Previously, we found that a greater dissimilarity in swine leukocyte antigen (SLA) class I and class II alleles between mating partners resulted in increased farrowing rates in a highly inbred population of Microminipigs (MMPs). In this follow-up study, we have analyzed the effects of dissimilarity in SLA alleles between mating partners for seven different reproductive traits, including litter size and the number of stillborn and live or dead weaned piglets. We determined the relationships among reproductive traits within each mating event and the amino acid distances of SLA alleles as markers of diversity between mating partners. Our results indicate that mating partners with greater amino acid pairwise genetic distances in the SLA-1 class I gene or DQB1 class II gene alleles were associated with significantly larger litter sizes and higher numbers of live piglets at birth and weaning. Also, partners with greater pairwise distances in the SLA-2 class I gene alleles exhibited fewer pre-weaning deaths. These findings suggest that the dissimilarity in SLA class I and class II alleles between mating partners may affect not only farrowing rates but also other key reproductive traits such as litter size and improved piglet survival rates. Consequently, SLA alleles could serve as valuable genetic markers for selecting mating partners in breeding programs and for conducting epistatic studies on various reproductive traits in MMPs.

Dynein Axonemal Heavy Chain 1 (DNAH1) encodes proteins which provide structural support for the physiological function and motor structure of spermatozoa (hereafter referred to as sperm) and ova. This study found that three single nucleotide polymorphisms (SNPs), the 27-bp insertion/deletion (InDel) mutations and three exonic copy number variations (CNVs) within DNAH1 were significantly associated with litter size of Shaanbei white cashmere goats (n = 1101). Goats with the wildtypes of these three SNPs had higher litter sizes than other carriers (p < 0.05). II genotype of the 27-bp InDel had the highest litter size compared with ID carriers (p = 0.000022). The gain genotype had the largest litter sizes compared with the loss or medium carriers for the three CNV mutations (p < 0.01). Individuals with the AA-TT-CC-II-M1-M2-M3 and AA-TT-CC-II-G1-G2-M3 combination genotypes had larger litter sizes compared with the other genotypes. This study also showed the DNAH1 expression in mothers of multiple kids was higher than mothers of single kids. These three SNPs, the 27-bp InDel and three CNVs in DNAH1 could be used as molecular markers for the selection of goat reproductive traits.

Several genes are associated with the multiple morphological abnormalities of the sperm flagella (MMAF) syndrome, including QRICH2, CFAP43, CFAP44, CFAP69, CCDC39, and AKAP4 genes. Although previous work has shown that these genes are significantly associated with male reproductive traits in certain species, it is not yet known whether they are associated with reproductive traits in the goat. In this study, we investigated the correlations between 47 putative indel mutations in MMAF- associated genes, and first-born litter sizes in 1479 Shaanbei white cashmere (SBWC) goats. Our analysis showed that five of these indel mutations were polymorphic: QRICH2-P4, CFAP43-P20, CFAP69-P4, CFAP69-P6, and CFAP69-P7. Association analysis revealed that only a 6-bp indel variation within CFAP43 (CFAP43-P20) was strongly significantly associated with litter sizes in SBWC goats (P = 0.000). We also identified a significant difference in the genotypic distribution between the mothers of single lambs and the mothers of multiple lambs (P = 0.001); carriers of the DD genotype had greater litter sizes than carriers of the II or ID genotype. Our analysis also revealed 8-bp and 6-bp indels in CFAP69 (CFAP69-P4 and CFAP69-P6, respectively) that were in complete linkage disequilibrium with each other (D\' = 0.99, r2 = 1.00). These findings indicate that the 6-bp indel mutation in the CFAP43 gene can be used as an effective molecular marker for selecting reproductive traits in goat breeding operations.