162 Maine Agricultural Experiment Station. 1919. 



ter-fat percentage and butter-fat of Jersey sires to their sons. 

 There were in this table 159 sires which had sons whose pro- 

 geny performance was known. Of this number 69 or signifi- 

 cantly-less than half had sons who raised the butter-fat pro- 

 duction of their daughters over that of their dams. Among 

 these sires who had sons of merit Signal's Crown Prince 61621 

 and Chief Engineer 47148 are the leaders. Among those sires 

 whose sons lowered the butter-fat productions of their daugh- 

 ters may be mentioned Merry Maiden's Grandson 91003 and 

 Ethleel 2d's Jubilee 18249. 



The sires of superior merit are defined as those which 

 raise the milk production and butter-fat percentage of their 

 daughters as compared with that of their dams. The inferior 

 sires are defined as those sires who lower the milk production 

 and butter-fat percentage of their daughters as compared with 

 the same variables in their dams. The superior sires so de- 

 fined % are arranged in table. 8 by the amount of butter- fat that 

 they increase the production of their daughters over that of 

 their dams. The inferior sires are classified' in table 9 accord- 

 ing to the amount of butter- fat that they decrease the produc- 

 tion of their daughters in comparison with that of their dams. 

 These two groups of sires are subjected to four generation pedi- 

 gree analysis to determine their inbreeding and relationship, 

 the amount of Island and American stock, "males and females" 

 and "on the sire's side of the pedigree and on the dam's side 

 of the pedigree," and the individual animals most frequently 

 repeated into two groups of pedigrees. 



There are 28 sires in the group of sires superior in their 

 transmitting qualities for milk production and butter-fat per- 

 centage. In the group of sires inferior in their transmitting 

 ability for these two characters there are 47 sires, a ratio of 1 

 to 1.7. Such a difference speaks for itself. It emphasizes with 

 startling clearness the need of exact knowledge of the trans- 

 mitting qualities of bulls to be bred as sires and of the neces- 

 sity for exact knowledge of the inheritance of milk production 

 and butter-fat percentage. 



The inbreeding coefficients show that the sires of superior 

 merit have 7.08 per cent of the greatest possible inbreeding up 

 to the fifth generation. The inferior sires are inbred 9.65 per 

 cent of the greatest possible amount (continued brother and 



