Indigenous Pig Research Articles

Indigenous Technical Knowledge and Its Potential Application to Uganda's Pig Sub‐Sector

ABSTRACTUganda's pork consumption is speculated to exceed any other livestock meat consumption by 2050. However, the current trend in pig production may not meet the demand due to pig production constraints such as recurrent disease incidences and high feeding costs. The proposed modern practices are not cost‐effective, especially for resource‐constrained pig farmers. This review, therefore, synthesises previous studies on the practicability of integrating Indigenous Technical Knowledge (ITK) in pig production to mitigate the prevailing pig production challenges in Uganda. By employing ITK, smallholder farmers have realised that indigenous pig breeds are disease‐resistant and suit the prevailing harsh tropical conditions. In addition, affordable plant‐based concoctions have been developed to cure diseases in pigs. For example, Centella asiatica has been identified as a potential purgative for diarrhoeal infections. Integrating pigs in cropping systems has also been adopted as a low‐cost alternative to effectively feed pigs for optimal performance. Fortunately, most of the ITK options for solving pig production challenges are feasible in Uganda. Thus, ITK should be embedded in the country's extension system to increase smallholder farmers' awareness about its potential of improving pig production. An ITK‐modern technology integration would probably meet the acceptance and be suitable for commercial pig producers.

Genomic Insights into Pig Domestication and Adaptation: An Integrated Approach Using Genome-Wide Selection Analysis and Multiple Public Datasets.

As a global focus of animal husbandry, pigs provide essential meat resources for humans. Therefore, analyzing the genetic basis of adaptability, domestication, and artificial selection in pigs will contribute to further breeding. This study performed a genome-wide selection sweep analysis to identify candidate genes related to domestication and adaptive selection via data from 2413 public genotypes. Two complementary statistical analyses, FST (fixation index) and XP-EHH (cross-population extended haplotype homozygosity) were applied. The results revealed that numerous candidate genes were associated with high-altitude adaptability (e.g., SIRPA, FRS2, and GRIN2B) and habitat temperature adaptability (e.g., MITF, PI3KC2A, and FRS2). In addition, candidate genes related to the domestic genetic imprint of indigenous pigs (e.g., TNR, NOCT, and SPATA5) and strong artificial selection pressure in commercial breeds (e.g., ITPR2, HSD17B12, and UGP2) were identified in this study. Specifically, some MHC-related genes (e.g., ZRTB12, TRIM26, and C7H6orf15) were also under selection during domestication and artificial selection. Additionally, a phylogenetic comparative analysis revealed that the genetic divergence between populations does not fully follow the geographical distribution and management history in the major histocompatibility complex region/major histocompatibility complex II haplotypes, unlike that of the genome-wide genotypes. Furthermore, the higher heterozygosity and haplotype alleles of MHC reduce the differences between populations. Briefly, this study not only helps promote the relative theoretical understanding of environmental adaptive selection and domestication but also provides a theoretical reference for disease-resistant breeding in pigs.

Population Structure and Selection Signatures in Chinese Indigenous Zhaotong Pigs Revealed by Whole-Genome Resequencing.

Zhaotong pig (ZTP) is a Chinese indigenous pig breed in Yunnan Province, known for its unique body shape and appearance, good meat quality, strong foraging ability, and adaptability. However, there is still a lack of research on its genome. In order to investigate the genetic diversity, population structure, and selection signatures of the breed, we conducted a comprehensive analysis by resequencing on 30 ZTPs and comparing them with genomic data from 10 Asian wild boars (AWBs). A total of 45,514,452 autosomal SNPs were detected in the 40 pigs, and 23,649,650 SNPs were retained for further analysis after filtering. The HE, HO, PN, MAF, π, and Fis values were calculated to evaluate the genetic diversity, and the results showed that ZTPs had higher genetic diversity and lower inbreeding coefficient compared with AWBs. Population structure was analyzed using NJ tree, PCA, ADMIXTURE, and LD methods. It was found that ZTPs were population independent of AWBs and had a lower LD decay compared to AWBs. Moreover, the results of the IBS genetic distance and G matrix showed that most of the individuals had large genetic distances and distant genetic relationships in ZTPs. Selection signatures were detected between ZTPs and AWBs by using two methods, FST and π ratio. Totals of 1104 selected regions and 275 candidate genes were identified. Finally, functional enrichment analysis identified some annotated genes that might affect fat deposition (NPY1R, NPY5R, and NMU), reproduction (COL3A1, COL5A2, GLRB, TAC3, and MAP3K12), growth (STAT6 and SQOR), tooth development (AMBN, ENAM, and ODAM), and immune response (MBL2, IL1A, and DNAJA3). Our results will provide a valuable basis for the future effective protection, breeding, and utilization of ZTPs.

