The Possibility of TBC1D21 as a Candidate Gene for Teat Numbers in Pigs

Genotyping by sequencing reveals a new locus for pig teat number

Teat number is an extremely valuable trait for sow reproduction performance and piglet survival. Here, we used genotyping-by-sequencing and a general liner model to carry out genome-wide analysis of sow total teat number in an Erhualian population. The results indicated that eight SNPs on chromosomes 4, 5, 9 and 10 were significant genome wide (Bonferroni method, P < 2.85E-7) for sow total teat number. Validation analyses were performed in 298 Erhualian and 904 Large White sows using these significant SNPs and the general liner model procedure in sas. Finally, only the SNP on chromosome 5 was found to be significantly associated with sow teat number in both populations. The GG genotype individuals had 2.23 and 0.82 more teat numbers respectively than did the AA genotype individuals in these two populations (P < 0.05). According to the expression and annotation analyses, we inferred the presence of a gene or lincRNA that could affect teat number by regulating other genes and ultimately affecting the mammogenesis of pigs. Further studies using methods such as Cas9 editing and gene silencing analysis are necessary for additional function analysis.