Pig Fat Research Articles

A low-protein soybean-free diet improves carcass traits and meat quality and modulates the colonic microbiota in Daweizi pigs

IntroductionSoybean meal is an excellent protein source and is widely used in pig feed. However, the Americas account for more than 80% of global soybean production, so European and Asia swine production largely depends on soybean imports. The use of safe and functional unconventional feed sources can effectively alleviate worldwide protein shortage problems.MethodsHere, we formulated a low-protein soybean-free diet (LPNS) for growing and fattening pigs using rice, potatoes, tea, and other unconventional feed sources. Thirty-six healthy Daweizi pigs (average body weight 23.60 ± 1.34 kg) were raised under the same conditions and randomly assigned to two dietary treatments: (1) Con group, corn-soybean base meal; (2) LPNS group. When the average weight of pigs in the group reached 85 kg, two pigs per pen were randomly selected and euthanized for collection of the colonic digesta and carcass traits and for meat quality determination.ResultsCompared with the corn-soybean based diet, the LPNS diet decreased the average daily gain (ADG) and feed conversion ratio (FCR) of Daweizi pigs but had a lower cost per kilogram of gain. In addition, the LPNS diet significantly increased leanness and decreased the fat-skin rate and bone rate of Daweizi pigs. The cooking loss of meat decreased, and unsaturated fatty acids such as C22:6 and n−3 PUFA significantly increased in the LPNS group. Moreover, the purine content in the meat substantially decreased with the LPNS diet. The 16S rDNA analysis revealed that the LPNS diet greatly modified the composition of the colonic microbiota community, with a decrease in the Firmicutes/Bacteroidetes ratio and an increase in the abundance of Lactobacillus spp.DiscussionThe use of functional herbs along with a low-protein diet helped to regulate fat and purine metabolism in fatty-type pigs. The LPNS diet formulated with unconventional-feed sources not only helps reduce the feed cost in swine production but also improves the carcass traits and meat quality of pigs, which is more suitable for small-scale pig farming.

Differential Analysis of Fecal SCFAs and Their Contribution to Adipogenesis in UCP1 Knock-In Pigs

This study aimed to investigate the changes in fecal short-chain fatty acids (SCFAs) content in UCP1 knock-in pigs (KI pigs) and their effect on adipogenesis. Fecal samples from five 6-month-old wild-type (WT) and KI pigs were collected for targeted metabolomics and 16s rRNA sequencing analyses to identify differences in SCFAs and gut microbiota that may contribute to regulating fat deposition in pigs. The metabolome of pig fecal samples targeted for an analysis of SCFAs identified seven SCFAs, with caproic acid (except isovaleric acid) being the significantly different one. The results of the fecal 16s rRNA analysis demonstrated a notable reduction in the abundance of Streptococcus spp. in the KI pigs in comparison to the WT pigs, with a statistically significant difference. Correlation analyses demonstrated a statistically significant positive correlation between the abundance of Streptococcus spp. and SCFAs, as well as pig body weight and fatness. It was postulated that the reduction in SCFAs in the intestinal tracts of KI pigs may be associated with a reduction in Streptococcus spp. abundance. Compared to WT pigs, the concentration of fecal SCFAs in KI pigs was significantly reduced, which may be related to the decreased abundance of Streptococcus. The in vitro experiments showed that caproic acid could significantly enhance the differentiation efficiency of porcine SVF cells into mature adipocytes by activating the FFAR4 gene.

Correction: Liu et al. Two-Stage Multimodal Method for Predicting Intramuscular Fat in Pigs. Agriculture 2024, 14, 1843

In the published article [...]

