PRACTICAL PROBLEMS 



the calves are males and one half females, and that all descendants 

 are prolific in the same proportion as the originals. 



NUMBER OF LIVING AND PRODUCING FEMALES AT THE END OF 



VARIOUS GENERATIONS, FROM Cows OF DIFFERENT 



DEGREES OF FERTILITY 



It is easy to see that no matter what the individual excellence 

 of cow No. i and her descendants, they could never build up a 

 herd. Their rate of reproduction is so low as only to keep good 

 the original number. Careful search will discover a surprising 

 number of females of this class in the herds of otherwise suc- 

 cessful stockmen, useless from any standpoint except the 

 show ring. 



On the other hand, cow No. 2 and her descendants produce 

 at a rate that will not only keep their numbers good but will 

 admit of selection, and this is the case to a greater extent with 

 No. 3, whose descendants in the fifth generation would be no 

 fewer than 243 as compared with 32 for No. 2 and i for No. i. 

 It is easy to see that one such cow as No. 3 in a herd of 20 

 like No. i would in a few years, by very breeding powers, 

 dominate the herd, at the same time affording generous num- 

 bers for selection, whereas the descendants of No. i would 

 afford no opportunity whatever for selection. It is clear to the 

 most casual student that when our standards are decidedly 

 against the highest fertility they are dangerous, if not fatal, to 

 the race. 



Need of comparatively large numbers in breeding operations. 

 Obviously, comparatively large numbers are necessary in order to 

 provide selection with material sufficient for securing uniformity 



