Properdin (BF) was investigated as a candidate gene influencing litter size in a commercial pig cross population. The BF gene was chosen because of its integral role in influencing uterine epithelium growth and because several quantitative trait loci (QTL) with impact on reproductive traits have been detected near the centromere of porcine chromosome 7. A total of 123 F2 (Large White x Landrace) x Leicoma sows were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The sows were divided into two extreme performance groups, one with a high litter size (n = 61, > or = 14.3 piglets per litter) and the other with a low litter size (n = 62, < or = 11.3 piglets per litter). Although genotype and allele frequencies were uneven with 2.4% (AA), 16.3% (AB), 81.3% (BB) and 0.11 (A): 0.89 (B), the allele A was the unfavourable one, leading to less offspring. With regard to the level of significance at p < 0.05, the total number of born (TNB) and number of born alive (NBA) piglets were associated with BF genotypes. The genotype AA led to 10.55 TNB and 10.00 NBA, whereas the genotype BB led to 13.19 TNB and 12.11 NBA. The genotype AB was intermediate. In future, a systematic mating test is necessary in order to obtain more balanced genotype frequencies. Furthermore, it should be taken into consideration that the investigated polymorphism is located in an intronic region and the causative mutation is not clear yet.

The aim of this study was to investigate, if special genotypes of the genes glutathione peroxidase 5 (GPX5), fucosyltransferase 1 (FUT1) and estrogen receptor 2 (ESR2) are associated with litter size in a commercial pig cross population. For this purpose, a total of 123 F 2 sows were divided into two extreme performance groups, one with a high litter size (n = 61, ≥ 14.3 piglets per litter) and one with a low litter size (n = 62, ≤ 11.3 piglets per litter) and genotyped using PCR-RFLP methods. The Chi-square test was used in order to investigate, if a special genotype occurs significantly more often in one of the two performance groups (p < 0.05). Whereas no association was found between different ESR2 or GPX5 genotypes with one of the two performance groups, the number of sows with AB genotypes at the FUT1 gene was significantly increased in the high performance group in comparison to the low performance group.

The aim of this study was to estimate the allele frequencies in polymorphic site of exon six of POU1F1 gene in three Iranian native and Holstein cattle. Genomic DNA was extracted from 3 Iranian native cattle breeds, including 97 Mazandarani, 87 Sarabi, 112 Golpaygani and also 110 Holstein cattle. A 451 bp fragment of intron 5 and exon 6 were amplified and digested with HinfI restriction enzyme. Frequencies of allele A were 0.37, 0.27, 0.34 and 0.21 for Mazandarani, Sarabi, Golpaygani and Holstein cattle, respectively. Significant differences in genotype frequencies were found between Mazandarani or Golpaygani and Holstein cattle. No significant differences in genotype frequencies were found between Sarabi and Holstein cattle. Transition A to G in nucleotide 1256 is responsible for HinfI(-) allele. No significant association was observed between POU1F1 polymorphism and milk production. Differences in allelic frequency between native Bos indicus breeds (Mazandarani, Golpaygani) and Holstein at the present study might be due to differences in origin breeds, low number of samples and/or as the effect of natural selection in native breeds.

Abstract. The following steps were performed to analyse heterosis and QTL effects in litter size of mice: intercross of mouse inbred strains C57BL/6J and Balb/cJ in order to produce a F2 generation with 948 female animals; selection of trait groups with extreme high ((13 offspring) and extreme low litter size (5 offspring)); typing of 56 microsatellites with an average distance of 32 cM; detection of different chromosome regions with associations to heterosis in litter size. Chromosome 19 was associated to heterosis in litter size. Additional animals with extreme high and low litter sizes were then typed for four DNA markers on chromosome 19 and used for QTL mapping. A QTL was identified for litter size in segment D19Mit28 &amp;ndash: D19Mit99 with a maximum at 15 cM (p ≤ 0.05). The QTL explains about 11% of the phenotypic variance in the F2 generation. With a degree of dominance of 4.09 the QTL shows that superdominance can explain heterosis in litter size.

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