GENETICS OF HEREFORD CATTLE 



W. E. Castle and W. L. Wachter 

 Harvard University, Cambridge, Mass. 



FEW attempts have been made as 

 yet to apply to the larger and 

 more valuable domestic animals 

 the principles of genetics worked out 

 in the case of laboratory animals and 

 plants which can be reared in large 

 numbers at relatively small expense. 

 Direct experiment with horses or 

 cattle for the demonstration of genetic 

 principles has rarely been undertaken, 

 but some incidental observations have 

 been recorded in regard to breeding op- 

 erations with such animals conducted 

 primarily for economic reasons. A 

 valuable set of observations of this lat- 

 ter type made upon a large herd of 

 pedigreed Hereford cattle has recently 

 been published.^ It is a first contribution 

 toward a genetic analysis of the dis- 

 tinctive color pattern of this breed. 



The "typical Hereford" is described 

 as "a deep red beast, with white face 

 and underparts, white feet, white at 

 the end of the tail, and with a white 

 patch along the top of the neck. Some- 

 times there is a trace of red round the 

 eyes. The stranger to the breed is 

 generally impressed by the constancy 

 of these markings; still variations from 

 the type do occur. It is hardly nec- 

 essary to add that the Hereford is a 

 very heavy fleshed beast, fattening 

 rapidly, and is the premier beef breed 

 of the world, having spread to every 

 country where beef raising is a con- 

 siderable industry." See Fig. 27. 



"Minor points that breeders attend 

 to are: coat color, which should be a 

 rich purple red, not a yellow-brown; 

 a clean, clear nose, without spots or 

 markings; and the horns, which should 

 be free from pigment at the tips." 



The salient points in the foregoing 

 description relate to the quality and 

 distribution of pigment in the coat. 

 As regards quality, the desired shade is 

 an intense red (never black) distributed 

 throughout the coat except where white 

 is found. White occurs in a funda- 

 mental pattern seen in many breeds 



of European cattle. Ramm^ depicts 

 some seven different breeds of cattle 

 from different parts of continental 

 Europe which show this same funda- 

 mental pattern, in which white occurs on 

 the head and extends thence ventrally 

 along the "underline" to the tail, and 

 dorsally as a spinal white stripe to the 

 shoulders or even to the rump, thus 

 nearly (in extreme cases quite) encirc- 

 ling the animal in the median plane. 

 Cattle of this general pattern kept in 

 Herefordshire, England, in the 17th 

 century formed the foundation stock 

 from which the modern Hereford breed 

 apparently was evolved. The genetic 

 analysis of the breed, made in the 

 paper under review, indicates that 

 specific Mendelian modifying factors 

 have in the past two centuries and a 

 half been incorporated in the breed, 

 having perhaps originated by a series 

 of minor mutations, which systematic 

 selection has seized hold of and re- 

 tained as distinctive features of the 

 modern breed. The author identifies 

 five unit-character variations which 

 may be regarded as having been added 

 to the genetic complex found in the 

 ancestral Herefords and in various 

 other breeds of cattle possessing the 

 same pattern of median plane white on 

 a colored background. The five hypo- 

 thetical Hereford factors are: 



1. A whitening factor, W, which 

 modifies what would otherwise be a 

 typical Hereford (grade 0, Fig. 28) to 

 one having an "excess of white," as 

 illustrated in grade -1 to -4, Fig. 28. 



2. A darkening factor, D, having an 

 effect contrary to that of the whitening 

 factor. It changes what would other- 

 wise be a typical Hereford (grade 0) 

 to one of grade +2 or +3, Fig. 28. 

 The greatest change is noted in the 

 neck region, hence the factor is called 

 the "dark neck" factor, although its 

 effects are not restricted to that region 

 of the body. 



1 Frances Pitt. Notes on the inheritance of color and markings in pedigreed Hereford cattle. 

 Journal of Genetics, 9, Feb. 1920. 



2 Ramm, E., 1901. Die Arten und Rassen des Rindes. Stuttgart. 



37 



