THE SELECTION PROBLEM IN ANIMAL BREEDING 507 
egg production in the domestic fowl by Harris, Blakeslee and Warner. 
This study dealt with the relationship between the concentration of 
yellow pigment in the ear lobe of White Leghorn hens and their egg re- 
cords of the preceding months. It was found that there is a very close 
interdependence between October ear-lobe color and the egg production 
of the pullet year. 
“Expressed in absolute instead of relative terms, the correlations 
determined indicate that on an average birds differing by 5 per cent. in 
the amount of yellow in the ear lobe will differ by about 7 eggs in their 
annual production. Thus the difference is one of real practical signific- 
ance. For example, birds showing only 10-20 per cent. of yellow in their 
ear lobes in October will have laid on an average about 185 eggs each, 
whereas birds exhibiting 55-65 per cent. of yellow will have an average 
annual production of only about 130 eggs.” 
These results prove that in the fowls used in this investigation color 
of the ear lobe (and presumably, of the leg, beak and vent) would have 
served as a practical index for selection of high layers. The authors 
point out, however, that the flocks from which their data were obtained 
represent a selected class of birds (in certain egg laying contests). ‘Such 
birds show, because of better breeding, better feeding and care, or both, 
a far higher annual egg production than the average flock. Unfortun- 
ately data of the kind presented here are not as yet available for the 
unselected class of layers.”” This correlation has long been known and 
utilized by poultry breeders (according to Kent it was noted in published 
form in 1879) and Blakeslee and Warner made earlier statistical studies 
than the one we have considered. Both Kent and Warner point out that 
degree of pigmentation is only one of several characters that may be 
utilized in selecting high laying hens, the other more important ones being 
time and duration of molting and size of abdomen. 
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