COLOR INHERITANCE IN SWINE 



Heredity Appears to be Mendelian — Some New Facts from Unusual Crosses- 

 Body Stripes Characteristic of the Primitive Wild Boar Have 

 Not Yet Been Eliminated 



B. 0. Severson, State College, Pa. 



MENDEL'S principles of unit 

 characters, dominance and seg- 

 regation seem manifested in 

 color characters of swine. 

 Smith ^ showed in the case of the York- 

 shire crossed with the Berkshire or 

 Poland China that white was dominant 

 over black in the Fi generation. 

 Secondly, in the F2 generation, the colors 

 showed "a general tendency for the 

 original parent colors to be expressed 

 separately and in the proportion of three 

 dominants to one recessive." Thirdly, 

 "in nearly all cases the recessive black of 

 the F2 generation carried more white 

 than the original black parents. This 

 suggests the requirement of a number of 

 germinal factors for each color rather 

 than a single factor." Q. I. and J. P. 

 Simpson^ in a study of crossing various 

 breeds of swine, state, "The exact 

 application of Mendel's law to all .swine 

 hybrids, where the initiative subjects 

 have been proven pure and homozygous 

 in gerin, and the similarity of process 

 in all sexual animals and plants in 

 chromosome reduction preparatory to 

 fertilization, leads us to conclude that 

 when pure they will all obey Mendel's 

 laws absolutely; and when marked 

 deviation in the hybridization is found 

 it is proof positive of contamination in 

 one or both subjects." 



In the spring of 1915 a litter was 

 farrowed, the result of mating a Berk- 



shire sow, Dora XVIII of Penn State 

 199,330 with a Duroc Jersey boar. 

 Fancy King 58,875. In this litter of 

 seven pigs, six were red with black spots 

 and one (see Fig. 17) was black with 

 white spots. In the spring of 1917 an- 

 other litter, the result of mating another 

 pure bred Duroc Jersey boar with a 

 pure bred Berkshire sow, produced 

 five pigs, four of which were red with 

 black spots and one black with the white 

 markings of a Berkshire. The appear- 

 ance of black and white in the Fi genera- 

 tion of this cross had never been ob- 

 served in a similar mating at the 

 Pennsylvania State College. Because 

 of this unusual case of a black and white 

 sow pig in the Fi generation (1915), she 

 was selected with a sister of the same 

 litter possessing the usual red and black 

 colors to be used for further investiga- 

 tion. In the case of the black and white 

 pig farrowed in 1917, its hereditary 

 color factors have not been investi- 

 gated. 



The black and white crossbred sow, 

 born in 1915, was designated No. I and 

 her litter mate was designated No. II. 

 These sows, (Fi generation) were both 

 mated at one year of age to a pure bred 

 Berkshire boar, Rival's Duke XXII 

 193,441, the object being to determine 

 whether the black and white sow. No. I, 

 possessed any hereditary factor for red. 

 Sow No. II was used as a check. 



Results of Mating 



Boar 



Breeding 



Sow 



Red and 

 black 



* Duroc Jersey, 58,875 Berkshire, 199,330 



t Berkshire, 193,411 Cross Bred No. I 



t Berkshire, 193,411 Cross Bred No. II 



* Fi generation, f F2 



Color of offspring 

 Black and Red, white 

 ■white and black 



6 1 



1 5 



2 4 



generation. 



1 Color Inheritance in Swine, American Breeder's Magazine, Vol. iv, p. 113. 

 -Analytical Hybridization, Proceedings A. B. A., Vol. vii, p. 266. 



Yellow 

 and black 



379 



