摘要
Objective To determine the prevalence of subacute rumen acidosis (SARA) in beef cattle grazing lush pasture and the effect of monensin on reducing SARA and improving animal performance.
Design Commercial Angus and Murray Grey steers received a monensin slow-release capsule (n = 19) or remained untreated (n = 19). Cattle grazed an oats crop or tetraploid ryegrass pasture for a total of 91 days. Rumen fluid pH, volatile fatty acids (VFA) and lactic acid concentrations and body weight data were collected prior to treatment and again 28, 56 and 91 days after treatment. Changes in measures over time were analysed using mixed model repeated measures analysis. Differences in average daily gain between treatment groups were determined.
Results The prevalence of SARA was low during the study, with only one animal satisfying criteria for SARA at one time point. Cattle treated with monensin capsules were 11.9 kg heavier at the completion of the study compared with untreated controls (414.5 ± 3.88 kg vs 402.6 ± 4.03 kg, P = 0.04). Rumen VFA and L- and D-lactate levels did not differ between cattle treated with monensin and untreated cattle. However, the ratio of propionate to acetate plus two times butyrate was higher (P < 0.001) when cattle were treated with monensin.
Conclusions Subacute rumen acidosis was not consistently detected under the conditions of the study. The higher body weight of cattle treated with monensin may have been due to improved energy utilisation of the pasture, indicated by increased propionate proportions in the rumen, rather than prevention of SARA.
摘要译文
目的：确定亚急性瘤胃酸中毒（SARA）肉牛放牧草场茂盛和莫能菌素对降低SARA和提高动物生产性能的影响的患病率。设计商业安格斯和穆雷灰色公牛获得了莫能菌素缓释胶囊（N \x3d 19）或保持未处理（N \x3d 19）。牛吃草的燕麦作物或四倍体黑麦草牧场，共91天。瘤胃液pH值，挥发性脂肪酸（VFA）和乳酸浓度和体重的数据收集处理之前和再治疗后28，56和91天。使用混合模型重复测量分析随时间的变化措施进行了分析。在治疗组之间平均日增重差异决定的。结果SARA的患病率较低的研究期间，与在一个时间点只有一个动物满足标准SARA。与莫能菌素胶囊治疗牛人11。9千克较重在完成研究与未经处理的对照组（414.5±3.88千克VS 402.6±4.03公斤，P \x3d 0.04）。瘤胃VFA和L-和D-乳酸水平与莫能菌素和未经处理的牛处理牛之间没有差异。然而，丙酸之比为乙酸盐加上两倍丁酸为高（P0.001），当牛人与莫能菌素治疗。\r
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未研究的条件下，始终检测结论亚急性瘤胃酸中毒。较高的体重牛与莫能菌素治疗可能是由于牧场的提高能源利用率，通过丙酸比例在瘤胃增加表明，而不是预防SARA的。
EL Packer[1]; EH Clayton[2,3] and PMV Cusack[4];. Rumen fermentation and liveweight gain in beef cattle treated with monensin and grazing lush forage[J]. Australian Veterinary Journal, 2011,89(9): 338-345