272 Maine Agricultural Experiment Station. 1919. 



b. What is the relation between the milk production of a 

 short period and the milk production of a subsequent whole 

 lactation of which the short period is not a part? 



. In answering this question the author quotes from some 

 unpublished data soon to be put in bulletin form. 



The range in values of the correlation coefficients for milk 

 yield of the seven day test with the milk yield of the year test in 

 another lactation is +0-335 1 to -fo.8470. For the seven day test 

 with the year test of the same lactation the range is — 0.1157 

 to -[-0.8470. For the parts considered in determining the con- 

 formation the range is -(-0.1941 to — 0.0697. 



The average correlation coefficient for the 7 day test of 

 Holstein-Friesian cattle and the 365 day test of which the seven 

 day test is a part is -I-0.570. The average correlation coefficient 

 for the 7 day test and 365 day test of which the 7 day test is 

 not a part is -I-0.550. In other words a seven day test is a much 

 better measure of a cow's ability at the pail than is the total 

 score or any part of the cow's conformation as judged by the 

 average trained dairyman. This general relation between the 

 milk yields of the various length of periods has been found to 

 hold for the other breeds. 



Breeding Experiments. 



The experiments in cattle breeding which have been car- 

 ried out in cooperation with the University of Maine have pro- 

 gressed satisfactorily this year. These experiments, as pointed 

 out in previous reports, are definite crossbreeding experiments 

 so planned as to furnish data on the inheritance of milk, butter- 

 fat and butter-fat per cent. The object of this work is conse- 

 quently not to obtain an animal which shall be a high milker 

 with a high percentage of butter- fat but rather to determine 

 the laws of heredity behind the transmission of these qualities. 

 In this way and in our present knowledge in this way only can 

 the breeding for better dairy cattle within the different breeds 

 be intelligently accomplished. 



