Analysis of Association Between a Microsatellite at Intron 1 of the Insulin-Like Growth Factor 1 (IGF1) Gene and Fat Deposition, Meat Production and Quality Traits in Italian Large White and Italian Duroc Pigs

Abstract

A few studies have shown that a microsatellite at intron 1 of the insulin-like growth factor 1 (IGF1) gene is associated with several production traits in a few pig populations. In the current work we evaluated associations between this microsatellite and production traits in Italian Large White and Italian Duroc pigs. Association studies were carried out on a total of 1120 animals using two experimental designs: i) a selective genotyping approach based on extreme and divergent Italian Large White pigs for back fat thickness (BFT) estimated breeding value (EBV) or on extreme and divergent Italian Duroc pigs for visible intermuscular fat (VIF) EBV; and ii) analysis of unselected pigs (random groups) coming from populations of the two breeds. Allele distributions between Italian Large White and Italian Duroc pigs were different (P<0.05) with longer alleles being more frequent in Italian Large White. Results of the association analyses from two different random groups showed that this marker affects average daily gain EBV, lean cut EBV and BFT EBV in Italian Large White and BFT EBV in Italian Duroc (P<0.05). Association analysis carried out with random residuals confirmed, to some extent (P=0.096), the effects on BFT in the same animals. However, this result was not confirmed in the two extreme and divergent Italian Large White groups used in the selective genotyping experiment. These inconsistent results may indicate that the effect of the IGF1 microsatellite is doubtful in the investigated finishing pigs.

Investigation of a Short Interspersed Nuclear Element Polymorphic Site in the PorcineVertninGene: Allele Frequencies and Association Study With Meat Quality, Carcass and Production Traits in Italian Large White pigs

“…Pigs were chosen according to their estimated breeding value (EBV) for BFT (280 pigs with most negative and 280 with most positive EBV) within a performance tested population of ~12,000 pigs (details of EBV calculation are reported below). All sampled pigs were at least two-generation unrelated (Fontanesi et al, 2012;2013b). Average BFT EBV in the negative and positive selected groups of pigs were -9.4±1.6 mm and +8.0±5.95 mm, respectively.…”

A Poly(dA:dT) Tract in the IGF1 Gene Is a Genetic Marker for Growth Traits in Pigs

“…A previous study has showed that the polymorphism of CA repeats microsatellites near the tract 2 in the IGF1 promoter was significantly associated with plasma IGF1 concentration in pigs. The longer genotype of CA displayed a higher live weight in Landrace boars, a higher carcass weight in Duroc [ 32 ], and a higher average daily gain in Large White [ 33 ], but there was no clear relationship between the CA repeats and growth rate in Shanxi White pigs, a Chinese domestic breed [ 34 ], and these observations suggested that the CA repeats in the IGF1 promoter are important elements that regulate the transcription and function of IGF1 in pigs. Moreover, the CA repeats are near the tract 2 in the IGF1 promoter, indicating that CA repeats may link with the poly(dA:dT) tract in pigs, and it was likely that the effects of the CA microsatellite on porcine performance are due to the linkage with the poly(dA:dT) tract.…”