Investigation the Effect of High-Frequency Noise Exposure on Obesity, Food Intake, and Abdominal Visceral Fat in Adult Male Guinea Pigs

Introduction: Obesity and overweight are major global health challenges. One of the bad effects of noise that has been recently expressed is the effect of noise on obesity. This study aimed to investigate the effect of high-frequency noise exposure on obesity, food intake, and abdominal visceral fat in adult male guinea pigs. Material and Methods: The animals in this study were 24 adult male guinea pigs randomly divided into 3 groups (control and two case groups). Each case group was separately exposed to high- frequency white noise with sound pressure levels in 65 dB and 85 dB for 5 days per week in 30 days. The food intake was measured daily. The weight of animals was measured at the start and on days 6, 12, 18, 24, and at the end of exposure period. The abdominal visceral fat was extracted and weighted at the end of the study period. The data were assessed using SPSS V.22 software. Results: ANOVA analysis showed that exposure to high-frequency noise at 65dB and 85dB had a significant effect on weight gain, food intake, and abdominal visceral fat weight (P-value< 0.05) which in the group exposed to the noise with 65 dB was more than other groups. Conclusion: Based on this study, exposure to high-frequency noise may be an effective factor in obesity and increasing abdominal visceral fat. Further studies are needed to investigate the mechanism affecting weight status following noise exposure

Eubacterium siraeum suppresses fat deposition via decreasing the tyrosine-mediated PI3K/AKT signaling pathway in high-fat diet-induced obesity.

Obesity in humans can lead to chronic diseases such as diabetes and cardiovascular disease. Similarly, subcutaneous fat (SCF) in pigs affects feed utilization, and excessive SCF can reduce the feed efficiency of pigs. Therefore, identifying factors that suppress fat deposition is particularly important. Numerous studies have implicated the gut microbiome in pigs' fat deposition, but research into its suppression remains scarce. The Lulai black pig (LL) is a hybrid breed derived from the Laiwu pig (LW) and the Yorkshire pig, with lower levels of SCF compared to the LW. In this study, we focused on these breeds to identify microbiota that regulate fat deposition. The key questions were: Which microbial populations reduce fat in LL pigs compared to LW pigs, and what is the underlying regulatory mechanism? In this study, we identified four different microbial strains, Eubacterium siraeum, Treponema bryantii, Clostridium sp. CAG:413, and Jeotgalibaca dankookensis, prevalent in both LW and LL pigs. Blood metabolome analysis revealed 49 differential metabolites, including tanshinone IIA and royal jelly acid, known for their anti-adipogenic properties. E. siraeum was strongly correlated with these metabolites, and its genes and metabolites were enriched in pathways linked to fatty acid degradation, glycerophospholipid, and glycerolipid metabolism. In vivo mouse experiments confirmed that E. siraeum metabolites curb weight gain, reduce SCF adipocyte size, increase the number of brown adipocytes, and regulate leptin, IL-6, and insulin secretion. Finally, we found that one important pathway through which E. siraeum inhibits fat deposition is by suppressing the phosphorylation of key proteins in the PI3K/AKT signaling pathway through the reduction of tyrosine. We compared LW and LL pigs using fecal metagenomics, metabolomics, and blood metabolomics, identifying E. siraeum as a strain linked to fat deposition. Oral administration experiments in mice demonstrated that E. siraeum effectively inhibits fat accumulation, primarily through the suppression of the PI3K/AKT signaling pathway, a critical regulator of lipid metabolism. These findings provide a valuable theoretical basis for improving pork quality and offer insights relevant to the study of human obesity and related chronic metabolic diseases. Video Abstract.

Two-Stage Multimodal Method for Predicting Intramuscular Fat in Pigs

Intramuscular fat (IMF) content significantly influences pork tenderness, flavor, and juiciness. Maintaining an optimal IMF range not only enhances nutritional value but also improves the taste of pork products. However, traditional IMF measurement methods are often invasive and time-consuming. Ultrasound imaging technology offers a non-destructive solution capable of predicting IMF content and assessing backfat thickness as well as longissimus dorsi muscle area size. A two-stage multimodal network model was developed in this study. First, using B-mode ultrasound images, we employed the UNetPlus segmentation network to accurately delineate the longissimus dorsi muscle area. Subsequently, we integrated data on backfat thickness and longissimus dorsi muscle area to create a multimodal input for IMF content prediction using our model. The results indicate that UNetPlus achieves a 94.17% mean Intersection over Union (mIoU) for precise longissimus dorsi muscle area segmentation. The multimodal network achieves an R2 of 0.9503 for IMF content prediction, with Spearman and Pearson correlation coefficients of 0.9683 and 0.9756, respectively, all within a compact model size of 4.96 MB. This study underscores the efficacy of combining segmented longissimus dorsi muscle images with data on backfat thickness and muscle area in a two-stage multimodal approach for predicting IMF content.

