肠道甲烷排放的短期和长期影响。公牛被随机分配到6种日粮处理组，每组6头。这6种日粮分别是不添加离子载体的低精料日粮、添加莫能菌素的低精料日粮、莫能菌素和拉沙洛西轮换添加2周的低精料日粮、不添加离子载体的高精料日粮、添加莫能菌素的高精料日粮以及莫能菌素和拉沙洛西轮换添加2周的高精料日粮。使用SF(6)示踪气体技术测量，每日肠道甲烷排放量为每头公牛每天54.7至369.3升。对于接受高精料和低精料日粮的牛，添加离子载体分别在前2周和前4周使以每千克干物质采食量升数或总能摄入量百分比表示的肠道甲烷排放量降低（P<0.05）30%和27%。与仅接受莫能菌素的牛相比，饲喂离子载体轮换的牛没有（P>0.05）表现出更大的降低，也没有（P>0.05）出现肠道甲烷排放抑制期更长的情况。添加离子载体没有（P>0.05）改变瘤胃液挥发性脂肪酸的总浓度；然而，从将离子载体引入日粮到从日粮中去除，瘤胃液中乙酸:丙酸比例和氨氮浓度降低（P<0.001）。在高精料和低精料日粮中添加莫能菌素以及莫能菌素和拉沙洛西轮换添加的前2周和前4周，莫能菌素和莫能菌素与拉沙洛西轮换添加分别使总纤毛虫原生动物数量降低（P<0.001）82.5%和76.8%。当牛分别饲喂高精料或低精料日粮时，在添加的第4周和第6周原生纤毛虫数量恢复到原来水平。此后未观察到显著变化。这些数据表明，离子载体对肠道甲烷产生的影响与纤毛虫原生动物数量有关，并且纤毛虫原生动物数量可以适应低精料或高精料日粮中的离子载体。莫能菌素和拉沙洛西轮换添加没有（P>0.05）阻止纤毛虫原生动物对离子载体的适应。
