MAINE AGRICULTURAL EXPERIMENT STATION. 23 



4. THE RELATION OF THE TIME OF SERVICE TO THE SEX 

 RATIO IN CATTLE. 



One of the primary purposes for which the cooperative 

 cattle breeding record plan discussed in the preceding sections 

 was undertaken was to get comprehensive statistics to show 

 whether any definite effect on the proportion of male and 

 female calves born could be observed when service occurred at 

 different times in the heat period. Work done at the Station 

 some years ago suggested that when service occurred very 

 early in heat there was likely to be born a larger proportion of 

 heifer calves, and when service occurred very late in heat 

 there was likely to be born a larger proportion of bull calves. 

 With the hope of getting a very much larger amount of more 

 precise data on this point, and demonstrating whether the sug- 

 gestion of the earlier results was correct or not, the cattle 

 breeding record plan was inaugurated. 



A considerable mass of material on this point has accumu- 

 lated, but it is thought desirable to wait until another year's 

 records are in hand before reporting further in regard to the 

 matter. 



5. CYSTIC DEGENERATION OF THE OVARIES. 



During the past year there has been published the results of 

 the study" of an interesting case of a fairly common cause of 

 sterility in cows. A pure-bred registered Ayrshire cow, named 

 Dorothy of Orono (23010), belonging to the University of 

 Maine, produced three calves, on dates an follows : Septem- 

 ber 17, 1909, September 10, 1910, February 24, 1912. When 3 

 years and 327 days old Dorothy of Orono was started on an 

 official milk test of one year, which she completed with a 

 record of 11463 lbs. of milk, carrying 417.71 lbs. of butter fat. 

 I'or this record she was entered as No. 426 in the Ayrshire 

 Advanced Registry. Her complete lactation record is shown 

 in Table 10. 



"Pearl, R. and Surface, F. M. Sex Studies. VII. On the Assump- 

 tion of Male Secondary Characters by a Cow with Cystic Degeneration 

 of the Ovaries. Me. Agr. Expt. Stat. Ann. Rept., 1915, pp. 65-80. 



