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Optimizing fat deposition is crucial for improving chicken production and meat quality. This study investigated the interactive roles of host genetics and gut microbiome in regulating abdominal fat deposition in selectively bred broiler chicken lines. We compared the gut microbiome composition and host whole-genome profiles between fat-line and lean-line broiler chickens that had been selectively bred for divergent abdominal fat levels over 15 generations. Despite identical dietary and environmental conditions, the two chicken lines exhibited significant differences in their gut microbiota. Lean-line broiler chickens exhibited an increased abundance of intestinal Lactobacillus and a decreased presence of potentially pathogenic species, such as Campylobacter coli, Corynebacterium casei, and Enterococcus faecalis. These microbial alterations were accompanied by shifts in the functional metagenome, with enrichment in pathways involved in energy metabolism and nutrient utilization in the lean-line chickens. Notably, the selective breeding process also led to genomic variations in the lean broilers, with single nucleotide polymorphisms predominantly observed in genes related to energy and lipid metabolism. Our findings suggest that the host–microbiome interactions play a key role in the divergent abdominal fat deposition phenotypes observed in these selectively bred chicken lines. The co-evolution of the gut microbiome and host genetics highlights the importance of considering both factors to optimize poultry production efficiency and meat quality. This study offers new insights into the intricate gut–genome interactions in chicken fat metabolism, paving the way for more effective breeding and microbiome-based strategies to manage adiposity in poultry.

The fat deposition of different adipose tissues is widely recognized as correlated, with distinct effects on meat quality traits and reproductive performance in poultry. In this study, we utilized lipidomics and transcriptomics analyses to investigate the heterogeneity and regulators of intramuscular fat (IMF), abdominal fat (AF), and subcutaneous fat (SF) in geese. Lipidomic profiling revealed 165, 129, and 77 differential lipid molecules (DLMs) between AF vs. IMF, SF vs. IMF, and SF vs. AF, respectively, with 47 common DLMs identified between AF vs. IMF and SF vs. IMF. Transcriptomic analysis identified 3369, 5758, and 131 differentially expressed genes (DEGs) between AF vs. IMF, SF vs. IMF, and SF vs. AF, respectively, with 2510 common DEGs identified between AF vs. IMF and SF vs. IMF. The KEGG results indicate that DLMs were predominantly enriched in glycerophospholipid and glycerolipid metabolism pathways, while DEGs were primarily enriched in metabolic pathways. Pearson correlation analysis identified FABP4, LPL, PLCB1, DSE, and PDE5A as potential factors influencing fat deposition. This study elucidates the heterogeneity and regulatory factors of different adipose tissues in geese, offering new insights for targeted improvements in goose meat quality and production efficiency.

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.

Excessive lipid deposition in layer chickens due to inappropriate feeding adversely affects egg production; however, nutritional manipulation methods to deal with this issue are still limited. β-hydroxy-β-methylbutyrate (HMB), a metabolite of L-leucine, was recently reported as a lipid-lowering nutrient in mice and pigs, although its role in layers had not been investigated. Here, we employed high-fat and high-cholesterol diet (HFHCD)−challenged growing layers as an obese model to explore HMB function in the regulation of lipid metabolism and the potential mechanisms involved. We found that dietary supplementation with (0.05% or 0.10%) HMB significantly reduced HFHCD−induced bodyweight growth in layers, mainly due to reduction in abdominal fat deposition. Mechanistically, HMB supplementation enhanced hepatic bile acid synthesis from cholesterol through elevating expression of Cyp7a1, a gene coding a key enzyme in bile acid synthesis. Furthermore, 16S rRNA gene sequencing revealed that HMB supplementation remodeled the diversity and composition of the layers’ cecal microbiota, and the abundance of Bacteroidetes at the phylum level were especially affected. Correlation analysis further indicated a strong negative association between Bacteroidetes abundance and lipid metabolism−related parameters. Taken together, these data suggest that dietary HMB supplementation could improve abdominal fat deposition in layers, probably through modulating hepatic bile acid synthesis and gut microbiota function.