Performance analysis of biodiesel derived from pork fat of swill and concentrate-fed pigs

With the escalating demand for sustainable energy solutions, unconventional sources are gaining attention, including the utilisation of pork fat for biodiesel production. This study investigates the influence of different pig feeding systems, namely swill and concentrate, on the characteristics and performance of biodiesel derived from pork oil. Twelve Large White Yorkshire piglets were divided into two treatments: one following standard feeding practices (T1), and the other exclusively fed with swill (T2). The pigs were slaughtered, and their fat was processed into biodiesel through transesterification. The fuel properties of the biodiesel were analysed, including kinematic viscosity, flash point, fire point, gross calorific value, and low-temperature fuel properties. Additionally, engine performance and exhaust emissions of a biodiesel blend (B20) derived from pork oil were evaluated and compared to commercial diesel fuel using a Kirloskar single-cylinder diesel engine connected to an eddy current dynamometer. Results indicate that both T1 and T2 B20 biodiesel exhibit favourable characteristics comparable to diesel, with promising fuel density, injection duration, mass flow rate, brake-specific fuel consumption, and brake thermal efficiency across various load conditions. Moreover, critical factors such as cetane number and gross calorific value suggest suitable ignition qualities and energy content, highlighting the potential of pork oil-derived biodiesel as a sustainable alternative fuel source. Keywords: Biodiesel, pork fat, swill, concentrate feeding systems

The Influence of Feeding Type on Quality and Nutritional Characteristics of Pork Fat

The purpose of the study was to analyze the effect of feeding type on selected quality parameters and the nutritional characteristics of pork fat. Fats were extracted by using the modified Folch method from the groin, jowl and trimming shoulder of pigs fed two types of diets: liquid and dry. The peroxide values and fatty acid profiles, as well as their distribution, in the triacylglycerol molecules were determined. Additionally, nutritional indexes and thermal properties, including the oxidative stability of pork fat, were assessed. Among the tested fats, the groin fat was characterized by the best oxidative stability which did not depend on the diet type used. In the case of jowl and trimming shoulder, a higher share of monounsaturated fatty acids was determined in fats of pigs fed a liquid diet, whereas in the groin, jowl and trimming shoulder fats of pigs fed dry feed, a higher share of polyunsaturated fatty acids was found. Fats extracted from the groin, jowl and trimming shoulder of pigs fed a liquid diet showed a more favorable ratio of n-6 to n-3 acids. Despite the different feeding systems used, tested fats were characterized by a similar distribution of fatty acids in triacylglycerol molecules with a positive effect on fat digestibility. It is worth emphasizing that especially in the case of trimming shoulder fat, the influence of a diet used in pigs’ nutrition on quality parameters was noticeable. The trimming shoulder fat of pigs fed a liquid diet was characterized by a longer induction time of oxidation, contained less saturated fatty acids and presented a more favorable fatty acid profile with a beneficial distribution of fatty acids in triacylglycerol molecules.

