Wright : Bates' Duchess Cattle 



415 



|00%- 



80 



0% 



-o 60 



c 



^ 40 



MO 



'5 -4. -3 -2 -I I a 3 4 5 6 7 8 



Qen«ratcon5 jrom DucH'M I 

 DEGREE OF INBREEDING OF THE DUCHESSES 



Figure 24. The degrees of inbreeding of the Duchesses (solid line), of their sires 

 (broken line), and dams (dotted line). The original Duchess was purchased by Charles 

 Colling in 1784. Duchess I, five generations later, was purchased from Colling by Bates, 

 who bred eight generations, including sixty-three cows, before his death in 1849. The 

 coefficient of inbreeding measures the approach toward complete homozygosis. The 

 coefficient of 40 per cent maintained by Bates means 40 per cent less heterozygosis than 

 was present in the foundation stock. 



er of his own or other breeding, which 

 were inbred to substantially the same 

 extent, 40 per cent, as the cows and 

 related to them as we have seen, about 

 60 per cent. With regard to factors 

 in which the original Shorthorns were 

 only 50 per cent homozygous, the sires 

 used by Bates and his whole Duchess 

 family were about 70 per cent homo- 

 zygous from the automatic efifect of 

 inbreeding alone. 



Relationship to Favourite 



Finally it is interesting to see how 

 far Bates maintained relationship to 

 the bull, Favourite, about which as we 

 have seen the Colling^s centered their 



efforts at the improvement of Short- 

 horns. Figure 25 shows the coefficients 

 for the generations of Duchesses in 

 the solid line and those for their dams 

 and sires in dotted and broken lines 

 respectively. Favourite himself a.p- 

 pears as a sire of two of the early 

 Duchesses bred by Colling. Bates' 

 Duchess I shows a relationship of 76 

 per cent. During the following genera- 

 tions bred by Bates, the relationship 

 slowly falls from 69 per cent to about 

 57 per cent. It is noteworthy that the 

 sires, the majority of which were bred 

 by others, show practically the same 

 coefficients as the Bates-bred cows with 

 which thev were bred. 



