The results of this study showed that there was some variation in the 

 tolerance level of different animals. When a slight excess of cobalt was con- 

 sumed, there was an increase in hemoglobin and packed red-cell volume of 

 the blood. When a greater excess was consumed there was a loss of appetite, 

 a decrease in water consumption, a roughening of the. hair coat, an unsteadi- 

 ness when standing as well as an increase in hemoglobin and packed red-ceJl 

 volume. High levels of cobalt feeding increased the cobalt content of kidney 

 and liver tissues to several times that of similar animals which did not re- 

 reive cobalt, but in light of the amounts fed and the duration of the feeding, 

 these accumulations were considered to be small. Growing dairy animals 

 were found to be able to consume approximately 50 mg. of cobalt per 100 

 lbs. body weight per day from cobalt sulfate for many weeks without definite 

 harmful effects. It was concluded that over 100 times the amount of cobalt 

 fed in the ordinary cobalt-supplemented, manufactured feeds can be con- 

 sumed by growing dairy cattle without harmful effects. 



The Development of Cobalt Deficiency under Controlled Conditions 



After getting a response from feeding cobalt to deficient animals out 

 in the state, the next step was to try to develop cobalt deficiency under con- 

 trolled conditions. This was undertaken in an experiment using sheep as 

 experimental subjects. Sheep are susceptible to cobalt deficiency because 

 they have the same type of digestive tract as the cow and the goat. Their 

 relatively small size permits the use of a considerable number of them at a 

 relatively low cost. This experiment was started in January. 1946. and con- 

 tinued for a period of 27 weeks. 



This experiment was started with 10 pairs of yearling lambs. The. mem- 

 bers of each pair were similar with respect to breed, sex. size, and origin. 

 One member of each pair was given 7 mg. of cobalt twice per week as a 

 drench, the other received none. Corn meal was fed as the sole concentrate. 

 The roughage fed was a low-cobalt grass hav from a farm in southeastern 



The difference in the size of these sheared sheep is striking. The one at the left was fed 

 supplemental cobalt: the one at the right received none. 



