242 



Bulletin 397 



TABLE 18. Relation of Age to Milk Production 

 (Averages of 60 cows for 5 lactations) 



It would be expected that the period of maximum seven-day production 

 of a cow would fall in or near the lactation of maximtim production. 

 This, however, has not been proved. The chief interest of the practical 

 breeder lies in the relation of age to the annual production of cows. Few 

 herd records contain enough data to give much light on this question. 

 While the limitations of the relatively small number of records are 

 recognized, the data are here included for what they are worth. They 

 represent all the records of cows that up to the present time have com- 

 pleted at least four lactations, recorded in the university herdbook. 

 These records, which have been kept for the past thirty years by Professor 

 H. H. Wing, include the records of some four hundred animals of all 

 breeds. 



The data from which the curves of milk production were made are 

 given in tables 19 to 25, inclusive: 



TABLE 19. Relation of Age to Milk Production 

 (Averages of 79 cows for 4 lactations. Age at freshening, 27 months) 



352 



