To address the safety problems posed by the transportation of boar semen using LN, this study was conducted on the short-term storage of frozen boar semen in dry ice (−79 °C). Boar semen frozen in LN was transferred to dry ice, kept for 1 day, 3 days, 5 days, 7 days, or 8 days, and then moved back to LN. The quality of frozen semen stored in LN or dry ice was determined to evaluate the feasibility of short-distance transportation with dry ice. The results showed that 60 °C for 8 s was the best condition for thawing frozen semen stored in dry ice. No significant differences in spermatozoa motility, plasma membrane integrity, or acrosome integrity were observed in semen after short-term storage in dry ice compared to LN (p > 0.05). There were no significant changes in antioxidant properties between storage groups either (p > 0.05). In conclusion, dry ice could be used as a cold source for the short-term transportation of frozen boar semen for at least 7 days, without affecting sperm motility, morphological integrity, or antioxidant indices.

There are many applications of soybean lecithin (SL) and cholesterol-loaded cyclodextrin (CLC) in sperm freezing processes. To the best of our knowledge, there have been few cases of the combined use of SL and CLC in freezing rooster semen. We investigated the effects of CLC, SL, and their combination on rooster sperm cryodamage. Three experiments were conducted: experiment 1, SL (0.5%, 1%, 1.5%, 2.0%); experiment 2, CLC (1.25 mg, 2.5 mg, 5 mg, 10 mg, 15 mg); and experiment 3, CLC + SL (2.5 mg + 0.25%, 2.5 mg + 0.5%, 2.5 mg + 1%, 2.5 mg + 1.5%). Semen samples were cryopreserved using a programmed cryostat, followed by the determination of post-thaw sperm quality, antioxidant indices, and hatching. The results showed that the combination of 2.5 mg CLC + 0.5% SL had the most significant synergistic effect on cryodamage, and the viability (56.69%), motility (54.35%), mitochondrial activity (54.23%), plasma membrane integrity (53.52%), acrosome integrity (54.71%), and antioxidant activity (MDA concentration: 5.65 nmol/mL; SOD activity: 152.73 U/mL) were significantly greater than those of the other combinations (p < 0.05). Nevertheless, the combined CLC and SL addition group did not substantially increase the fertilization and hatching rates of frozen semen compared with the addition of 2.5 mg CLC. In conclusion, the addition of 2.5 mg CLC and 2.5 mg CLC + 0.5% SL enhanced the quality and fertility of frozen rooster sperm.

This study developed a 60K single-nucleotide polymorphism (SNP) liquid-phase chip (‘Shenxin I’) based on genotyping by target sequencing (GBTS) technology. The chip was used to genotype 1451 individuals spanning five conserved local pig breeds: Fengjing (FJ), Meishan (MMS), Pudong White (PD), Shaowutou (SW), and Shanghai White (SHW), and newborn purebred Meishan offspring (MMS_New). The study assessed the genetic diversity, population structure, and genomic breed composition (GBC) of these breeds. The GBC analysis provided insights into genomic introgression within admixed individuals. Results indicate that PD and FJ breeds exhibited the higher fraction of the genome covered by runs of homozygosity (F_ROH) and slower linkage disequilibrium (LD) decay rate, suggesting higher genetic inbreeding level in these two breeds. The study conducted genetic distance of identity-by-state (IBS) analysis and molecular pedigree construction for the MMS population. Subsequently, purebred mating was implemented by selecting boars from different pedigrees to mate with sows and excluding individuals with high inbreeding coefficients from the breeding program. This resulted in a significant reduction in the overall inbreeding level of the born progeny and an increase in genetic diversity compared to the original population. Consequently, the study concludes that utilizing liquid-phase chip technology for genotyping, constructing molecular pedigrees, and optimizing mating combinations in small populations of locally conserved pig breeds contributes to enhancing the conservation effectiveness.

Background: High lipid accumulation limits the cryotolerance of porcine embryos. This study aimed to identify lipid-lowering combinations during in vivo porcine morulae developing into blastocysts and evaluates their effects on post-warming embryonic development and embryo transfer (ET) pregnancy. Methods: A stable method of in vivo embryo production was established in Meishan pigs to obtain morulae. Morulae were treated with bezafibrate and cholic acid alone, in combination, or with either compound replaced by L-carnitine or niacin, respectively. Treated embryos were vitrified-warmed, followed by determinations of lipid content, cell division and ET. Results: The protocol achieved 95.00% synchronization, with 22.61 embryos obtained per sow in Meishan pigs. The combination of 50 μM of bezafibrate and 50 μM of cholic acid was identified as the optimal non-toxic treatment and produced the lowest lipid droplet content (p < 0.05), indicating a synergistic lipid-lowering effect. This treatment improved post-warming embryonic division (p < 0.05) and was associated with a numerically higher pregnancy rate after ET (71.43% vs. 50.00%). However, 200 μM of this combination impaired blastocyst formation and delayed post-warming embryonic development. Conclusions: Bezafibrate combined with cholic acid reduced embryonic lipid contents and improved cryotolerance, providing a practical strategy for porcine embryo cryopreservation.

This study combined liquid-phase chip technology with a genome-wide association study (GWAS) to identify candidate functional genes for litter size in Meishan pigs. Genotyping of 198 Meishan sows using the “Shenxin No. 1” 60K porcine SNP chip, followed by quality control with PLINK v1.90, yielded 31,430 autosomal SNPs. Principal component analysis revealed no significant population stratification. Using a mixed linear model in GEMMA (v 0.98.1), we identified 9 significant SNP loci and 52 candidate genes on chromosomes 5 and 14, including AEBP2, P2RX2, ANKLE2, PGAM5, and EP400, which are implicated in embryonic development, ovarian function, and cell proliferation. Isolated porcine ovarian granulosa cells were validated by FSHR immunofluorescence, showing 99% purity. Overexpression of AEBP2 significantly upregulated its protein expression (Western blot) and promoted granulosa cell proliferation (CCK-8). Collectively, these results pinpoint potential candidate genomic regions and functional genes associated with litter size and suggest that AEBP2 may enhance reproductive performance by promoting granulosa cell proliferation and follicular development. This provides new targets for elucidating the genetic mechanisms underlying the high fecundity of Meishan pigs and for advancing molecular breeding efforts.