298 



MASS. EXPERIMENT STATION BULLETIN 258 



IIIBRE3 DAMS 

 CHECK DAM3 



— — - IBBRSD DA'JOHTSRB 



— ' — « •- CHECZ D*UGHT£R8 



iga"* 



1935 



1927 



192a 



UATINO YIAHS, 

 CHART 6. — Effect of Inbreeding on Persistency 



Chart 6 indicates that all the check breeders which actually produced daugh- 

 ters showed genetic high persistency or the ability to lay for 315 days or more 

 before molting. The inbred mothers also ran high in persistency until 1926, 

 1927 and 1928, when they decUned to 75 and 80 per cent highly persistent. 



The check daughters showed but 27 per cent high in persistency in 1923 and 

 increased to 100 per cent in 1925. When the check groups were inbred the re- 

 sulting daughters declined to 67 and 45 per cent high in persistency in 1926 and 

 1927. Inbred daughters were 100 per cent highly persistent the first year of 

 the experiment. In the second year of inbreeding only 40 per cent carried high 

 persistency, and in the third year the figure was 60 per cent high. When the 

 inbred strains were intercrossed there was some increase in the proportion of 

 highly persistent birds, the final figure being 82 per cent high. These data indi- 

 cate that inbreeding has reduced persistency. This fact appears both in the 

 original inbred groups and in the check groups when inbred. A rather significant 

 point also is the fact that daughters resulting from crossing inbred strains did not 

 exhibit as high persistency as the inbred daughters appearing in the first genera- 

 tion of inbreds in 1923. 



230 



220 

 2X0 

 200 

 190 

 ISO 

 170 

 160 

 150 

 lUO 



INBRED DAU3 

 CHECK DAUB 



IHBRED OA'JGHTERa 



! I CHECK DAUOHTERfl 



/ 



192} 



192ii 1925 



UATINO YEARS 

 CHART 7. — Effect of Inbreeding on Annual Producti 



192* 