Fat deposition is an important factor affecting meat quality and feed conversion efficiency in meat ducks. This study aims to identify key circRNAs and genes affecting abdominal fat deposition. The correlations between abdominal fat and other growth performances were analyzed in 304 F2 generation of Cherry Valley duck Runzhou Crested White ducks, and an RNA-seq analysis of abdominal fat tissues from ducks with high and low rates of abdominal fat was performed. Growth performance results showed that Abdominal fat ratio and Intramuscular fat were significantly higher in the high rates of abdominal fat (HF)group than in the low rates of abdominal fat (LF) group for ducks. RNA-seq analysis of abdominal fat tissue unveiled 85 upregulated and 72 downregulated circRNAs among the differentially expressed ones. Notably, 74 circRNAs displayed more than four-fold differential expression, constituting 47.13% of the differentially expressed genes. Functional enrichment analysis of the differentially expressed circRNA source and target genes indicated that 17 circRNAs might partake in regulating duck abdominal fat production by influencing pathways like PPAR signaling, lipid droplets, and triglyceride metabolism. Lastly, multiple circRNA-microRNA-messenger RNA interaction networks were constructed. The results of this study establish the groundwork for understanding the molecular mechanisms that regulate abdominal fat deposition in ducks, offering a theoretical reference for the selective breeding of high-quality meat-producing ducks.

It has been shown that tail fat content varies significantly among sheep breeds and plays a significant role in meat quality. Recently, significant efforts have been made to understand the physiological, biochemical, and genomic regulation of fat deposition in sheep tails in order to unravel the mechanisms underlying energy storage and adipose tissue lipid metabolism. RNA-seq has enabled us to provide a high-resolution snapshot of differential gene expression between fat- and thin-tailed sheep breeds. Therefore, three RNA-seq datasets were meta-analyzed for the current work to elucidate the transcriptome profile differences between them. Specifically, we identified hub genes, performed gene ontology (GO) analysis, carried out enrichment analyses of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and validated hub genes using machine learning algorithms. This approach revealed a total of 136 meta-genes, 39 of which were not significant in any of the individual studies, indicating the higher statistical power of the meta-analysis. Furthermore, the results derived from the use of machine learning revealed POSTN, K35, SETD4, USP29, ANKRD37, RTN2, PRG4, and LRRC4C as substantial genes that were assigned a higher weight (0.7) than other meta-genes. Among the decision tree models, the Random Forest ones surpassed the others in adipose tissue predictive power fat deposition in fat- and thin-tailed breeds (accuracy > 0.85%). In this regard, combining meta-analyses and machine learning approaches allowed for the identification of three important genes (POSTN, K35, SETD4) related to lipid metabolism, and our findings could help animal breeding strategies optimize fat-tailed breeds’ tail sizes.

Sugar-induced metabolic imbalances are a major health problem since an excessive consumption of saccharides has been linked to greater obesity rates at a global level. Sucrose, a disaccharide composed of 50% glucose and 50% fructose, is commonly used in the food industry and found in a range of fast, restaurant, and processed foods. Herein, we investigated the effects of a TRPC4/TRPC5 blocker, ML204, in the metabolic imbalances triggered by early exposure to sucrose-enriched diet in mice. TRPC4 and TRPC5 belong to the family of non-selective Ca+2 channels known as transient receptor potential channels. High-sucrose (HS)-fed animals with hyperglycaemia and dyslipidaemia, were accompanied by increased body mass index. mesenteric adipose tissue accumulation with larger diameter cells and hepatic steatosis in comparison to those fed normal diet. HS mice also exhibited enhanced adipose, liver, and pancreas TNFα and VEGF levels. ML204 exacerbated hyperglycaemia, dyslipidaemia, fat tissue deposition, hepatic steatosis, and adipose tissue and liver TNFα in HS-fed mice. Normal mice treated with the blocker had greater hepatic steatosis and adipose tissue cell numbers/diameter than those receiving vehicle, but showed no significant changes in tissue inflammation, glucose, and lipid levels. The results indicate that TRPC4/TRPC5 protect against the metabolic imbalances caused by HS ingestion.

