30 Station Bulletin 372 



the digestive tract. Daily urinary and fecal excretion of thiamine and ribo- 

 flavin were determined for two Holstein heifers under normal conditions and 

 when sulfathaladine was fed to alter the flora of the digestive tract. Some 

 decrease in the excretion of thiamine and riboflavin was observed during the 

 feeding of the sulfathalidine. Work to date indicates the possibility of using 

 urinary and fecal analyses for measuring vitamin synthesis in the digestive 

 tract. 



K. S. Morrow, H. A. Keener, A. E. Teeri 



Studies on Bovine Mastitis 



Studies were continued on the treatment of bovine mastitis with peni- 

 cillin. A special effort was made to determine the efficacy of one infusion of 

 400,000 units of penicillin for the treatment of streptococcal mastitis. The 

 penicillin was administered via the teat canal in 100 ml. of sterile water. At- 

 tention was also given to the use of sulfamethazine for the treatment of strep- 

 tococcal mastitis. 



One infusion of 400,000 units of penicillin was as effective as the ad- 

 ministration of several smaller doses of penicillin for the treatment of strep- 

 tococcal mastitis. In a group of 21 cows with the advanced, chronic or the 

 acute type of streptococcal mastitis, 85.7 per cent of the cows and 90 per 

 cent of the infected quarters were cured. These types of mastitis are most 

 difficult to cure. Some evidence was obtained that practically 100 per cent 

 cures may be produced if the quarters are not milked until 24 hours after 

 treatment. When used in combination with penicillin, sulfamethazine did 

 not appear to appreciably increase the percentage of cures. The major por- 

 tion of this work is reported in a paper entitled "Further Studies on the 

 Treatment of Bovine Mastitis with Penicillin" and is now in press for the 

 Journal of American Veterinary Medical Association. 



L. W. Slanetz, F. E. Allen 



ENTOMOLOGY 



Penetration and Toxicity of Contact Insecticides 



The study of the effect of various compounds on the toxicity of insecti- 

 cides in present use was begun in the fall of 1946. In seeking to improve 

 the performance of pyrethrum, exploratory tests were made with 44 chemicals 

 in combination with pyrethrum. Chemicals examined included various al- 

 cohols, cellosolves, phthalates, vegetable oils, and salicylates. These materials 

 were prepared in the form of household sprays and were applied on the com- 

 mon housefly. 



Of the 44 chemicals used, 10 showed synergistic action, when used in 

 combination with a pyrethrum fly spray. Eleven compounds showed no 

 eftect or exhibited a slight antagonistic effect, while the rest showed some 

 tendency to increase the toxicity of the spray. 



The salicylates which showed marked toxicity in initial tests were ex- 

 amined in greater detail. Various combinations of the sprays and the syner- 

 gists were tested to determine the best possible concentrations for use in a fly 

 spray. 



