Four major loci 1 Extension locus E Ep and e alleles Hog color inheritance a Differences in genotypes at this locus result in black vs black spotted vs non black based colors all with dark skin 2 Dilution locus D and d alleles a Presence of the D alleles causes dilution of red to sandy in heterozygotes and to white or off white in heterozygotes That is the D allele causes dilution of red color but not of back color 3 Pattern locus K and k alleles a Homozygosity of the k allele causes hogs with a black spotted base color to be black with six white points feet nose and tail 4 Inhibition locus I IL and I alleles a Homozygotes of the I allele have full expression of their base color b Presence of the IL allele cause a white belt on colored hogs c Presence of the I allele inhibits pigment formation resulting in white i Homozygotes of the I allele are totally white ii Heterozygotes of the I allele are at least predominantly white 1 Hogs with the E Ii or E IIL genotypes are blue butts 2 Hogs with the EP d Ii ee DD Ii EP DD IIL or ee DD IIL genotypes are white however some have a few dark skin spots 3 Hogs with the EP d Ii ee d Ii EP d Ii EP d IIL or ee d IIL genotypes are white however many have a red tint to the hair and some have a few dark skin spots most black and white spotted hogs have some white skin there is evidence that there are at least two separate dilution loci with cumulative effects there is a fourth allele ID at this locus that is present in at least some of the white breeds Hogs that have the IDi or IDIL genotype have more color than hogs with the Ii or IIL genotype in at least some genetic combinations Locus Most dominant Next in order of dominance Most recessive E Ep e Extension pattern inhibition Order of dominance Dilution D d K k IL i No dominance at the dilution locus That is the heterozygote is intermediated to the two alternative homozygotes only red color is diluted IMPORTANT NOTES 1 All hogs that have the I allele are at least predominantly white a Homozygotes II are completely white regardless of their genotype at the other three loci b Heterozygotes either IIL or Li will be at least predominantly white as discussed on the previous page note that blue butts are predominantly white 2 Hogs that are E ii are black regardless of their genotypes at the other two loci Those that are E ILIL or E ILi are black belted regardless of their genotype at the other two loci 3 Assume that all hogs that are EPEP kk ii or EPe kk ii are black with six white points regardless of their genotype at the dilution locus the actual inheritance mat be at least somewhat more complicated than this Breed Hampshire Duroc Yorkshire Landrace Chester White Description of breeds Typical Genotype Typical Color EE dd KK ILIL Black with white belt ee dd KK ii Red EPEP DD KK II white EPEP DD KK II White EPEP DD KK II White Spot Poland China Berkshire EPEP DD KK ii Black and white spotted EPEP DD kk ii Black w 6 white points EPEP DD kk ii Black w 6 white points Types of alleles by breed The ID allele has a fairy low frequency in the landrace Therefore most landrace are homozygous for I the ID allele may also be present in the Yorkshire and Chester white at low frequency Example what colors and proportions are expected if F1 Hampshire Yorkshire boars are bred to F1 Hampshire Yorkshire sows Hog skin pigmentation and spotting The I allele inhibits pigmentation in hogs Therefore pigs that have II at the inhibition locus are white with light skin pigmentation When pigs have ii at the inhibition locus pigmentation is not inhibited allowing pigs to have a dark skin pigmentation An example of a genotype that would result in a pig that is white with dark skin pigmentation is iieeDDKK Below are pictures of the different whites White with light skin pigmentation White with dark skin pigmentation The EP allele creates black spotting when the rest of the genotype allows for it These spots look different than dark skin spots Dark skin spots only affect the skin pigmentation and not the hair We can see these in predominantly white pigs Black spots affect both skin and hair pigmentation sometimes the black skin pigmentation extends beyond the black hairs Pigs that are red sandy or white can have black spots Below is a picture of each type of spotting Dark skin spots Black spots Hog color inheritance o Back with White bet or black belted Hog breeds Hampshire Duroc o Red Yorkshire o White Landrace o White Chester white o White Spot Poland China o White with black spots or black an black spotted o Black with 6 white points Nose four feet and tip of tail Berkshire o Black with 6 white points Four major loci 1 Extension locus EP and e alleles 2 Dilution locus D and d alleles 3 Pattern locus K and k alleles 4 Inhibition locus I IL and I alleles Order of dominance No dominance at the dilution locus the heterozygotes is intermediate to the two alternative homozygous only rede color is diluted Extension locus E black EP black spots on a non black background Ee non black red sandy or white Dilution locus of red color dd no dilution Dd dilution of red to sandy DD dilution of red to white Pattern locus on hogs with black spotted base colors K not expressed kk express black with six white points inhibition locus ii full expression of base color IL causes white belt on colored hogs I results in white hogs some variation II white E E back with white front feet o Ii or IIL at least predominantly white blue butts white however some have a few dark skin spots white however many have a red tint to the hair and some have a few dark skin spots EP dd red with black spots and white feed EP dd red with black spots EP Dd sandy with black spots and white feet EP Dd sandy with black spots EP DD white with black spots spots Ee dd red Duroc Ee Dd sandy light Ee Dd sandy Ee DD white with dark skin mangalitsa Stripes on baby pigs EEEPDDK white with black spots EPEPDDKK black with six white points Berkshire EP DDkk black with six white points E ii black EE dd KK ILIL black with white belt hampshire E IL black with partial belt E IL back with wide belt E IL black with very wide belt back headed EP DD K ii white with black spots spot EP DD K IL white with black spots and white belt EP Dd K ii sandy with back spots EP Dd K IL sandy with black spots and a white …