AGRICULTURAL RESEARCH IN NEW HAMPSHIRE 21 



fat, may be inherited separately, and that it is impossible to predict the 

 solids-not-fat change from a change in fat per cent. 



H. C. Moore, H. A. Keener 



Studies on Bovine Mastitis 



Studies were continued on the control of mastitis by segregation and 

 by treatment of cows infected with streptococcic mastitis. Forty-one cows 

 were treated with sulphanilamide in oil during lactation; 29 (70.6 per 

 cent) of the cows and 61 (74.4 per cent) of the quarters were cured. Four 

 (80 per cent) of the five cows and eight (88.8 per cent) of the quarters 

 treated with sulphanilamide during the dry period were cured. Seven 

 cows were treated with novoxil during the dry period; seven (57.1 per 

 cent) of the cows and nine (64.2 per cent) of the quarters were cured. In 

 the group of five cows treated with tyrothricin during lactation, four cows 

 (80 per cent) and 11 quarters (84.6 per cent) were cured. 



The following results were obtained on cows treated for staphylococcal 

 mastitis- (a) None of the five cows and only four out of the 15 quarters 

 treated with sulphanilamide in oil were cured, (b) One cow out of seven 

 and only three out of 16 quarters were cured when treated with tyrothricin. 

 Twelve cows were injected with an autogenous herd staphylococcus vac- 

 cine but no improvement in the mastitis condition could be detected. 



It should be noted that the above results are based on treatment of 

 cows infected with either a mild or with a more acute or chronic type of 

 mastitis infection. As previously reported, it has been found that cows 

 with acute infection, or with long-standing chronic infections, may not re- 

 spond to treatment. When sulphanilamide in oil was used for treatment of 

 lactating cows, the best results were obtained when two injections ot from 

 50 to 100 ;;;/. were given per quarter at 24-hour intervals. The drug was al- 

 lowed to remain in the udder for a 24-hour period before milking out the 

 quarter. 



Studies were also continued on the staphylococci from udders of 

 cows. A paper is being prepared on the characteristics of these organisms 



and their toxins. _ ^ , ^ ^ 



L. W. Slanetz, F. E. Allen, T. Sicilian 



FIELD CROPS 



Rotation, Fertility, and Cultural Experiments 

 With Potatoes in Northern New Hampshire 



Much of the previous experimental work located at the Coffin farm 

 near Colebrook was continued during 1943 and is being repeated during 

 the current 1944 season. Calcium sulphate was applied to potato plots in 

 \arying quantities as a supplement to normal fertilization. There has been 

 no attempt to obtain fertilizers without calcium and sulphur. Gypsum was 

 broadcast in varying amounts and was harrowed m before planting, i he 

 resulting average yields for a two-year period were as follows : 



