172 



The Journal of Heredity 



AGE OF DAMS IN MONTHS 

 FREQUENCY CURVE FOR DAMS 



FIGURE 13. The percentage of young born by dams of various ages is shown in this chart. 

 The age of the dams is computed for six-months periods, and the upper age limit of these groups 

 is shown. That is, all the dams 24 months and under are considered 24 months old, those between 

 24 and thirty months of age, as 30 months old, etc. It is evident that much the greater number 

 of calves are born by very young cows, the quality of whose offspring cannot be known. (See text, 

 p. 171.) 



