Study of the influence of high levels of sulfate on the rumen microbial synthesis of thiamin in a semi-continuous fermentor (Rusitec)

摘要

The cerebrocortical necrosis (CCN) of ruminants is a nervous syndrome usually linked to thiamin metabolism. Recently, cases of CCN have also been described in animals receiving high dietary sulfate levels (Rousseaux et al, 1991, J Vet Med, A38, 229-239), The Rusitec system was used in the present experiment to study the effect of high sulfate levels on the rumen microbial synthesis of thiamin. Four one litter vessels received daily 14 g of a thiamin free purified substrate composed of pure cellulose(3.5 g), pectin (2 g), xylan (1.5 g) and starch (7 g). The substrate was enclosed in a nylon bag remaining 48 h in the fermentors. All nitrogen (N) was provided by 0.94 g/d of urea.