Amphiregulin (AREG), a glycoprotein that is a member of the epidermal growth factor (EGF) family, is expressed by the porcine conceptus and endometrium. AREG genotypes were determined based on an SNP in the intron 3 of the gene. Contradictory effects of AREG genotypes on reproductive traits in different pig breeds were reported previously. G allele had undesirable effect on reproductive trait in Meishan breed, while it had favorable effects in Polish Landrace and Large White. We determined AREG genotypes of 179 pigs including the Duroc, Landrace, Yorkshire, Korean native pig (KNP), and Meishan breeds. Two new SNPs were identified near the previously reported SNP in the intron 3 of AREG. Frequencies of AREG alleles among the Duroc, Landrace, Yorkshire, and KNP sows were significantly different (p<0.001), indicating association between AREG genotypes and pig breeds. The first parity litter size was significantly affected by the breeds (p=0.014), but not by AREG genotypes (p=0.148). However, there were breed and AREG genotype associated trends in the first parity litter size. The first parity litter size appeared to be higher in Duroc and KNP sows with G allele, while it appeared to be lower in Landrace sows with G allele. Significant variability of AREG alleles among pig breeds, for the first time in Duroc and KNP sows, was identified. AREG genotypes may influence reproductive traits differentially for each breed and thus, AREG genotypes may need to be considered when sows are bred to increase litter size.

INTRODUCTION
 MATERIALS AND METHODS
  1. Experimental Animals and Primer Design
  2. PCR Amplification, SNP Identification and Genotyping
  3. Data Analysis
 RESULTS
  1. AREG Genotypes and Sequence Variation
  2. AREG Allele Frequencies, Genotypes and First Parity Litter Sizeof Among Pig Breeds
 DISCUSSION
 REFERENCES

• Du-Wan Kim(Swine Science Division, National Institute of Animal Science, RDA, Cheonan 331-801, Republic of Korea)
• Yoon Seok Nam(Department of Animal Sciences, College of Agriculture and Life Science, Institute of Molecular Biology and Genetics,Chonbuk National University, Jeonju 561-756, Republic of Korea)
• Hee-Bok Park(Division of Animal and Dairy Science, College of Agriculture and Life Sciences, Chungnam National University,Daejeon 305-764, Republic of Korea)
• Jong Gug Kim(Department of Animal Sciences, College of Agriculture and Life Science, Institute of Molecular Biology and Genetics,Chonbuk National University, Jeonju 561-756, Republic of Korea) Correspondence