Integrated analysis of muscle lncRNA and mRNA of Chinese indigenous breed Ningxiang pig in four developmental stages.

Meat and its derivatives serve as crucial sources of protein, vitamins, minerals, and other essential nutrients for humans. Pork stands as China's primary animal-derived food product consumed widely across diverse dietary structures; evaluating intramuscular fat content becomes pivotal in assessing its quality standards. Nonetheless, the intricate molecular mechanisms governing intramuscular fat deposition remain elusive. Our study utilized sequencing technology to scrutinize longitudinal development stages within Ningxiang pig's longest dorsal muscles aiming to unravel these underlying mechanisms. In three distinct comparisons (30d vs. 90d, 90d vs. 150d and 150d vs. 210d) there were 578, 1,000 and 3,238 differentially expressed mRNA, along with 16, 158 and 85 lncRNAs were identified. STEM analysis unveiled six enriched model profiles for lncRNAs while seven such profiles emerged for mRNAs; notably, multiple shared model profiles existed between both RNA types. Enriched analysis highlighted numerous genes from mRNA profile8 and lncRNA profile7 significantly associated with pathways linked to fat deposition. Weight Gene Co-Expression Network Analysis (WGCNA) revealed that differential expression modules (DMEs) & differential expression lncRNAs primarily clustered within cyan, dark slate blue and pale turquoise modules. Furthermore, target genes PKD2 (MSTRG21592.MTRSG8859 and MTRSG18175), COL5A1 (MTRSG9969 and MTRSG180) and SOX13 (MTRSG21592 and MTRSG9088) as core components all intricately tied into processes related to fat deposition. This study lays the groundwork for deeper exploration into the molecular mechanisms underlying LDM fat deposition traits, and it also presents candidate genes for future molecular marker-assisted breeding.

Genome-Wide Analysis Reveals Copy Number Variant Gene TGFBR3 Regulates Pig Back Fat Deposition.

BFT is closely related to meat quality and lean meat percentage in pigs. The BFT traits of European LW pigs significantly differ from those of Chinese indigenous fatty MZ pigs. CNV is a prevalent genetic variation that plays an important role in economically important traits in pigs. However, the potential contribution of CNV to BFT in LW and MZ pigs remains unclear. In this study, whole-genome CNV detection was performed using next-generation sequencing data from LW and MZ pigs, and transcriptome data from back fat tissue of 180-day-old LW and MZ pigs were integrated for expression quantitative trait loci (eQTL) analysis. We identified a copy number variation in the TGFBR3 gene associated with BFT, showing a dose effect between the genome and transcriptome levels of the TGFBR3 gene. In porcine preadipocytes, TGFBR3 expression continuously increased during differentiation. Knockdown of TGFBR3 using specific siRNA inhibited preadipocyte differentiation and proliferation. Our study provides insights into the genetic regulation of pork quality and offers a theoretical basis for improving carcass quality by modulating BFT in pigs.

Analysis of the Genetic Diversity and Genetic Structure of Jiangshan Black Pigs Using Single Nucleotide Polymorphism (SNP) Chips.

