Cobalt and thiabendazole live-weight responses in grazing sheep, and their relation to the urinary excretion of methylmalonic acid

Abstract In an experiment during which groups of grazing sheep became affected, first by a naturally acquired infestation of internal parasites, and, later, by cobalt deficiency disease, the effects of both diseases considered together, on death rate and on weight gain deficit, were materially greater than those of either disease considered separately. Results for one lot of faecal samples showed that, for sheep not given thiabendazole, the parasite egg count for a group not given cobalt was significantly higher than that for a cobalt-treated group. For sheep not given cobalt, a group that did not receive thiabendazole showed a lower vitamin B12 status than did an anthelmintictreated group. However, differences did not attain statistical significance, possibly because, under the experimental conditions that eventually obtained, only one of the two diseases (cobalt deficiency disease or parasitism) tended to be active at the times of sampling. Irrespective of whether or not thiabendazole was given, cobaltd...