Identification and functional analysis of a new cold induced LncRNA44154

With the development of high-throughput sequencing technology, numerous unknown long noncoding RNAs (lncRNAs) have been discovered. Preliminary research found that after being subjected to low-temperature enviroment, lncRNA44154 expression in the subcutaneous fat of pigs significantly increased. In order to analyze its biological function and regulatory mechanism, qRT-PCR was used to detect its spatiotemporal expression pattern. The nucleoplasmic isolation and FISH were used to locate it subcellular. Through overexpression or interference assays discussed the effect of lncRNA44154 on adipocyte proliferation and differentiation. RNA-seq was used to screen the biological pathways that lncRNA44154 may be involved in. RNA-pull down was used to find the interaction protein and double luciferase reporter gene detection experiment was used to validate the target gene. It was found that the expression of lncRNA44154 had tissue specificity and played a role in adipocyte proliferation. It was expressed in both cytoplasm and nucleus. After overexpression of lncRNA44154 in adipocytes, the expression level of Cyclins B, D, and E were all up-regulated and the cell proliferation ability was significantly enhanced. The number of positive cells increased significantly and the DNA replication activity was significantly enhanced. LncRNA44154 can promote the proliferation of porcine preadipocytes by encouraging cells to enter the S phase of the cell cycle. The result of interfering with lncRNA44154 is the opposite. Further analysis revealed that lncRNA44154 regulates intracellular lipid metabolism, inhibits the production of intracellular lipid droplets, and inhibits preadipocyte differentiation. RNA-seq results indicate that lncRNA44154 may be involved in biological pathways such as AMPK, PPAR and cAMP signaling pathway. It may work by regulating the RPS4X gene. This research may provide a new perspective for investigating the regulation of adipose metabolism by lncRNAs.

Biodiesel production from agricultural biomass wastes: Duroc breed fat oil, Citrillus lanatus rind, and Sorghum Bagasse

This research study synthesized a base catalyst from the waste Citrullus lanatus rind (WCLR) for the synthesis of biodiesel from the waste pig fat oil. The high-acid-value oil (high free fatty acid: FFA) was converted to low-acid-value oil through adsorption in sorghum bagasse ash with high particle sizes. The developed base catalyst was obtained from the WCLR and was characterized via thermogravimetric analysis (TGA), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD-FT), and Brunauer-Emmett-Teller (BET) adsorption analysis. The properties of biodiesel were compared with the recommended standard.Results reflected that the duroc breed pig fat is rich in oil, and the oil is unsaturated. Sorghum bagasse proved to be a good bio-adsorbent for the unsaturated fat FFA reduction. The catalyst produced from WCLR was found to be rich in potassium-calcium-magnesium (K-Ca-Mg) base salts. The predicted yield of 98.69 % (wt./wt.) at 69.96 min, 79.93 °C, 3.15 % (wt.), and 8.57 (vol.) at desirability of 100 % was validated as 98.52 % (wt./wt.). Catalytic strength can be recycled in five cycles. The cost implications indicated that the cost of producing 25 L of biodiesel is $2.61.This study proved to be the most economical way of producing biodiesel that is environmentally friendly, cost-effective, and easy to produce for future energy needs.•Oil was obtained via rendering from duroc breed waste fat oil.•Sorghum bagasse was used as adsorbent for acid reduction of high FFA pig fat oil.•Base catalyst used was obtained from calcined waste Citrullus lanatus rind.

Epigenomic features associated with body temperature stabilize tissues during cold exposure in cold-resistant pigs

Cold stress in low-temperature environments can trigger changes in gene expression, but epigenomics regulation of temperature stability in vital tissues, including the fat and diencephalon, is still unclear. Here, we explore the cold-induced changes in epigenomic features in the diencephalon and fat tissues of two cold-resistant Chinese pig breeds, Min and Enshi black (ES) pigs, utilizing H3K27ac CUT&Tag, RNA-seq, and selective signature analysis. Our results show significant alterations in H3K27ac modifications in the diencephalon of Min pigs and the fat of ES pigs after cold exposure. Dramatic changes in H3K27ac modifications in the diencephalon of Min pig are primarily associated with genes involved in energy metabolism and hormone regulation, whereas those in the fat of ES pig are primarily associated with immunity-related genes. Moreover, transcription factors PRDM1 and HSF1, which show evidence of selection, are enriched in genomic regions presenting cold-responsive alterations in H3K27ac modification in the Min pig diencephalon and ES pig fat, respectively. Our results indicate the diversity of epigenomic response mechanisms to cold exposure between Min and ES pigs, providing unique epigenetic resources for studies of low-temperature adaptation in large mammals.

