Lush: Inheritance in Swine 



6i 



THE PUREBRED DUROC- JERSEY WHICH WAS THE MOTHER OF THE FIRST Fi AND 



BACKCROSS GENERATIONS 



The Duroc-Jersey breed possesses drooping earsincontrast to the erect ears of the other breeds 

 used. All except two of the 29 pigs of the first generation from the Berkshire X Duroc-Jersey 

 cross had erect ears. (Fig. 9.) 



Of course it is likely that some of 

 these groups may contain more than 

 one phenotype, since the characters are 

 not definitely measurable ones, but the 

 variation from one extreme to the other 

 was by no means continuous and the 

 investigators believe that the number of 

 phenotypes which result from this 

 cross is quite limited. There was some 

 evidence of correlation between length 

 of face and dish of face because hogs 

 with both extremely dished faces and 

 extremely long faces did not occur, but 

 on the other hand, short-faced hogs 

 occurred with both extremely dished 

 and extremely straight faces. This 

 probably means that such correlation as 

 may exist is developmental or anatom- 

 ical rather than genetic (linkage). 



Other conclusions which may be 

 drawn with respect to face shape are 

 these: Several factors differing in im- 

 portance and in degree of dominance 

 are responsible for the anatomical dif- 

 ferences which have been considered 



under the title of face shape. Certain 

 of these factors affect certain parts of 

 the face much more than they do other 

 parts. The number of these factors 

 can not be so very large, else the paren- 

 tal types would not have been re- 

 covered among such limited numbers. 



SWINE COLOR 



The carefully controlled experiments 

 on swine which throw any light upon 

 the inheritance of the various colors 

 are not numerous and the resulting 

 interpretations which are established 

 beyond any scientific doubt are few 

 indeed. The whole subject has been 

 reviewed recently in the Journal of 

 Heredity by Wright* and, as far as the 

 author knows, since then there has been 

 only one notable addition to the litera- 

 ture upon the subject;^ therefore 

 what seems most likely to be the 

 truth about the inheritance of the 

 different colors found in swine will be 

 very briefly summed up as follows: 



« Wright, Sewall. 1918. Color Inheritance in Swine. Journal of Heredity, Vol. 9, pp. 33-38. 

 6 Lloyd-Jones and Evvard. Iowa Agricultural Experiment Station, Research Bulletin, No. 53. 