It is well known that N6-methyladenosine (m6A) is the most abundant modification in linear RNA molecules, but many circRNA molecules have now been found to have a wide range of m6A modification sites as well. However, there are few relevant studies and information on the expression profile and functional regulatory properties of m6A-modified circRNAs (m6A-circRNAs) in longissimus dorsi. In this study, a total of 12 putative m6A-circRNAs were identified and characterized in the longissimus dorsi of Queshan Black and Large White pigs—8 of them were significantly more expressed in the longissimus dorsi of Queshan Black than in Large White pigs, while the other 4 were the opposite. These 12 putative m6A-circRNAs were also found to act as miRNA sponge molecules to regulate fat deposition by constructing the ceRNA regulatory network. Enrichment analysis also revealed that the 12 m6A-circRNAs parent genes and their adsorbed miRNA target genes were widely involved in fat deposition and cell proliferation and differentiation-related pathways, such as the HIF-1 signaling pathway, the pentose phosphate pathway, the MAPK signaling pathway, the glycosphingolipid biosynthesis-lacto and neolacto series, and the TNF signaling pathway, suggesting that the analyzed m6A-circRNAs may be largely involved in the formation of pork quality. These results provide new information to study the regulatory properties of m6A-circRNAs in the formation of pork quality.

Licha black (LI) pig has the specific characteristics of larger body length and appropriate fat deposition among Chinese indigenous pigs. Body length is one of the external traits that affect production performance, and fat deposition influences meat quality. However, the genetic characteristics of LI pigs have not yet been systematically uncovered. Here, the genomic information from 891 individuals of LI pigs, commercial pigs, and other Chinese indigenous pigs was used to analyze the breed characteristics of the LI pig with runs of homozygosity, haplotype, and FST selection signatures. The results showed the growth traits-related genes (i.e., NR6A1 and PAPPA2) and the fatness traits-related gene (i.e., PIK3C2B) were the promising candidate genes that closely related to the characteristics of LI pigs. In addition, the protein–protein interaction network revealed the potential interactions between the promising candidate genes and the FASN gene. The RNA expression data from FarmGTEx indicated that the RNA expression levels of NR6A1, PAPPA2, PIK3C2B, and FASN were highly correlated in the ileum. This study provides valuable molecular insights into the mechanisms that affect pig body length and fat deposition, which can be used in the further breeding process to improve meat quality and commercial profitability.

BSCL2 encodes seipin, a transmembrane endoplasmic reticulum protein associated with lipodystrophy and severe metabolic complications, including diabetes and hepatic steatosis. In pigs, BSCL2 expression increases during adipocyte differentiation. In the present study, we identified significant gene variants associated with fat deposition (FD)-related processes based on subcutaneous fat tissue RNA-seq data. In the association study, to prove our hypothesis, three Polish pig breeds were included: Złotnicka White (ZW, n = 72), Polish Landrace (PL, n = 201), and Polish Large White (PLW, n = 169). Based on variant calling analysis and χ2 tests, BSCL2 mutations showing significantly different genotype/allele distribution between high- and low-fat pigs were selected for a comprehensive association study. Four interesting BSCL2 variants (rs346079334, rs341493267, rs330154033, and rs81333153) belonging to downstream and missense mutations were investigated. Our study showed a significant decrease in minor allele frequency for two BSCL2 variants (rs346079334 and rs341493267) in PL pigs in 2020–2021. In ZW, BSCL2 mutations significantly affected loin and ham fats, meat redness, and growth performance traits, such as feed conversion and daily feed intake. Similar observations were noted for PLW and PL, where BSCL2 mutations influenced fat depositions and meat traits, such as loin eye area, loin mass and fat, carcass yield, and growth performance traits. Based on the observation in pigs, our study supports the theory that BSCL2 expressed in subcutaneous fat is involved in the FD process.