THE EFFECT OF COCONUT OIL INTAKE ON THE MEAT FATTY ACID PROFILE OF PIGS

The article deals with the effect of adding coconut oil to the diet of heavy pigs on the concentration of fatty acids in leg meat, back fat, and liver. Lauric acid has several positive effects on the consumer. However, the concentration of this fatty acid in pig meat is very low or absent. Coconut oil, which contains a high concentration of lauric acid, was added to the pigs´ diet (30 g per head per day) for 18 days before slaughtering. This dietary intervention increased the concentration of lauric acid in leg meat and back fat but had no effect on the lauric acid concentration in pig liver. Concentrations of margaric and arachidic acids in leg meat, oleic, arachidic, and sum of mono-unsaturated fatty acids in back fat, palmitoleic and sum of saturated fatty acids in pig liver were affected by the addition of coconut oil to the diet of pigs. The monounsaturation index C18:1/C18:0 in leg meat was higher in the coconut oil group. The intake of small amounts of coconut oil affected the concentration of some fatty acids and increased the concentration of lauric acid in the leg meat and back fat of pigs.

The impact of phenolic compounds on pig fat deposition

The quantity and distribution of fat deposits are crucial factors that impact the quality of pork. Recent studies have indicated that the utilization of natural ingredients plays a significant role in decreasing subcutaneous and visceral fat deposits, as well as enhancing intramuscular fat. Moreover, natural products possess several advantages including being environmentally friendly, safe, free of additives, and leaving no residue. Phenolic compounds derived from fruits, vegetables and herbs constitute of vital component of these natural ingredients. This article examines the influence of phenolic compounds on pig fat deposition, aiming to provide guidance on the utilization of such compounds to regulate fat deposition and enhance pork quality.

Identification of potential tissue-specific biomarkers involved in pig fat deposition through integrated bioinformatics analysis and machine learning

Backfat thickness (BT) and intramuscular fat (IMF) content are closely appertained to meat production and quality in pig production. Deposition in subcutaneous adipose (SA) and IMF concerns different genes and regulatory mechanisms. And larger studies with rigorous design should be carried to explore the molecular regulation of fat deposition in different tissues. The purpose of this study is to gain a better understanding of the molecular mechanisms underlying differences in fat deposition among different tissues and identify tissue-specific genes involved in regulating fat deposition. The SA-associated datasets (GSE122349 and GSE145956) and IMF-associated datasets (GSE165613 and GSE207279) were downloaded from the Gene Expression Omnibus (GEO) as the BT and IMF group, respectively. Subsequently, the Robust Rank Aggregation (RRA) algorithm identified 27 down- and 29 up-regulated differentially expressed genes (DEGs) in the BT group. Based on bioinformatics and three machine learning algorithms, four SA deposition-related potential biomarkers, namely ACLY, FASN, ME1, and ARVCF were selected. FASN was evaluated as the most valuable biomarker for the SA mechanism. The 18 down- and 34 up-regulated DEGs in the IMF group were identified, and ACTA2 and HMGCL were screened as the IMF deposition-related candidate core genes, especially the ACTA2 may play the critical role in IMF deposition regulation. Moreover, based on the constructed ceRNA network, we postulated that the role of predicted ceRNA interaction network of XIST, NEAT1/miR-15a-5p, miR-16-5p, miR-424-5p, miR-497-5p/FASN were vital in the SA metabolism, XIST, NEAT1/miR-27a/b-3p, 181a/c-5p/ACTA2 might contribute to the regulation to IMF metabolism, which all gave suggestions in molecular mechanism for regulation of fat deposition. These findings may facilitate advancements in porcine quality at the genetic and molecular levels and assist with human obesity-associated diseases.

Heavy Pigs Reared for Italian Dry-Cured Products: Does Immunocastration Influence the Fatty Acid Profile of Loins and Backfat?

