Ba. Cummings et al., RUMINAL MICROBIAL ALTERATIONS ASSOCIATED WITH SULFIDE GENERATION IN STEERS WITH DIETARY SULFATE-INDUCED POLIOENCEPHALOMALACIA, American journal of veterinary research, 56(10), 1995, pp. 1390-1395
Holstein steers were fed carbohydrate-rich, short-fiber basal diets wi
th and without added sodium sulfate. Steers fed the high-sulfate diet
developed the CNS disorder polioencephalomalacia (PEM). The onset of s
igns 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 to determi
ne the effect of dietary sulfate on sulfate-reducing bacterial numbers
. Media used included a general type for total counts and sulfate-cont
aining media with and without cysteine to assess sulfate-reducing bact
eria. Changes in total and sulfate-reducing bacterial numbers attribut
able to dietary sulfate content were not observed. The capacity to gen
erate hydrogen sulfide from sulfate in fresh rumen fluid in vitro was
substantially increased only after steers had been fed the high-sulfat
e diet for 10 to 12 days, which coincided with the onset of signs of P
EM. The low capacity for hydrogen sulfide production of rumen fluid ta
ken at earlier times in the feeding period suggests that numen microor
ganisms must adapt to higher dietary sulfate content before they are c
apable of generating potentially toxic concentrations of sulfide.