PRINCIPLES OF LIVESTOCK BREEDING. 



33 



COLORS OF SHEEP. 



The color of black sheep is recessive to the ordinary white color. 

 It can thus appear only when transmitted by both ram. and ewe. It 

 is well to remember that a single black lamb in a flock indicates 

 that the ram is transmitting the unit for black in half his sperm cells. 

 Half of his daughters may thus be expected to transmit it. 



COLORS AND COMB SHAPE OF POULTRY. 



The mode of inheritance of the colors of poultry is still far from 

 thoroughly worked out, but a few points may be mentioned. The 

 barred pattern of Plymouth Rocks and several other color patterns 

 are linked with sex in the way which has already been discussed. 



Fig. 8.— A daughter of the stallion in figure 7. Note the inheritance of the spotted coat pattern and 



curby hocks. 



The Blue Andalusian has a color which is inherited in a way similar 

 to the roan of Shorthorn cattle. It is a color which can not be fixed. 

 Blue by blue produces only 50 per cent blues, the rest being equally 

 divided between blacks and splashed whites. It is possible, how- 

 ever, to produce 100 per cent blue chicks by crossing the blacks and 

 whites with each other. 



The mode of inheritance has been worked out for a number of 

 characteristics of poultry besides color. Thus rose comb is dominant 

 over single comb and behaves as if it differed only in one unit factor. 

 The pea comb of Indian Games and Brahmas is also dominant over 

 single comb but depends on a variation of a different unit factor. 

 The combination of rose and pea comb results in the walnut comb 

 of the Malay breeds. 



5254°— 20— Bull. 905 5 