The Jiangshan black pig is an indigenous pig breed in China, renowned for its superior meat quality and adaptability to roughage. However, the population of Jiangshan black pigs has dwindled due to the introduction of cosmopolitan pig breeds and the outbreak of African swine fever, putting them at risk of extinction. To offer insights into the conservation and breeding of Jiangshan black pigs, this study involved 118 Jiangshan black pigs as the research subjects and employed the Zhongxin-1 Porcine Breeding Array PLUS chip to detect whole-genome SNPs. Additionally, various software tools were utilized to accurately analyze the genetic diversity, phylogenetic relationship, inbreeding coefficient, and pedigree structure of the Jiangshan black pig conservation population. The findings indicated that the effective population size (Ne) of the Jiangshan black pig was 4.9, with an average inbreeding coefficient of 0.253 within the population. A genetic relationship analysis identified that the 16 male pigs were clustered into four families, and the 100 female pigs were also assigned to these familial groups. Furthermore, two female pigs were classified as "other" due to their distant genetic relatedness to all the males. These results contribute to a better understanding of the current status of the conservation of the Jiangshan black pig population and offer a theoretical foundation for the development of conservation strategies.

Comparative characterization of fatty acids and volatile substances in Chinese indigenous and hybrid pork in raw, cooked, and reheated states

Fatty acids and volatile substances in hybrid pork (Duroc × Landrace × Yorkshire; DLY) and four indigenous pork (Guangdong small-ear spotted; hill black; Beijing black, BB; and Qingyu) in raw, cooked, and reheated states were explored. The objectives were to determine odor differences between DLY and indigenous pork and the difference in changes after heating and reheating and to clarify the reasons for these changes. Results revealed that C18:1 and C20:4 fatty acids are the key to distinguishing DLY pork from indigenous pork. After cooking, the greatest decrease was observed in the proportion of polyunsaturated fatty acids in pork, and after reheating, monounsaturated fatty acids were detected, except in the BB pork. The substances that accounted for the difference between DLY and indigenous pork were 2,3-octadione, hexanal, 1-octen-3-ol, 2-nonanone (after heating), and (Z)-2-nonenal (after reheating). Reheating reduced the content of nonanal, 2,3-octandione, hexanal, and (E,E)-2,4-decadienal, resulting in the deterioration of the aroma. In the DLY pork, the dramatic increase in the (Z)-2-nonenal content may be the key factor. Principal component analysis identified that the difference in aroma between DLY and indigenous pork increased after reheating, but hierarchical cluster analysis showed that regardless of treatment, flavor difference was smaller between DLY and indigenous pork than among indigenous pigs. The analysis results show that differences in fatty acid content and oxidation path in unsaturated fatty acids were the reasons for the difference in aroma and the deterioration of flavor after reheating.

Effects of Repeatability and Heritability Growth Traits on Indigenous Guinea Pigs in Nigeria

Effects of Repeatability and Heritability Growth Traits on Indigenous Guinea Pigs in Nigeria

Characterization of Meat Metabolites and Lipids in Shanghai Local Pig Breeds Revealed by LC-MS-Based Method.

The meat of local livestock breeds often has unique qualities and flavors. In this study, three Shanghai native pig breeds (MSZ, SWT, and SHB) exhibited better meat quality traits than globalized commercial pig breeds (DLY). Subsequently, metabolomic and lipidomic differences in the longissimus dorsi (L) and gluteus (T) muscles of the Shanghai native pig breeds and DLY pig breed were compared using liquid chromatography-mass spectrometry (LC-MS). The results demonstrated that the metabolites mainly consisted of (28.16%) lipids and lipid-like molecules, and (25.87%) organic acids and their derivatives were the two most dominant groups. Hundreds of differential expression metabolites were identified in every compared group, respectively. One-way ANOVA was applied to test the significance between multiple groups. Among the 20 most abundant differential metabolites, L-carnitine was significantly different in the muscles of the four pig breeds (p-value = 7.322 × 10-11). It was significantly higher in the L and T muscles of the two indigenous black pig breeds (MSZ and SWT) than in the DLY pigs (p-value < 0.001). Similarly, lipidomic analysis revealed the PA (18:0/18:2) was significantly more abundant in the muscle of these two black breeds than that in the DLY breed (p-value < 0.001). These specific metabolites and lipids might influence the meat quality and taste properties and lead to customer preferences. Therefore, this study provided insights into the characterization of meat metabolites and lipids in Shanghai native pig breeds.

The Adaptive Alternation of Intestinal Microbiota and Regulation of Host Genes Jointly Promote Pigs to Digest Appropriate High-Fiber Diets.