Lactobacillus spp., as probiotics, have shown efficacy in alleviating nonalcoholic fatty liver disease (NAFLD). Here, we screened a new probiotic strain, Lactobacillus salivarius SNK-6 (L. salivarius SNK-6), which was isolated from the ileum of healthy Xinyang black-feather laying hens in China. We investigated the beneficial activity of L. salivarius SNK-6 in a NAFLD model in laying hens and found that L. salivarius SNK-6 inhibited liver fat deposition and decreased serum triglyceride levels and activity of aspartate transaminase and alanine transaminase. MBOAT2 (membrane-bound O-acyltransferase domain containing 2) was directly targeted by miR-130a-5p, which was downregulated in the liver of NAFLD laying hens but reversed after L. salivarius SNK-6 treatment. Downregulation of MBOAT2, L. salivarius SNK-6 supplementation in vivo, and L. salivarius SNK-6 cell culture treatment in vitro suppressed the mRNA expression of genes involved in the PPAR/SREBP pathway. In addition, 250 metabolites were identified in the supernatants of L. salivarius SNK-6 culture media, and most of them participated in metabolic pathways, including amino acid, carbohydrate, and lipid metabolism. Targeted metabolomic analysis revealed that acetate, butyrate, and propionate were the most abundant short-chain fatty acids, while cholic acid, ursodeoxycholic acid, chenodeoxycholic acid, and tauroursodeoxycholic acid were the four most-enriched bile acids among L. salivarius SNK-6 metabolites. This may have contributed to the reparative effect of L. salivarius SNK-6 in the NAFLD chicken model. Our study suggested that L. salivarius SNK-6 alleviated liver damage partly via the miR-130a-5p/MBOAT2 signaling pathway.

Excessive fat accumulation is a common phenomenon in cultured fish, which can cause metabolic disease such as fatty liver. However, the relative regulatory approach remains to be explored. Based on this, two feeding trials were conducted. Firstly, fish were fed either a normal-fat diet (NFD) or a high-fat diet (HFD) for eight weeks and sampled at the 2nd, 4th, 6th, and 8th week after feeding (Experiment I). In the first four weeks, fish fed an HFD grew faster than those fed an NFD. Conversely, the body weight and weight gain were higher in the NFD group at the 6th and 8th weeks. Under light and transmission electron microscopes, fat accumulation of the liver was accompanied by an obvious endoplasmic reticulum (ER) swell. Accordingly, the expressions of atf-6, ire-1, perk, eif-2α, atf-4, grp78, and chop showed that ER stress was activated at the 6th and 8th weeks. In Experiment II, 50 mg/kg 4-PBA (an ERs inhibitor) was supplemented to an HFD; this was named the 4-PBA group. Then, fish was fed with an NFD, an HFD, and a 4-PBA diet for eight weeks. As the result, the excessive fat deposition caused by an HFD was reversed by 4-PBA. The expression of ER stress-related proteins CHOP and GRP78 was down-regulated by 4-PBA, and the transmission electron microscope images also showed that 4-PBA alleviated ER stress induced by the feeding of an HFD. Furthermore, 4-PBA administration down-regulated SREBP-1C/ACC/FAS, the critical pathways of fat synthesis. In conclusion, the results confirmed that ER stress plays a contributor role in the fat deposition by activating the SREBP-1C/ACC/FAS pathway. 4-PBA as an ER stress inhibitor could reduce fat deposition caused by an HFD via regulating ER stress.

Fat deposition is a crucial element in pig production that affects production efficiency, quality and consumer choices. In this study, Duroc pigs, a Western, famous lean pig breed, and Luchuan pigs, a Chinese, native obese pig breed, were used as animal materials. Transcriptome sequencing was used to compare the back adipose tissue of Duroc and Luchuan pigs, to explore the key genes regulating fat deposition. The results showed that 418 genes were highly expressed in the Duroc pig, and 441 genes were highly expressed in the Luchuan pig. In addition, the function enrichment analysis disclosed that the DEGs had been primarily enriched in lipid metabolism, storage and transport pathways. Furthermore, significant differences in the metabolic pathways of alpha-linolenic acid, linoleic acid and arachidonic acid explained the differences in the flavor of the two kinds of pork. Finally, the gene set enrichment analysis (GSEA) exposed that the difference in fat deposition between Duroc and Luchuan pigs may be due to the differential regulation of the metabolism pathway of fatty acid. Therefore, this study described the differential expression transcriptional map of adipose tissue of Duroc pig and Luchuan pig, identified the functional genes regulating pig fat deposition, and provided new hypotheses and references for further study of fat development.

Growth is frequently described as weight gain over time. Researchers have used this information in equations to predict carcass composition and estimate fat deposition. Diet, species, breed, and gender all influence fat deposition. Alterations in diets result in changes in fat deposition as well as the fatty acid profile of meat. Additionally, the amount and composition of the fat can affect lipid stability and flavor development upon cooking. Fat functions not only as a storage of energy and contributor of flavor compounds, but also participates in signaling that affects many aspects of the physiological functions of the animal. Transcription factors that are upregulated in response to excess energy to be stored are an important avenue of research to improve the understanding of fat deposition and thus, the efficiency of production. Additionally, further study of the inflammation associated with increased fat depots may lead to a better understanding of finishing animals, production efficiency, and overall health.

