Studies in Milk Secretion 145 



or as occurring on the dam's side of--the pedigree. By a com- 

 parison of this information for the superior sires with the cor- 

 responding information on the inferior sires some insight may 

 be gained as to the effect of inbreeding and relationship in 

 making a superior or inferior sire and as to the relative values 

 of American and Island breeding. Table 10 gives this infor- 

 mation for the sires of table 8 classified according to their 

 merits as was . done in that table. 



In the first three columns of table 10 are given the num- 

 ber, name and registry number of the sire. The four follow- 

 ing columns contain the inbreeding for each generation and the 

 constant expressing the amount of inbreeding in relation to 

 the maximum possible amount of a continued brother and sis- 

 ter mating. These figures show that no inbreeding has taken 

 place in second generation in the pedigree of these twenty-eight 

 superior sires. In the third generation nine bulls had a repeated 

 ancestor in their pedigree. Out of the twenty-eight sires all 

 but five had some inbreeding before the fifth generation. The 

 total ranges from o to 20.6 per cent of what could occur for 

 a brother and sister mating. The bull exhibiting the greatest 

 amount of inbreeding was Rioter's Jersey Lad. The pedigree 

 of this bull is given on page 146. 



The animals marked with the solid circles are repeated 

 previously in the pedigree. These marked with an open circle 

 containing a cross are ancestors of repeated animals. In this 

 pedigree the repeated animals are Ida's Riotor of St. Lambert, 

 Bachelor of St. Lambert, Ida of St. Lambert and Ida's Stoke 

 Pogis. The inbreeding which occurs in the pedigree of this 

 bull is 20.6. The average Coefficient of total inbreeding for 

 this group of bulls is 7.08 per cent of that which would have 

 occurred in continued brother and sister matings. 



The next three Columns are taken up with the coefficients 

 showing the degree of relationship within the pedigrees. No 

 bull in the pedigree had ancestors which were related in the 

 second generation. In the third ancestral generation there were 

 only four sires' out of the twenty-eight which had related an- 

 cestors. In the fourth generation ten sires had ancestors known 

 to be related. The pedigree of Rioter's Jersey Lad 58001 

 shows such related ancestors in Bachelor of St. Lambert and 

 Ida of St. Lambert. 