Although studies have revealed the significant impact of dietary fiber on growth performance and nutrient digestibility, the specific characteristics of the intestinal microbiota and gene regulation in pigs capable of digesting high-fiber diets remained unclear. To investigate the traits associated with roughage tolerance in the Chinese indigenous pig breed, we conducted comparative analysis of growth performance, apparent fiber digestibility, intestinal microbiota, SCFA concentrations and intestinal transcriptome in Tunchang pigs, feeding them diets with different wheat bran levels. The results indicated that the growth performance of Tunchang pigs was not significantly impacted, and the apparent total tract digestibility of crude fiber was significantly improved with increasing dietary fiber content. High-fiber diets altered the diversity of intestinal microbiota, and increased the relative abundance of Prevotella, CF231, as well as the concentrations of isobutyrate, valerate and isovalerate. The LDA analysis identified potential microbial biomarkers that could be associated with roughage tolerance, such as Prevotella stercorea, and Eubacterium biforme. In addition, appropriate high-fiber diets containing 4.34% crude fiber upregulated the mRNA expressions of PYY, AQP8, and SLC5A8, while downregulating the mRNA expressions of CKM and CNN1.This indicated that appropriate high-fiber diets may inhibit intestine motility and increase the absorption of water and SCFAs.

The Influence of Increasing Roughage Content in the Diet on the Growth Performance and Intestinal Flora of Jinwu and Duroc × Landrace × Yorkshire Pigs.

The Jinwu pig (JW) is a hybrid breed originating from the Chinese indigenous Jinhua pig and Duroc pig, boasting excellent meat quality and fast growth rates. This study aimed to verify the tolerance of JW to roughage, similar to most Chinese indigenous pigs. In this research, two types of feed were provided to JW and Duroc × Landrace × Yorkshire pigs (DLY): a basal diet and a roughage diet (increasing the rice bran and wheat bran content in the basal diet from 23% to 40%) for a 65-day experimental period. The roughage diet showed an increasing trend in the feed conversion ratio (F/G), with a 17.61% increase in feed consumption per unit weight gain for DLY, while the increase for JW was only 4.26%. A 16S rRNA sequencing analysis revealed that the roughage diet increased the relative abundance of beneficial bacteria, such as Lactobacillus and Clostridium, while reducing the relative abundance of some potential pathogens, thus improving the gut microbiota environment. After being fed with the roughage diet, the abundance of bacterial genera, such as Treponema, Terrisporobacter, Coprococcus, and Ruminococcaceae, which aid in the digestion and utilization of dietary fiber, were significantly higher in Jinwu compared to DLY, indicating that these bacterial genera confer Jinwu with a higher tolerance to roughage than DLY.

Characterization of an African swine fever virus outbreak in India and comparative analysis of immune genes in infected and surviving crossbreed vs. indigenous Doom pigs.

Since 2020, African swine fever (ASF) has affected all pig breeds in Northeast India except Doom pigs, a unique indigenous breed from Assam and the closest relatives of Indian wild pigs. ASF outbreaks result in significant economic losses for pig farmers in the region. Based on sequencing and phylogenetic analysis of the B646L (p72) gene, it has been determined that ASFV genotype II is responsible for outbreaks in this region. Recent studies have shown that MYD88, LDHB, and IFIT1, which are important genes of the immune system, are involved in the pathogenesis of ASFV. The differential expression patterns of these genes in surviving ASFV-infected and healthy Doom breed pigs were compared to healthy controls at different stages of infection. The ability of Doom pigs to withstand common pig diseases, along with their genetic resemblance to wild pigs, make them ideal candidates for studying tolerance to ASFV infection. In the present study, we investigated the natural resistance to ASF in Doom pigs from an endemic area in Northeast India. The results of this study provide important molecular insights into the regulation of ASFV tolerance genes.

