EFFECT OF COBALT DEPLETION ON GROWTH AND COBALT RETENTION IN ORGANS AND TISSUES OF THE RAT

In an experiment over a period of 49 days with 32 male rats initially weighing 32 g, growth rates and retention of cobalt in different organ s and tissues as well as in the whole carcass were evaluated. For this purpose, a cobalt depleted diet containing 5,9 ppb cobalt was offered which was supplemented with 0, 10, 50, 250 and 1250 ppb cobalt. From day 20 on, growth was significant higher with 1250 ppb cobalt than wit h 10 ppb cobalt, while in comparison with the other treatment groups n o difference could be observed. However, the animals without any cobal t supplementation showed even a more favourable growth pattern as the animals with 10 ppb cobalt from day 20 on. Feed intake behaved similar as the growth rates but differences between 10 ppb and 1250 ppb cobal t supplementation, respectively, were significant to all other treatme nt groups. Besides the testes, no significant differences in the organ weights between the treatment groups occurred. Increasing the oral co balt supply resulted in a higher cobalt content of all organs and tiss ues, with most of the cobalt being retained in the residual carcass in all treatment groups. The highest cobalt content of all organs was fo und in the liver. With the exception of one value there was no differe nce for all organs and tissues between the animals without cobalt supp lementation and with 10 ppb cobalt. Retention in the whole carcass exp ressed as percentage of the intake decreased with increasing cobalt su pply. This decrease was particularly obvious between the group without cobalt supplementation and the 10 ppb cobalt group. This reaction ind icates that cobalt metabolism also might be regulated at a low oral su pply.