Pork quality is a factor increasingly considered in consumer preferences for pork. The formation mechanisms determining meat quality are complicated, including endogenous and exogenous factors. Despite a lot of research on meat quality, unexpected variation in meat quality is still a major problem in the meat industry. Currently, gut microbiota and their metabolites have attracted increased attention in the animal breeding industry, and recent research demonstrated their significance in muscle fiber development and fat deposition. The purpose of this paper is to summarize the research on the effects of gut microbiota on pig muscle and fat deposition. The factors affecting gut microbiota composition will also be discussed, including host genetics, dietary composition, antibiotics, prebiotics, and probiotics. We provide an overall understanding of the relationship between gut microbiota and meat quality in pigs, and how manipulation of gut microbiota may contribute to increasing pork quality for human consumption.

N6-methyladenosine (m6A) is the most prevalent internal form of modification in messenger RNA in higher eukaryotes and plays an important role in cancer, immunity, reproduction, development, and fat deposition. Intramuscular fat is the main factor used to measure the meat quality of an animal. The deposition of intramuscular fat and perirenal fat increases with age. However, there is no data on m6A modification of Rex rabbits and its potential biological roles in adipose deposition and muscle growth. Here, we performed two high-throughput sequencing methods, m6A-modified RNA immunoprecipitation sequence (MeRIP-seq) and RNA sequence (RNA-seq), to identify key genes with m6A modification on fat deposition in the muscle and adipose tissues of Rex rabbits. Then, qRT-PCR was used to identify the differently methylated genes related to fat deposition. Our findings showed that there were 12,876 and 10,973 m6A peaks in the rabbit muscle and adipose tissue transcriptomes, respectively. Stop codons, 3′-untranslated regions, and coding regions were found to be mainly enriched for m6A peaks. In addition, we found 5 differential methylases and 12 key genes of methylation modification related to fat deposition between muscle and adipose tissues samples. The expression levels of six random key genes were significantly higher in the fat than that in the muscle of Rex rabbits at different stages (p < 0.01). Finally, five differential methylases were found to regulate adipogenesis by affecting the expression of screened genes in different ways. These findings provided a theoretical basis for our future research on the function of m6A modification during the growth of fat deposits.

CircRNAs play an important role in fat deposition, and testosterone-deficient boars exhibit significantly increased fat deposition; however, the mechanism by which testosterone regulates fat deposition through circRNAs remains unclear. In this study, circRNA-seq of backfat and abdominal fat from castrated and intact full-sib Yorkshire pigs was performed. The GO and KEGG enrichment analyses revealed that the host genes of the dorsal DE circRNAs were mainly involved in fatty acid transport, while in abdominal tissues, these genes were mainly involved in adipogenesis and inflammation. The interaction among sus_circPAPPA2, ssc-miR-2366 and GK was verified by dual fluorescence experiments and in porcine preadipocytes. The overexpression of sus_circPAPPA2 significantly inhibited the differentiation of preadipocytes. The expression of sus_circPAPPA2 was increased after adding 100 nM of testosterone, and preadipocyte differentiation was significantly inhibited. Testosterone can affect preadipocyte differentiation by upregulating the expression of sus_circPAPPA2, sponging miR-2366 and regulating the expression of genes, such as GK. These results indicate that testosterone can regulate the expression of adipocyte differentiation- and lipid metabolism-related genes by regulating the expression of circRNA, and ceRNA networks are different in the testosterone regulation of adipose deposition in different parts. This study provides basic data enhancing the understanding of the interaction between the hormone environment and mir-2366/GK to regulate trait performance in pigs.