Assessment of the digestibility, growth performance, hematological and serum biochemical profile of Bandjock Local Pigs (BLP) and Duroc X Large White pigs (DLW)

The study aimed to assess the digestibility, growth performance, and selected biochemical and hematological parameters of Bandjock Local pigs (BLP) and Duroc X Large White pigs (DLW). We hypothesize that the use of local ingredients in diet formulation associated to improved rearing conditions, enhance the growth performance, digestibility, biochemical and hematological parameters of BLP. The trial involved dividing twenty-four eight-week-old weaner pigs into two groups. Each group was randomly assigned to separate pig units. Animal management and feeding were consistent between both groups. The trial lasted for 120 days during which the growth performance, the digestibility of ingested nutrients, and biochemical and hematological parameters were evaluated. The results indicate that DLW pigs registered a weight gain (46.56±5.19 kg) significantly higher than BLP pigs (34.02), with a statistically similar feed conversion ratio. Except for albumin which was significantly higher in DLW and urea in BLP, there were no significant differences (p > 0.05) in total protein, cholesterol, globulin, triglycerides, creatinine, AST, and ALT as well as hematological parameters between the breeds. However, the exotic DLW had a relatively high mean blood platelets and white blood cell concentration. Although the fecal nitrogen was higher in BLP and the urinary nitrogen was lower in the DLW, there were significant differences (p < 0.05) for urine, fecal, and total excreted nitrogen in both breeds. The lowest scores in nutrient digestibility were recorded with BLP compared to DWL, except for crude fibers. The results of this study demonstrated that using diet formulated with local ingredients and improved rearing conditions, Cameroonian local indigenous pigs have a better productivity compared to exotic breeds. It suggests that efforts should be made by authorities to promote and valorize the rearing of indigenous pigs in complement to exotic pig breeds in view of strengthening the Cameroonian pig industry.

Comprehensive characterization of the differences in metabolites, lipids, and volatile flavor compounds between Ningxiang and Berkshire pigs using multi-omics techniques

This study was conducted to comprehensively characterize, metabolites, lipids, and volatile flavor compounds of NingXiang (NX) pigs, Berkshire (BKS) pigs, and their crossbred (Berkshire × Ningxiang, BN) pigs using multi-omics technique. The results showed that NX had high intramuscular fat (IMF) content and meat redness. The metabolite and lipid compositions were varied greatly among three pig breeds. The NX pigs exhibited distinctive sweet, fruity, and floral aroma while BN pigs have inherited this flavor profile. 2-pentylfuran, pentanal, 2-(E)-octenal, and acetic acid were the key volatile flavor compounds (VOC) of NX and BKS pork. The VOCs were influenced by the composition and content of metabolites and lipids. The NX pigs have excellent meat quality traits, unique flavor profiles, and high degree of genetic stability regarding flavor. The study deepens our understanding of the flavor of Chinese indigenous pigs, providing theoretical basis to understand the meat flavor regulation under different feeding conditions.

Integrating Multiple Database Resources to Elucidate the Gene Flow in Southeast Asian Pig Populations.

The domestic pig (Sus scrofa) and its subfamilies have experienced long-term and extensive gene flow, particularly in Southeast Asia. Here, we analyzed 236 pigs, focusing on Yunnan indigenous, European commercial, East Asian, and Southeast Asian breeds, using the Pig Genomics Reference Panel (PGRP v1) of Pig Genotype-Tissue Expression (PigGTEx) to investigate gene flow and associated complex traits by integrating multiple database resources. In this study, we discovered evidence of admixtures from European pigs into the genome of Yunnan indigenous pigs. Additionally, we hypothesized that a potential conceptual gene flow route that may have contributed to the genetic composition of the Diannan small-ear pig is a gene exchange from the Vietnamese pig. Based on the most stringent gene introgression scan using the fd statistic, we identified three specific loci on chromosome 8, ranging from 51.65 to 52.45 Mb, which exhibited strong signatures of selection and harbored the NAF1, NPY1R, and NPY5R genes. These genes are associated with complex traits, such as fat mass, immunity, and litter weight, in pigs, as supported by multiple bio-functionalization databases. We utilized multiple databases to explore the potential dynamics of genetic exchange in Southeast Asian pig populations and elucidated specific gene functionalities.

Single-Nucleus RNA-Seq Reveals Spermatogonial Stem Cell Developmental Pattern in Shaziling Pigs.