The Italian pig sector requires heavy pigs (raised for at least nine months and slaughtered at >160 kg). In order to avoid boar taint and lower the impact on welfare, immunocastration provides an alternative to surgical castration. This study investigated the effects of immunocastration compared to surgical castration on the chemical composition and fatty acid profile of loins (longissimus dorsi muscle) and adipose tissue in Italian heavy pigs raised for dry-cured ham. Twenty-four male pigs were subjected to surgical castration (n = 12) or immunocastration (n = 12). Carcass parameters were monitored at slaughter, and samples of longissimus dorsi muscle and subcutaneous fat were analysed. This study showed no significant differences in carcass characteristics and proximate composition of fresh meat. However, variations were observed in the fatty acid profiles of meat and adipose tissue between groups. Notably, saturated fatty acids, particularly stearic acid (18:0), were higher in the intramuscular fat (IMF) of the immunocastrated pigs compared to the surgically castrated pigs. Conversely, monounsaturated fatty acids, predominantly oleic acid (18:1n-9), were higher in the IMF from the surgically castrated pigs compared to the immunocastrated pigs. While immunocastration may offer benefits in terms of animal growth and carcass composition, it could lead to unfavourable lipid changes in fresh loin meat for Italian heavy pigs.

Heterogeneity of Intramuscular, Intermuscular, and Subcutaneous Fat in Laiwu Pigs: Insights from Targeted Lipidomics and Transcriptomics

In the livestock industry, an excessive accumulation of subcutaneous fat diminishes the proportion of lean meat, while elevated intramuscular fat (IMF) content is associated with enhanced meat quality. However, the heterogeneity of various fat depots in pigs remains incompletely understood. Comprehensive tissue section, lipidomic, and transcriptomic analyses indicated that the maturity of IMF was significantly less than that of both intermuscular and subcutaneous fats. We identified 467 lipids across 29 lipid classes in total, revealing that IMF exhibits unique lipid composition and transcriptional profiles. More importantly, several lipids, including GalCer, S1P, CL, AcCa, PC-O, PE-O, and sulfatide, are highly enriched in intramuscular fat and may play pivotal roles in neuromodulation, mitochondrial function, lipogenesis, and membrane signaling. In conclusion, we unveiled unique lipid composition and molecular regulatory pathways of porcine IMF, offering new insights for the synergistic breeding that aims at optimizing pig backfat thickness and IMF content.

Characterization and Function Analysis of miRNA Editing during Fat Deposition in Chinese Indigenous Ningxiang Pigs.

This study aimed to identify active miRNA editing sites during adipose development in Ningxiang pigs and analyze their characteristics and functions. Based on small RNA-seq data from the subcutaneous adipose tissues of Ningxiang pigs at four stages-30 days (piglet), 90 days (nursery), 150 days (early fattening), and 210 days (late fattening)-we constructed a developmental map of miRNA editing in the adipose tissues of Ningxiang pigs. A total of 505 miRNA editing sites were identified using the revised pipeline, with C-to-U editing types being the most prevalent, followed by U-to-C, A-to-G, and G-to-U. Importantly, these four types of miRNA editing exhibited base preferences. The number of editing sites showed obvious differences among age groups, with the highest occurrence of miRNA editing events observed at 90 days of age and the lowest at 150 days of age. A total of nine miRNA editing sites were identified in the miRNA seed region, with significant differences in editing levels (p < 0.05) located in ssc-miR-23a, ssc-miR-27a, ssc-miR-30b-5p, ssc-miR-15a, ssc-miR-497, ssc-miR-15b, and ssc-miR-425-5p, respectively. Target gene prediction and KEGG enrichment analyses indicated that the editing of miR-497 might potentially regulate fat deposition by inhibiting adipose synthesis via influencing target binding. These results provide new insights into the regulatory mechanism of pig fat deposition.

Investigation of the cyclic separation of dioxins from municipal solid waste incineration fly ash by using fat

It is necessary to detoxify municipal solid waste incineration fly ash (MSWIFA) to facilitate resource utilization. The current research focused on the treatment of heavy metals in MSWIFA which is relatively well-developed, while dioxins (PCDD/Fs) need to be treated with more referable programs. Based on the excellent lipophilicities of dioxins, readily available, nontoxic, harmless, and easily treatable animal fats have been used to separate the dioxins from MSWIFA samples, thereby reducing the toxic equivalence of the MSWIFA. The experimental results indicated that animal fats significantly reduced the toxic equivalence of untreated, water-washed, and acid-washed MSWIFA samples, with reductions in the dioxin toxicity equivalence of up to 70%. Furthermore, in studies of heavy metal leaching, water washing followed by pig fat (FP) separation was identified as the optimal approach for the separation of dioxins from MSWIFA. Under the optimal conditions, the toxicity due to dioxins was reduced by over 70% after separation from MSWIFA with recycled animal fats. The environmental and economic benefits of this treatment option were analyzed on this basis.

