ment stations, many feed manufac- 

 turers started to add cobalt to their 

 rations in 1945. Because cobalt 

 was becoming so widely used in 

 concentrate rations and mineral mix- 

 tures, studies were carried out to 

 determine the tolerance of growing 

 dairy cattle to this element. It was 

 found they could consume daily for 

 periods of many weeks well over 

 100 times the amount normally con- 

 sumed from the commercially mixed 

 dairy ration containing added co- 

 balt.' 



The next step was to develop the 

 deficiency and study it under con- 

 trolled conditions. This was done, 

 using sheep as experimental sub- 

 jects. A low-cobalt, locally-grown 

 grass hay and corn purchased on the 

 local market were fed. The animals 

 were paired on the basis of weight, 

 breed, and sex. One member of 

 each pair was given 7 milligrams of 

 supplemental cobalt twice a week. 

 During a period of 26 weeks those 

 animals which were given cobalt 

 gained approximately two and one- 

 half times as much as those which 

 were given none. The deficiency 

 symptoms were the same as for cat- 

 tle, i.e., loss of appetite followed by 

 loss in weight, emaciation, loss of 

 wool, etc. One very interesting ob- 

 servation made during this experi- 

 ment was that internal parasites 

 were very much more harmful to 

 the deficient sheep than to those re- 

 ceiving cobalt. 



In order to substantiate this ex- 

 periment and to learn more about 

 the function of cobalt in the diet of 

 the ruminant, a second experiment 

 was carried out — this has just 

 been completed. It proved conclu- 

 sively that cobalt deficiency could 

 be developed in sheep when a low- 

 cobalt ration was fed. All the 18 

 animals that were on the deficient 

 ration for a considerable period of 



time showed very marked cobalt 

 deficiency symptoms. All 10 ani- 

 mals which were given 3V2 m g- of co- 

 balt twice a week remained in per- 

 fect health. Despite the fact that 

 evidence indicates that cobalt is 

 necessary for the production of 

 some appetite-stimulating vitamin or 

 other factor by the flora of the ru- 

 men, all attempts to alleviate the 

 deficiency symptoms by means of 

 synthetic vitamins, amino acids, 

 liver extract, other minerals, etc. 

 have been unsuccessful. 



At the present time cobalt defi- 

 ciency is very rare in New Hamp- 

 shire because of the widespread 

 feeding of cobalt-containing rations, 

 cobalt-containing mineral mixtures, 

 and the direct use of cobalt salts. 

 That the cost is low is proved by 

 the fact that many farmers are pro- 

 tecting the entire herd for well un- 

 der one dollar per year. 



H. A. Keener, G. P. Percival, 

 K. S. Morrow, and J. R. Prescott 



The Infusion of 4 00,000 Units of 

 Penicillin is Very Effective in the 

 Cure of Streptococcal Mastitis. Dur- 

 ing the past year particular attention 

 has been devoted to the treatment of 

 streptococcal mastitis with penicillin 

 and penicillin and sulfamethazine 

 combined. It was found that if 

 400,000 units of penicillin were al- 

 lowed to remain in each quarter for 

 a 24-hour period without milking, 

 excellent results occurred — much 

 better than when only 12 hours were 

 allowed without milking. Of all the 

 cases tested, 89 per cent were cured 

 by this treatment. Combining 100 

 ml. of 10 per cent sodium sulfameth- 

 azine with 200,000 or with 400,000 

 units of penicillin did not prove ad- 

 vantageous as compared with peni- 

 cillin alone. 



L. W. Slanetz and F. E. Allen 



14 