Normal testicular development ensures the process of spermatogenesis, which is a complex biological process. The sustained high productivity of spermatogenesis throughout life is predominantly attributable to the constant proliferation and differentiation of spermatogonial stem cells (SSCs). The self-renewal and differentiation processes of SSCs are strictly regulated by the SSC niche. Therefore, understanding the developmental pattern of SSCs is crucial for spermatogenesis. The Shaziling pig is a medium-sized indigenous pig breed originating from central China. It is renowned for its superior meat quality and early male sexual maturity. The spermatogenic ability of the boars is of great economic importance to the pig industry. To investigate testicular development, particularly the pattern of SSC development in Shaziling pigs, we used single-cell transcriptomics to identify gene expression patterns in 82,027 individual cells from nine Shaziling pig testes at three key postnatal developmental stages. We generated an unbiased cell developmental atlas of Shaziling pig testicular tissues. We elucidated the complex processes involved in the development of SSCs within their niche in the Shaziling pig. Specifically, we identified potential marker genes and cellular signaling pathways that regulate SSC self-renewal and maintenance. Additionally, we proposed potential novel marker genes for SSCs that could be used for SSC isolation and sorting in Shaziling pigs. Furthermore, by immunofluorescence staining of testicular tissues of different developmental ages using marker proteins (UCHL1 and KIT), the developmental pattern of the spermatogonia of Shaziling pigs was intensively studied. Our research enhances the comprehension of the development of SSCs and provides a valuable reference for breeding Shaziling pigs.

Integrated analysis of muscle transcriptome, miRNA, and proteome of Chinese indigenous breed Ningxiang pig in three developmental stages.

The Ningxiang pig, a distinguished local breed in China, is recognized for its good meat quality traits. This study examines the proteomics of Ningxiang pigs at three developmental stages and delves into the upstream transcriptomics of these proteomics. Such an analysis facilitates a deeper understanding of the molecular interplay between proteins and transcriptomes in the Ningxiang pig muscle, influencing muscle growth and development. In this research, we analyzed the muscles of Ningxiang pigs at three developmental stages: 30days in weaned piglets, 90days in nursery pigs, and 210days in late fattening pigs. There a total of 16 differentially co-expressed miRNAs (ssc-miRNA-1, ssc-miRNA-378, ssc-miRNA-143, ssc-miRNA-30e, etc.), 74 differentially co-expressed mRNA (PLIN3, CPT2, IGF2 and HSP90AB1, etc.) have been identified in the three stages. 572 differentially abundant proteins (DAPs) (APOC3, NDUFA2, HSPD1, ATP5E, PDHA1, etc.) were readily identified by comparing different time periods. According to the KEGG enrich pathway results that DAPs most enriched in growth and development pathways, immune mechanism pathways and maintaining functions of physical. Through short time-series expression miner (STEM) association analysis, a total of 571 negative miRNA-mRNA interaction pairs and 2 negative miRNA-mRNA-protein (Chr05_11955-Pig.17268.1-ATP5F1B, ssc-miR-194a-3p-Pig.15802.1-ACY1) interaction pairs were found. Our study provides a theoretical basis on molecular mechanism for the study of IMF deposition, muscle growth and immunity in Ningxiang pig breed.

Lipopolysaccharide Stimulation of Peripheral Blood Mononuclear Cells of Indigenous Pigs Causes Enhanced Expression of Pro-inflammatory Cytokines Over Exotic Pigs

Background: Selective breeding in pigs based on a higher potential of disease resistance can be achieved by studying the association between immune responsiveness and susceptibility to infectious diseases. The early immune responsiveness of pigs assessed in a quantifiable scale for different determinant cytokine genes’ expression involved in regulation of immune response can be a major determinant for evaluating the immune responsiveness. Methods: In this study, we carried out the quantitative relative expression of candidate cytokine genes [Interleukin-1 beta-(IL1b), IL6, IL10 and tumor necrosis factor-alpha (TNFa) and toll-like receptor-4 (TLR4) gene expression in the lipopolysaccharide (LPS) stimulated peripheral blood mononuclear cells (PBMCs) of Zovawk (indigenous) and Large White Yorkshire (LWY-exotic) pig breeds using real-time PCR to understand the differences in swift immune responsiveness against gram-negative bacteria. Results: Zovawk PBMCs’ pro-inflammatory cytokines IL1b and IL6 expression increased rapidly with LPS stimulation up to 12 h, being significantly higher as early as 4 h compared to that of the LWY PBMCs. In Zovawk pigs, the pro-inflammatory cytokine genes’ expression was found to be quick and high; whereas, in LWY pigs the response was slow and low. Interestingly, the expression of IL10 was not detected in LPS-stimulated PBMCs of Zovawk pigs indicating that the remarkably higher expressions of IL6 and IL1b in response to LPS are within the threshold of the Zovawk pigs which have evolved through generations. Our findings clearly indicate the sturdy and early immune responsiveness of indigenous pigs against gram-negative bacteria over the exotic pigs.

