Abstract:
Objective The melanocortin 1 receptor (MC1R) plays a critical role in mammalian pigmentation and coat color formation. Different MC1R alleles are associated with various coat color patterns in pigs. This study aims to explain the abnormal coat color segregation observed in the F1 hybrids of Duroc × Ding'an pig populations, thereby providing a theoretical basis for improving breeding efficiency and reducing economic losses in commercial production of crossbred pigs with black coat colour.
Method The MC1R genotypes of 10 piglets with red coat colors and 35 Ding'an pig sows were analyzed using PCR sequencing, specially focus on the A164V and A243T site of e allele in Durocs. Meanwhile, melanin content and the expression level of Tyrosinase (TYR), Tyrosinase related protein 1 (TRP1) and Dopachrome Tautomerase (DCT) in skin samples were examined through melanin staining and immunohistochemical staining.
Result Genotyping of the F1 hybrids and Ding'an sows revealed that 32 out of the 35 Ding'an sows were ED1/e heterozygotes, only 3 out of the 35 Ding'an sows were ED1/ED1 homozygotes, while all offsprings with red coat colour were e/e homozygotes. Results of Masson-Fontana staining and immunohistochemistry staining showed similar pigmentation levels between heterozygous and homozygous sows, which suggested that it is difficult to distinguish heterozygotes with homozygotes through histological analyses.
Conclusion Due to the fact that the prevalence of the introgression of e alleles from Druoc pigs into Ding'an pigs, the crossbreeding of Ding'an sows with Duroc sires would produce offspring with segregated coat colour, causing economic loss to the producer. Additionally, since it is difficult to distinguish between homozygous and heterozygous pigs based on their appearance, thus we reminder the producer to carry out of the genotyping of MC1R when producing crossbred with black coat colour by using Chinese indigenous pigs and Duroc pigs.
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