Coe M L, Nagaraja T G, Sun Y D, Wallace N, Towne E G, Kemp K E, Hutcheson J P
Department of Animal Sciences, Kansas State University, Manhattan 66506, USA.
J Anim Sci. 1999 Aug;77(8):2259-68. doi: 10.2527/1999.7782259x.
The objective of Exp. 1 was to compare the effects of virginiamycin (VM; 0, 175, or 250 mg x animal(-1) x d(-1)) and monensin/tylosin (MT; 250/ 90 mg x animal(-1) x d(-1)) on ruminal fermentation products and microbial populations in cattle during adaptation to an all-concentrate diet. Four ruminally cannulated, Holstein steers were used in a 4x4 Williams square design with 21-d periods. Steers were stepped up to an all-concentrate diet fed at 2.5% of BW once daily. Ruminal pH, protozoal counts, and NH3-N and VFA concentrations generally were unaffected by VM or MT. Mean counts of Lactobacillus and Streptococcus bovis were lower (P<.05) for VM-treated compared with control or MT-treated steers. Both VM and MT prevented the increase in Fusobacterium necrophorum counts associated with increasing intake of the high-concentrate diet observed in the control. The objective of Exp. 2 was to compare the effects of VM and MT on ruminal pH, L(+) lactate and VFA concentrations, and F. necrophorum numbers during carbohydrate overload. Six ruminally cannulated Holstein steers were assigned randomly to either the control, VM (175 mg/d), or MT (250 + 90 mg/d) treatments. Acidosis was induced with intraruminal administration of a slurry of ground corn and corn starch. The VM and MT premixes were added directly to the slurry before administration. Carbohydrate challenge induced acute ruminal acidosis (pH was 4.36 and L (+) lactate was 19.4 mM) in controls by 36 h. Compared with the controls, steers receiving VM or MT had higher (P<.05) ruminal pH, and the VM group had a lower (P<.05) L (+) lactate concentration. Fusobacterium necrophorum numbers initially increased in VM- and MT-administered steers. In the control steers, F. necrophorum was undetectable by 36 h. Virginiamycin seemed to control the growth of ruminal lactic acid-producing bacteria and, therefore, has the potential to moderate ruminal fermentation in situations that could lead to rapid production of lactic acid.
试验1的目的是比较维吉尼亚霉素（VM；0、175或250毫克/头/天）和莫能菌素/泰乐菌素（MT；250/90毫克/头/天）对适应全精料日粮的奶牛瘤胃发酵产物和微生物种群的影响。选用4头安装了瘤胃瘘管的荷斯坦公牛，采用4×4威廉姆斯方设计，每期21天。公牛逐渐增加到按体重的2.5%每日投喂一次全精料日粮。瘤胃pH值、原虫数量以及氨氮和挥发性脂肪酸（VFA）浓度一般不受VM或MT的影响。与对照或MT处理的公牛相比，VM处理的乳酸杆菌和牛链球菌平均数量较低（P<0.05）。VM和MT均能防止对照中观察到的与高精料日粮摄入量增加相关的坏死梭杆菌数量增加。试验2的目的是比较VM和MT对碳水化合物超载期间瘤胃pH值、L(+)乳酸和VFA浓度以及坏死梭杆菌数量的影响。将6头安装了瘤胃瘘管的荷斯坦公牛随机分配到对照、VM（175毫克/天）或MT（250 + 90毫克/天）处理组。通过瘤胃内注射磨碎的玉米和玉米淀粉浆液诱导酸中毒。在注射前将VM和MT预混物直接添加到浆液中。到36小时时，碳水化合物刺激在对照组中诱发了急性瘤胃酸中毒（pH值为4.36，L(+)乳酸为19.4毫摩尔）。与对照组相比，接受VM或MT的公牛瘤胃pH值较高（P<0.05），VM组的L(+)乳酸浓度较低（P<0.05）。在注射VM和MT的公牛中，坏死梭杆菌数量最初增加。在对照公牛中，到36小时时未检测到坏死梭杆菌。维吉尼亚霉素似乎能控制瘤胃中产乳酸细菌的生长，因此，在可能导致乳酸快速产生的情况下，有缓和瘤胃发酵的潜力。
