Apr. 24. 1916 A Sex-Limited Color in Ayrshire Cattle 143 



PROGENY OF MELROSE GOOD GIFT FROM RED-AND-WHITE COWS 



Fifteen red-and-white cows in the herd were mated to Melrose Good 

 Gift to produce 20 calves, of which 10 were black-and-white bulls and 10 

 were red-and-white heifers. All of the bulls were as red as the heifers 

 at birth, but at 2 to 4 months of age the blackish tinge began to develop, 

 and within 4 months the youngsters became distinctly black-and-white. 

 The heterozygous male progeny of Melrose Good Gift differed from the 

 homozygous male progeny in that the black tinge developed more slowly 

 and also became much less intense on maturity. While in the mature 

 homozygous bull the black is very distinct throughout the pigmented 

 areas, in the mature heterozygous bull the black may appear only as a 

 streaked border where the pigmented spots adjoin the white, or at the 

 limbs, muzzle, ears, and tail. The main portions of the colored parts of 

 the animal are usually a very dark red which blends gradually, although 

 in a particulate manner, into the blacker borders. The heterozygous 

 heifers are red-and-white, and while occasional dark hairs are found, no 

 regular means whereby the heterozygous red-and-white females could be 

 distinguished from the homozygous red-and-white females was discov- 

 ered. It should be further noted that the black color of the homozyg- 

 ous female is by no means as intense as that of the male, although the 

 black is indisputably present. 



HETEROZYGOUS BLACK BULLS TO HOMOZYGOUS RED COWS 



Johanna Croft King, College Marquis, Sir Croft of Spring City, Wool- 

 ford's Good Gift, and Lessnessock Oyama's Good Gift were bulls which 

 by their breeding performance and somatic description must have been 

 heterozygous for the black factor. The last two bulls were found in the 

 pedigree of Melrose Good Gift, while the first three were used at one time 

 or another at the college as herd bulls. Records of these in matings to 

 homozygous red-and-white cows were available for all except Woolford's 

 Good Gift, and the result showed four red-and-white heifers, four black- 

 and-white bulls, and 5 red-and-white bulls. This is the most probable 

 distribution of colors in both the males and females and is perfectly in 

 alignment with the interpretation of the method of inheritance as given. 



The reciprocal cross of red-and-white bulls to black-and-white cows 

 gave two black bulls to one red bull and two white heifers, also the most 

 probable expectation. 



BLACK-AND-WHITE COWS MATED TO RED-AND-WHITE BULLS 



Only three calves were available from this type of mating, all red-and- 

 white daughters of Bangora, the original black-and-white cow in the 

 herd. While the numbers are too small to be conclusive, yet they 

 conform to the expectation. 



