Cummings B A, Gould D H, Caldwell D R, Hamar D W
Department of Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins 80523, USA.
Am J Vet Res. 1995 Oct;56(10):1390-5.
Holstein steers were fed carbohydrate-rich, short-fiber basal diets with and without added sodium sulfate. Steers fed the high-sulfate diet developed the CNS disorder polioencephalomalacia (PEM). The onset of signs of PEM was associated with increased sulfide concentration in the rumen fluid. Over the course of the disease, anaerobic rumen bacteria were enumerated in roll tubes by use of the Hungate method Lo determine the effect of dietary sulfate on sulfate-reducing bacterial numbers. Media used included a general type for total counts and sulfate containing media with and without cysteine to assess sulfate-reducing bacteria. Changes in total and sulfate reducing bacterial numbers attributable to dietary sulfate content were not observed. The capacity to generate hydrogen sulfide from sulfate in fresh rumen fluid in vitro was substantially increased only after steers had been fed the high sulfate diet for 10 to 12 days, which coincided with the onset of signs of PEM. The low capacity for hydrogen sulfide production of rumen fluid taken at earlier times in the feeding period suggests that rumen microorganisms must adapt to higher dietary sulfate content before they are capable of generating potentially toxic concentrations of sulfide.
给荷斯坦公牛饲喂富含碳水化合物、纤维短的基础日粮，部分日粮添加硫酸钠，部分不添加。饲喂高硫酸盐日粮的公牛患上了中枢神经系统疾病脑灰质软化症（PEM）。PEM症状的出现与瘤胃液中硫化物浓度升高有关。在疾病过程中，使用亨盖特方法在滚管中对厌氧瘤胃细菌进行计数，以确定日粮硫酸盐对硫酸盐还原细菌数量的影响。使用的培养基包括用于总计数的通用类型以及含硫酸盐的培养基（添加和不添加半胱氨酸），以评估硫酸盐还原细菌。未观察到日粮硫酸盐含量导致的总细菌数和硫酸盐还原细菌数的变化。仅在公牛饲喂高硫酸盐日粮10至12天后，新鲜瘤胃液体外从硫酸盐产生硫化氢的能力才大幅增加，这与PEM症状的出现时间一致。在饲喂期较早时间采集的瘤胃液产生硫化氢的能力较低，这表明瘤胃微生物在能够产生潜在有毒浓度的硫化物之前，必须适应更高的日粮硫酸盐含量。
