172 Essay on the Interpretation of Milk Records. 



With these alterations the frequency curve of range of 

 variation of individual cows gave the following results : — 



Mean of range of individual variations, corrected for age and season, 480 quarts. 

 Median „ „ ,. ,, „ 4-36 „ 



Mode „ „ „ „ „ 3-48 „ 



The improvement in the mode so far effected is as 

 follows : — 



Uncorrected Mode .... 6'98 quarts 

 Corrected for age .... 3-97 „ 

 Corrected for age and season . . 3"48 ,, 



and is shown in the following figures giving the three 

 frequency curves together. 



Fig. 8.— Individual Variation (Range) in Quarts. 

 In 110 Cows during 6 years. 



25 



% 20 



o 



O 15 f 



2-. P; 



12 3 4 5 



10 11 12 13 14 15 16 17 18 19 2J 



Iiifi'uence of period of " 7^est " hefore calving. The R.M, of 

 347 records were divided into groups according to the number of 

 weeks the cows were dry before calving. The means of these 

 groups were as follows : — 



No correction is therefore made to the R.M. on this account. 

 It is by no means intended to imply that the period of rest 

 before calving is of no importance ; on the contrary most 

 dairy farmers will agree that it has a very considerable 

 influence on the subsequent performance, and more especially 

 condition of a cow. What is meant is that, in this method of 

 classing a cow b}" her R.M., variations due to this cause are 

 slight in comparison to the unaccountable irregularities always 

 present. 



Note 1. On the practical use of the R.M. — Such a figure 

 is, it is thought, an obvious necessity for determining the 



