CHAPTER VIII 



Characteristics of Pedigrees for the Different Breeds 



relationship 



Within any pedigree a state of relationship exists if the sire and 

 dam of the animal pedigreed have common ancestors, or putting 

 it another way, two individuals are related if they have common 

 ancestors. The calculation of the relationship coefficients is much 

 like that for inbreeding save for one particular, namely, that for 

 any one generation it is possible to have only half the number of 

 animals related as compared with those which are inbred. Such 

 being the case the denominator of the fraction in any generation is 

 half the number of animals in that generation. The coefficient of 

 kinship or relationship is noted by K. 



Turning back to the pedigree of Rioter's Jersey Lad, we note that 

 there are no common ancestors for the sire and dam up to the 

 fourth generation. Such being the case K 2 and K z are both in 

 value. In the fourth generation A 4 , Bachelor of St. L. and Ida of 

 St. L. are common to both sire and dam so that the coefficient of 

 relationship is 2 divided by 8 or 25 per cent. 



The student may calculate the kinship found in each of his four 

 pedigrees. Tabulate the kinship coefficients for the pedigrees of 

 the whole class, tabulating each group separately as was done for 

 the inbreeding. See pages 51-54 for protocols. Compare the 

 average per cent of relationship found in the pedigrees of the four 

 groups. What conclusion do you draw as to the influence of rela- 

 tionship on the recorded producing power of an animal. 



REFERENCES 



Read Chapters II and VII of M. S. for the discussion of kinship. 

 Maine Station Bulletin 281, Studies in milk secretion VII. 

 Pearl, Raymond. September, 1917. Studies on inbreeding VII, American 

 Naturalist, vol. LI, pp. 454-559. 



Other sources of information will be suggested by these references 

 which it would be well for the student to follow up. Write a short 

 paper on the influence of relationship. 



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