MEN DELI SM IN DOMESTIC ANIMALS 



467 



TABLE LXI. THE TRANSMISSION OF COAT COLOR IN HORSES IN VARIOUS TYPES op 



MATINGS 



Wentworth, Cole found in tabulating the offspring of gray mares re- 

 corded in the Clydesdale studbook that exactly 50 per cent, were gray 

 and 50 per cent, not gray, which is in strict conformance to expectation. 

 Roan is a coat color characterized by a slight sprinkling of white hairs 

 in a pigmented coat. The roan color is even less popular in breeds than 

 gray, and it occurs to any great extent only in Belgian draft horses. The 

 roan factor, R, is a dominant pattern factor independent of any of the 

 color factors. It is, therefore, possible to have gray roans, red roans, 

 blue roans, and chestnut roans according as the pigmented coat color is 

 gray, bay, black, or chestnut, respectively. Gray roans are not dis- 

 tinguishable from ordinary gray of course, except at birth, so that this 

 class is merely a genetic one not recognized in practical breeding opera- 

 tions. At birth gray foals are black, whereas gray-roans are black 

 with interspersed white hairs. The data of Table LXI indicate plainly 

 enough that roan is a dominant color, but some reports of individual 

 animals are even more interesting. Thus J. Wilson reports that a red- 

 roan Belgian stallion standing for service in Story County, Iowa, was 

 bred to all classes of mares, but all of the 256 foals he sired were 

 red-roan like himself. Another red-roan stallion sired 254 colts of which 

 230 were red-roan and the remaining 24 blue-roan. These two stallions 

 must have been homozygous for the roan factor, and their breeding re- 

 cords establish clearly the dominance of the roan coat color pattern. 