Emerging evidence suggests that mitochondrial dysfunction mediates the pathogenesis for non-alcoholic fatty liver disease (NAFLD). Hydroxytyrosol (HT) is a key component of extra virgin olive oil which can exert beneficial effects on NAFLD through modulating mitochondria. However, the mechanism of the impacts of HT still remains elusive. Thus, an in vivo and a series of in vitro experiments were carried out to examine the impacts of hydroxytyrosol (HT) on lipid metabolism and mitochondrial function in fish. For the in vivo experiment, two diets were produced to contain 10% and 16% fat as normal-fat and high-fat diets (NFD and HFD) and two additional diets were prepared by supplementing 200 mg/kg of HT to the NFD and HFD. The test diets were fed to triplicate groups of spotted seabass (Lateolabrax maculatus) juveniles for 8 weeks. The results showed that feeding HFD leads to increased fat deposition in the liver and induces oxidative stress, both of which were ameliorated by HT application. Furthermore, transmission electron microscopy revealed that HFD destroyed mitochondrial cristae and matrix and induced severe hydropic phenotype, while HT administration relieved these alterations. The results of in vitro studies using zebrafish liver cell line (ZFL) showed that HT promotes mitochondrial function and activates PINK1-mediated mitophagy. These beneficial effects of HT disappeared when the cells were treated with cyclosporin A (Csa) as a mitophagy inhibitor. Moreover, the PINK1-mediated mitophagy activation by HT was blocked when compound C (CC) was used as an AMPK inhibitor. In conclusion, our findings demonstrated that HT alleviates fat accumulation, oxidative stress and mitochondrial dysfunction, and its effects are deemed to be mediated via activating mitophagy through the AMPK/PINK1 pathway.

Castration is usually used to remove boar taint in commercial pork production, but the adipose accumulation was increased excessively, which affected the meat quality of pigs. Based on our previous study, secreted phosphoprotein 1 (SPP1) was significantly differentially expressed between castrated and intact male pigs. However, the role of SPP1 in regulating adipose growth and fat storage caused by castration is unknown. In this study, SPP1 was identified to inhibit adipogenesis by the expression of adipogenic markers PPARγ and FABP4 as well as Oil red staining assay during differentiation of porcine bone marrow mesenchymal stem cells (pBMSCs). Subsequently, testosterone was used to treat pBMSCs to simulate the androgen status of intact pigs. Compared with the control groups without testosterone, the SPP1 expression in the testosterone group was markedly increased in the late stage of pBMSCs differentiation. Furthermore, novel-miR-659 was predicted by TargetScan and miRDB to target SPP1 and verified through a dual-luciferase reporter assay. Oil Red O staining assay indicated that novel-miR-659 overexpression significantly promoted adipogenesis, whereas novel-miR-659 inhibition suppressed adipogenesis. The expressions of adipogenic markers PPARγ and FABP4 showed the same tendency. Taken together, our study found that the targeted interaction between novel-miR-659 and SPP1 is involved in regulation of fat deposition in castrated male pigs.

Fat deposition is the key factor affecting the efficiency of animal husbandry production. There are many factors affecting fat deposition, in which the gastrointestinal microbiota plays an important role. Therefore, the body mass index (BMI) was introduced into the evaluation of sheep fat deposition, and the different microbiota and functional pathways of the sheep gastrointestinal tract in different BMI groups were analyzed. We selected 5% of individuals with the highest and lowest BMI from a feed test population (357 in whole group). Microorganisms in 10 sites of the gastrointestinal tract in 36 individuals (18 in each group) were evaluated by 16S rRNA V3–V4 region sequencing. There were differences (p < 0.05) in fat deposition traits between different BMI groups. In the 10 parts of the gastrointestinal tract, the diversity and richness of cecal microflora in the high-BMI group were higher than those in low-BMI Hu sheep (p < 0.05). Principal coordinate analysis (PCoA) showed that there was separation of the cecum between groups, and there were differences in the cecal microbial community. Linear discriminant analysis effect size (LEfSe) showed that most biomarkers were in the cecum. On the basis of an indepth study of cecal microorganisms, 26 different bacterial genera were obtained (p < 0.05). Correlation analysis between them and the characteristics of fat deposition in sheep showed that Colidextribacter, Alloprevotella, and Succenivibrio were positively correlated with fat deposition, while Lachnospiraceae_ND3007_Group was negatively correlated (p < 0.05). The above results show that the cecum may be an important part leading to the difference of BMI in sheep, and its microorganisms may affect the level of fat deposition.

