Butter-Fat Percentage in Jersey Cattle. 151 



fat percentage correlation coefficients is +0.5215 and the average 

 value of the milk yields is +0.5352. 



Of the sixteen average coefficients of correlation four of 

 those for the butter-fat percentage are higher than those for the 

 milk yield and four of them are lower. 



The greatest difference of these coefficients is — 0.0683. The 

 difference of the average values is — -0137. From the numbers 

 involved it seems probable that these differences are so small as 

 not to be significant. Such being the case it follows that the rela- 

 tive accuracy in the use of one lactation record to predict the 

 expected record of another lactation is approximately the same 

 for the butter-fat percentage and for the milk yield. In other 

 words the governing power (presumably the complex given the 

 animal through its inherited factor for these two characters) 

 works with about the same accuracy (as measured by its per- 

 formance) from lactation to lactation. This by no means would 

 necessarily mean that the inheritance of these two characters is 

 the same; in fact in all probability high milk production is gov- 

 erned more by dominant factors than is high butter-fat percent- 

 age. It only means that these factors once given an animal hold 

 it to the same relative level from lactation to lactation. 



If we make the point of environment, transfer our reasoning 

 to the race of Jersey Cattle with which we are dealing, these 

 records of the individuals in this race show a distinct differentia- 

 tion. The high individuals tend to remain high the low individu- 

 als low with respect to their butter-fat percentage just as they 

 also do with respect to their quantity of milk. Such a difference 

 can bespeak for but one thing the animals in this race are innately 

 differentiated with regard to their capacity to secrete a high con- 

 centration of butter-fat into their milk as well as they are for 

 the capacity to secrete the quantity of milk. 



Only one other economic product has been dealt with quan- 

 titatively by the correlation method. The correlation coefficients 

 in this case deal with the relation of the monthly Qgg production 

 to the other eleven months of the year. 



The correlations for these ovulation records range from 

 +0.240^.033 to +.573^.023. The range for the correlations 

 of butter- fat percentage is +o.247o±.o68o to +0.6781 ±.0310. 

 The range in these butter-fat percentage correlations is greater 

 than that for the ovulation records of the White Leehorn hen. 



