218 Maine Agricultural Experiment Station. 1920. 



low milking factors from the high milking factors carried by 

 her dam. 



Three levels of milk production are crossed in these experi- 

 ments. The Aberdeen Angus cattle constitute the lowest level, 

 the Jersey, Guernsey and Ayrshire cattle averaging about the 

 •same in milk yield constitute the intermediate level of produc- 

 tion and the Holstein-Friesian cattle having the highest yield 

 represent the highest level of production. It is of some interest 

 to compare the results of crossing the different levels. If we 

 .omit the result of Crossbred No. i it is found that the Holstein- 

 Friesian cows or bulls mated to the second group of cows or 

 Ibulls (Jersey, Guernsey or Ayrshire) produced offspring who 

 ,are 8.43 times as near the milk production of the high level on 

 the average as they were the low line of production. 



The only cross involving the Holstein-Friesian and Aber- 

 deen Angus, Crossbred No. 44, was 2.2 times as close to the 

 high line of production as she was close to the low line of her 

 •parent's milk yield. 



It is of interest to note in this connection that Crossbred 

 "No. 44's milk yield resembles closely the milk yield of the in- 

 termediate group (Jersey, Guernsey and Ayrshire) of these 

 .experiments. 



The crosses involving the second level of milk production 

 • (Jersey, Guernsey and Ayrshire) mated to the third group 

 Aberdeen Angus, had crossbred offspring resembling the high 

 'line J."/ times as closely as they did the low line of production. 

 This figure compares favorably with that of the Holstein-Frie- 

 :sian x Jersey crosses. 



If the crosses are compared to determine what effect the 

 high line on the sire's side of the cross may have in comparison 

 with the effect produced by the high line being on the dam's 

 side of the cross it is found that the results in the three lines 

 .are contradictory. When the Holstein-Friesian sires were mated 

 to second class dams, Guernseys, the offspring resembled the 

 high line 1 1.3 times as closely as she did the low line. When 

 the fersev sire, second class, was mated to the Holstein-Friesian 

 cows, highest class, the milk production of the offspring, once 

 resembled the high class 2.7 to 1 and once the low line j.y to 1. 

 The crosses involving the highest milk line, Holstein-Friesian 

 bull, to the lowest milking line Aberdeen Angus cow producer 



