Indirect effect of IGF2 intron3 g.3072G>A mutation on prolificacy in sows.
ABSTRACT A QTL located in the paternally expressed insulin-like growth factor 2 (IGF2) gene is known to increase muscle growth and reduce fat deposition in pigs. This makes the QTL in IGF2 a good marker for use in pig breeding programmes. However, care has to be taken as it is postulated that increased leanness and lowered fat deposition may have a negative effect on the prolificacy and longevity of sows. Selection of sire and dam lines for different alleles of the mutation in the paternally imprinted IGF2 gene could actually provide a solution to this problem. Therefore, in this study, the effect of the IGF2 QTL on prolificacy-related traits in sows was investigated. It was found that the paternal IGF2 wild-type allele was associated with higher reproduction performance in the sow. Moreover, it was also examined whether the difference in prolificacy in sows could be a consequence of differential IGF2 expression in the ovarian follicles of the sow or whether it is mainly a secondary effect caused by differences in fatness traits. Therefore, IGF2 expression was measured in follicles of different sizes from sows with different genotypes for the paternal IGF2 allele. It was observed that, however, while the size of the follicles was associated with follicular IGF2 expression level, the IGF2 genotype was not. It could be concluded that the difference in prolificacy of sows with a different paternal IGF2 genotype could be a secondary effect, resulting from differences in fat deposition.
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ABSTRACT: Porcine reproductive and respiratory syndrome (PRRS) is the most economically significant disease impacting pig production in North America, Europe, and Asia, causing reproductive losses such as increased rates stillbirth and mummified piglets. The objective of this study was to explore the genetic basis of host response to the PRRS virus (PRRSV) in a commercial multiplier sow herd before and after a PRRS outbreak, using antibody response and reproductive traits. Reproductive data comprising number born alive (NBA), number alive at 24h (NA24), number stillborn (NSB), number born mummified (NBM), proportion born dead (PBD), number born dead (NBD), number weaned (NW), and number mortalities through weaning (MW) of 5,227 litters from 1,967 purebred Landrace sows, were used along with a pedigree comprising 2,995 pigs. The PRRS outbreak date was estimated from rolling averages of farrowing traits and used to split the data in a pre-PRRS phase and a PRRS phase. All 641 sows in the herd during the outbreak were blood sampled 46 days after the estimated outbreak date, and were tested for anti-PRRSV IgG using ELISA (sample-to-positive [S/P] ratio). Genetic parameters of traits were estimated separately for the pre-PRRS and PRRS phase data sets. Sows were genotyped using the PorcineSNP60 BeadChip, and genome-wide association studies (GWAS) were performed using method Bayes-B. Heritability estimates for reproductive traits ranged from 0.01 (NBM) to 0.12 (NSB), and from 0.01 (MW) to 0.12 (NBD) for the pre-PRRS and PRRS phases, respectively. S/P ratio had heritability (0.45) and strong genetic correlations with most traits, ranging from -0.72 (NBM) to 0.73 (NBA). In the pre-PRRS phase, regions associated with NSB and PBD explained 1.6% and 3% of the genetic variance, respectively. In the PRRS phase, regions associated with NBD, NSB, and S/P ratio explained 0.8%, 11%, and 50.6% of the genetic variance, respectively. For S/P ratio, two regions on SSC7 separated by 100 Mb explained 40% of the genetic variation, including a region encompassing the Major Histocompatibility Complex, which explained 25% of the genetic variance. These results indicate a significant genomic component associated with PRRSV antibody response and NSB in this dataset. Also, the high heritability and genetic correlation estimates for S/P ratio during the PRRS phase suggest that S/P ratio could be used as an indicator of the impact of PRRS on reproductive traits.Journal of Animal Science 05/2014; · 1.92 Impact Factor
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ABSTRACT: Litter size in pigs is a major factor affecting the profitability in the pig industry. The peri-implantation window in pigs is characterized by the coordinated interactions between the maternal uterine endometrium and the rapidly elongating conceptuses and represents a period of time during which a large percentage of the developing conceptuses are lost. However, the gene expression and regulatory networks in the endometrium contributing to the establishment of the maternal: placental interface remain poorly understood. We characterized the endometrial gene expression profile during the peri-implantation stage of development by comparing two breeds that demonstrate very different reproductive efficiencies. We employed the porcine Affymetrix GeneChip(R) to assay the transcriptomic profiles of genes expressed in the uterine endometrium obtained from Meishan and Yorkshire gilts (n = 4 for each breed) on day 12 of gestation (M12 and Y12, respectively). Total of 17,076 probesets were identified as "present" in at least two arrays. A mixed model-based statistical analysis predicted a total of 2,656 (q < 0.1) transcripts as differentially expressed between Meishan and Yorkshire pigs. Eighteen differentially expressed transcripts of interest were validated by quantitative real-time PCR. Gene ontology (GO) annotation revealed that the known functions of the differentially expressed genes were involved in a series of important biological processes relevant to early pregnancy establishment in the pig. The results identified endometrial gene expression profiles of two breeds differing in litter size and identified candidate genes that are related to known physiological pathways related to reproductive prolificacy. These findings provide a deeper understanding of molecular pathways differing between two breeds at the critical peri-implantation stage of pregnancy, which can be utilized to better understand the events contributing to pregnancy establishment in the pig.BMC Genomics 02/2014; 15(1):156. · 4.04 Impact Factor
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ABSTRACT: In recent years, intensive attention has been put on improving reproductive performance of pigs. Several experiments aimed to identify markers associated with prolificacy, but this issue still remains open. In our study, we investigated associations between polymorphisms in IGF2, GNAS and MC4R genes with reproductive traits of Polish Landrace and Large White pigs. We did not find any significant associations for g. GNAS314T > 324C, IGF2 intron3-g.3072G > A or g. MC4R 1426G > A in Polish Landrace and Large White pigs. In the case of IGF2 intron3-g.3072G > A, this information is of great importance, because this marker is widely implemented in pigs breeding and previous experiments suggested its role in prolificacy of pigs. We also investigated expression of IGF2 gene and showed that this gene is monoallelically expressed in reproductive organs (ovary and cornus uteri).Reproduction in Domestic Animals 11/2012; · 1.18 Impact Factor