230 AGRICULTURE OF MAINE. 



with the writer of this report. It is expected that the collection 

 of breeding records will be continued for at least one more 

 year. 



It appears desirable at this time to present brief statements 

 regarding certain of the results which have been reached from 

 the study of these records. This is done in Section IV of this 

 report. Detailed publication will follow in due tim.e in another 

 place. 



IV. Physiology of Cattle Breeding. 



Here we shall consider certain topics based in part upon the 

 cooperative breeding records, and in part upon other studies. 



I. THE normal duration OF HEAT (oESTRUm) IN CATTLE. 



The cooperative breeding records furnish extensive data 

 bearing upon this point. Table 6 shows for various breeds the 

 number of hours which elapsed between (a) the time when the 

 breeder observed that the cow was in heat and (b) the time 

 when she was served by the bull. All of the services recorded 

 in this table were successful, i. e., the cow became pregnant as 

 a result of the recorded service, and either carried the calf 

 to term, or aborted at some time before term. 