Exploration of Genome-Wide Recombination Rate Variation Patterns at Different Scales in Pigs.

Meiotic recombination is a prevalent process in eukaryotic sexual reproduction organisms that plays key roles in genetic diversity, breed selection, and species evolution. However, the recombination events differ across breeds and even within breeds. In this study, we initially computed large-scale population recombination rates of both sexes using approximately 52 K SNP genotypes in a total of 3279 pigs from four different Chinese and Western breeds. We then constructed a high-resolution historical recombination map using approximately 16 million SNPs from a sample of unrelated individuals. Comparative analysis of porcine recombination events from different breeds and at different resolutions revealed the following observations: Firstly, the 1Mb-scale pig recombination maps of the same sex are moderately conserved among different breeds, with the similarity of recombination events between Western pigs and Chinese indigenous pigs being lower than within their respective groups. Secondly, we identified 3861 recombination hotspots in the genome and observed medium- to high-level correlation between historical recombination rates (0.542~0.683) and estimates of meiotic recombination rates. Third, we observed that recombination hotspots are significantly far from the transcription start sites of pig genes, and the silico-predicted PRDM9 zinc finger domain DNA recognition motif is significantly enriched in the regions of recombination hotspots compared to recombination coldspots, highlighting the potential role of PRDM9 in regulating recombination hotspots in pigs. Our study analyzed the variation patterns of the pig recombination map at broad and fine scales, providing a valuable reference for genomic selection breeding and laying a crucial foundation for further understanding the molecular mechanisms of pig genome recombination.

Resistance to African swine fever virus among African domestic pigs appears to be associated with a distinct polymorphic signature in the RelA gene and upregulation of RelA transcription

African swine fever virus (ASFV) is a highly contagious and fatal hemorrhagic disease of domestic pigs, which poses a major threat to the swine industry worldwide. Studies have shown that indigenous African pigs tolerate ASFV infection better than European pigs. The porcine v-rel avian reticuloendotheliosis viral oncogene homolog A (RelA) encoding a p65 kD protein, a major subunit of the NF-kB transcription factor, plays important roles in controlling both innate and adaptive immunity during infection with ASFV. In the present study, RelA genes from ASFV-surviving and symptomatic pigs were sequenced and found to contain polymorphisms revealing two discrete RelA amino acid sequences. One was found in the surviving pigs, and the other in symptomatic pigs. In total, 16 nonsynonymous SNPs (nsSNPs) resulting in codon changes were identified using bioinformatics software (SIFT and Polyphen v2) and web-based tools (MutPre and PredictSNP). Seven nsSNPs (P374-S, T448-S, P462-R, V464-P, Q478-H, L495-E, and P499-Q) were predicted to alter RelA protein function and stability, while 5 of these (P374-S, T448-S, P462-R, L495-E, and Q499-P) were predicted as disease-related SNPs.Additionally, the inflammatory cytokine levels of IFN-α, IL-10, and TNF-α at both the protein and the mRNA transcript levels were measured using ELISA and Real-Time PCR, respectively. The resulting data was used in correlation analysis to assess the association between cytokine levels and the RelA gene expression. Higher levels of IFN-α and detectable levels of IL-10 protein and RelA mRNA were observed in surviving pigs compared to healthy (non-infected). A positive correlation of IFN-α cytokine levels with RelA mRNA expression was also obtained. In conclusion, 7 polymorphic events in the coding region of the RelA gene may contribute to the tolerance of ASFV in pigs.