June 1941] Agricultural Research in New Hampshire 27 



used in makin°r the tests. In the table below some of the results of 

 the experiment have been recorded. It will be noted that the energy- 

 expended increased rapidly as the load increased. 



Energy expended 



(Purnett Fund) 



Sheep Breeding (E. G. Ritzman and A. D. Littlehale) 



The research on applied genetics with sheep is now in its final 

 stage of progress. During the last four years a gradual shift has been 

 made to standardize the flock on a Suffolk tvpe basis, but possessing 

 four functional nioples and also a high twin-bearing tendency. That 

 the yield of milk from four-nipple ewes has been increased is demon- 

 strated in part by the rate of growth of lambs from these ewes. 

 Daily grains of twins from four-nipple ewes exceeded the gains of 

 twins from two-nipple ewes by 47 per cent during the first 42 davs 

 of growth, while the corresponding figure for single lambs was 36 

 per cent. 



A factor theory illustrating the probable method of inheritance 

 of this trait was proposed. This appears to check closely enough 

 with the actual results obtained by breeding tests to offer a prospect 

 for breed improvement in this particular functional trait on the basis 

 of genetic principles. 



In terms of practical results in the development of the twinning 

 tendency, some progress is demonstrated by a comparison of the 

 lamb production in the original foundation stock, which was 135 

 per cent, with that of the 1940 flock^ which (even including first lamb 

 ewes) was 161 per cent, and 185 per cent for a selected group of ewes. 



(Adams Fund) 



Studies on Bovine Mastitis (L. W. Slanetz) 



Studies on the classification of mastitis streptococci and staphy- 

 lococci and on the effectiveness of segregation for the control of mas- 

 titis were continued. Particular attention was given to the toxins 

 produced by staphylococci associated with mastitis infection, and to 

 the isolation and determination of characteristics of bacteriophages 

 used against these organisms. 



A highly buffered glucose beef-infusion agar medium was found 

 to be essential for the production of potent staphylococcus toxins. 

 The use of 1.0 per cent agar, incubation in an atmosphere containing 

 20 to 30 per cent carbon dioxide and incubation of 37°C for 48 hours 