Dietary iron or inulin supplementation alters iron status, growth performance, intramuscular fat and meat quality in finisher pigs

Forty LW × L pigs (20 boars and 20 gilts) (51.1 ± 0.41 kg) were allocated to a 2 × 2 × 2 factorial design with the respective factors being supplemental organic iron (Fe, 0 and 500 mg/kg), inulin (In, 0 and 50 g/kg) and sex (boars and gilts). After 5 weeks the animals were transported to an abattoir before slaughter and collection of samples. Serum iron was increased by supplemental Fe (28.4 v. 30.9 μmol/L, P = 0.05), although there was an interaction (P = 0.03) such that pigs fed diets with In had lower serum Fe concentrations than those without In (26.8 v. 32.3 μmol/L). Boars had lower (P < 0.01) haemoglobin (116 vs 125), haematocrit (36.7 v. 39.7%) and erythrocyte (6.6 v. 7.1 × 106/mL) concentrations than gilts. Dietary In increased liveweight gain (795 v. 869 g/d, P < 0.02) and carcass weight (62.9 v. 65.2 kg, P < 0.02). Dietary Fe or In supplementation did not improve muscle Longissimus thoracis et lumborum (LTL) total Fe concentration (P > 0.05). Muscle non-heme Fe concentration was higher in Fe-supplemented pigs (P < 0.04) and gilts (P < 0.05) than their counterparts. Muscle heme Fe concentration was greater (3.04 vs 2.51, P < 0.05) in boars than in gilts. The LTL marbling score was greater (P < 0.01) for In-supplemented pigs, and the response was more notable when Fe and In were fed together. These data show that dietary supplementation of Fe increased serum Fe and muscle non-heme Fe concentrations. Supplementation of In at 5% in the diet of finisher pigs improved liveweight gain and the marbling score of pork.

Retroviral Insertion Polymorphism (RIP) of Porcine Endogenous Retroviruses (PERVs) in Pig Genomes.

Endogenous retroviruses (ERVs) are one of the superfamilies of long terminal repeat retrotransposons (LTRs) in mice and humans. Approximately 8% of the pig genome is composed of sequences derived from LTRs. While the majority of ERVs in pigs have decayed, a small number of full-length copies can still mobilize within the genome. This study investigated the unexplored retroviral insertion polymorphisms (RIPs) generated by the mobilization of full-length ERVs (Fl-ERVs), and evaluated their impact on phenotypic variation to gain insights into the biological role of Fl-ERVs in pigs. Overall, 39 RIPs (insertions or deletions relative to the pig reference genome) generated by Fl-ERVs were predicted by comparative genomic analysis, and 18 of them were confirmed by PCR detection. Four RIP sites (D5, D14, D15, and D18) were further evaluated by population analysis, and all of them displayed polymorphisms in multiple breeds. The RIP site of ERV-D14, which is a Fl-ERV inserted in the STAB2-like gene, was further confirmed by sequencing. Population analysis of the polymorphic site of ERV-D14 reveals that it presents moderate polymorphism information in the Large White pig breed, and the association analysis reveals that the RIP of ERV-D14 is associated with age variations at 30 kg body weight (p < 0.05) and 100 kg body weight (p < 0.01) in the population of Large White pigs (N = 480). Furthermore, the ERV-D14 RIP is associated with changes in the expression of the target gene STAB2-like in the liver, backfat, and leaf fat in Sushan pigs. These data suggest that some Fl-ERVs are still mobilizing in the pig's genome, and contribute to genomic and phenotypic variations.