Location: Livestock Bio-SystemsTitle: A GWAS of teat number in pigs
Submitted to: International Society for Animal Genetics (ISAG)
Publication Type: Abstract Only
Publication Acceptance Date: 4/22/2016
Publication Date: 7/23/2016
Citation: Rohrer, G.A., Nonneman, D.J. 2016. A GWAS of teat number in pigs [abstract]. International Society for Animal Genetics (35th ISAG). Abstract Book. p. 131-132 (Abstract # P5033).
Technical Abstract: Number of functional teats is an important trait in commercial swine production. As litter size continues to increase, the number of teats must also increase to supply nutrition to all piglets. The pig displays considerable variation for number of teats; therefore, a genome-wide association (GWA) analysis was conducted to identify genomic regions that affect this trait in a commercial swine population. Genotypic data from the Illumina Porcine SNP60v1 BeadChip were available for 2,951 animals with total teat number (TTN) recorded. A subset of these animals (n=1,828) had number of teats on each side recorded. From this information, the following traits were derived: number of teats on the left side (LTN), number of teats on the right side (RTN), the maximum number of teats on a side (MAX), the difference in LTN – RTN (L-R) and the absolute value of L-R (DIF). After data editing, 41,148 SNP markers were included in the analysis implementing the Bayes C option of GENSEL (version 4.61) and 1 Mb windows. Fixed effects fitted in the model were season of birth and a regression coefficient for the number of copies of the ancestral vertnin allele. Marker heritabilities were highest for TTN (0.233), intermediate for individual side counts (0.088 to 0.115) and virtually nil for difference traits (0.002 for L-R and 0.006 for DIF). Each copy of the mutant vertnin allele increased teat count by 0.35 (TTN), 0.16 (LTN and RTN) and 0.19 (MAX). The number of 1 Mb windows explaining more than 1% of the genomic variation detected was 15 for TTN, 18 for LTN, 13 for RTN and 18 for MAX. These regions cumulatively accounted for over 50% of the genomic variation of LTN, RTN and MAX, while only explaining 30% of the genomic variation of TTN. Ten 1 Mb windows were associated with more than one trait. Most notable was SSC 10:52 Mb which was associated with all four traits, while SSC 10:60 Mb and SSC 14:54 Mb were associated with three of the four traits. Further research on these regions should yield markers that could be used to increase the number of functional teats in commercial pigs.