This study was conducted on two rabbit lines divergently selected for intramuscular fat (IMF) content in the Longissimus thoracis et lumborum (LTL) muscle. The aim was to estimate the direct response to selection for IMF after 10 generations, and the correlated responses in carcass quality traits, meat fatty acid content, liver fat and its fatty acid content, and in plasma metabolic markers related to liver metabolism. Selection for IMF content was successful, showing a direct response equivalent to 3.8 SD of the trait after 10 generations. The high-IMF line (H) showed a greater dissectible fat percentage than the low-IMF line (L), with a relevant difference (DH-L = 0.63%, Pr = 1). No difference was found in liver fat content (DH-L = −0.04, P0 = 0.62). The fatty acid content of both LTL muscle and liver was modified after selection. The LTL muscle had greater saturated (SFA; DH-L = 5.05, Pr = 1) and monounsaturated fatty acids (MUFA; DH-L = 5.04, Pr = 1) contents in the H line than in the L line. No relevant difference was found in polyunsaturated fatty acids content (PUFA; Pr = 0.05); however, greater amounts of C18:2n6 (DH-L = 3.03, Pr = 1) and C18:3n3 (DH-L = 0.56, Pr = 1) were found in the H than in the L line. The liver presented greater MUFA (DH-L = 1.46) and lower PUFA (DH-L = −1.46) contents in the H than in the L line, but the difference was only relevant for MUFA (Pr = 0.86). The odd-chain saturated fatty acids C15:0 and C17:0 were more abundant in the liver of the L line than in the liver of the H line (DH-L = −0.04, Pr = 0.98 for C15:0; DH-L = −0.09, Pr = 0.92 for C17:0). Greater concentrations of plasma triglycerides (DH-L = −34) and cholesterol (DH-L = −3.85) were found in the L than in the H line, together with greater plasma concentration of bile acids (DH-L = −2.13). Nonetheless, the difference was only relevant for triglycerides (Pr = 0.98).

The present study is aimed to explore the effects of different dietary beta-hydroxy-beta-methyl butyrate (HMB) levels (0, 0.05%, 0.10%, or 0.15%) on liver lipid metabolism on Wenshi broiler chickens. Results showed that HMB reduced the liver weight as well as liver concentrations of triacylglycerol (TG) and total cholesterol (TC) (quadratically, p < 0.05), and the lowest values were observed in the 0.10% HMB group. Meanwhile, HMB supplementation significantly altered the expression levels of key genes related to lipid metabolism in the liver of broiler chickens (p < 0.05). Furthermore, 16S rRNA gene sequencing revealed that HMB supplementation could greatly change the richness, diversity, and composition of the broiler gut microbiota, and the Bacteroidetes relative abundance at the phylum level and the Alistipes relative abundance at the genus level were affected (p < 0.05). Correlation analysis further suggested a strong association between Bacteroidetes relative abundance and lipid metabolism-related parameters (p < 0.05). Together, these data suggest that 0.10% HMB supplementation could inhibit hepatic fat deposition via regulating gut microbiota in broilers.

Microbial communities of the sheep rumen have been studied extensively; however, their involvement in the regulation of fat deposition is unknown. Herein, we aimed to identify the correlations among fat deposition-related phenotypes and the effect of microbiota on changes in body fat accumulation. The rumen microbiota of 141 lambs was profiled by 16S ribosomal RNA sequencing, and the volatile fatty acids’ (VFAs’) concentrations were quantified by gas chromatography. Subsequently, the animals were grouped according to body mass index (BMI) to compare the microbiota of the rumen among the sheep with different fat deposition levels. Results further revealed differences in terms of the species abundance, diversity, and microbial composition between sheep with different fat deposition levels. Linear discriminant analysis (LDA) Effect Size (LEfSe) analysis and Random Forest (RF) regression analysis identified changes in 29 ruminal bacteria, which may be the main driver for different fat deposition.

This study was designed to investigate the influence of pellet fibre level, milk replacer composition and age at weaning on growth and body composition of lambs reared artificially. Romney ram lambs were randomly allocated to one of three rearing treatments; HFP57: commercial milk replacer to 57 days of age, and high fibre concentrate pellets; HFP42: commercial milk replacer with early weaning at 42 days of age, and high fibre concentrate pellets; LFP42: high protein milk replacer from 2–16 days of age followed by commercial milk replacer with early weaning at 42 days of age, and low fibre concentrate pellets. Lambs were slaughtered at 57 days of age. Overall average daily liveweight gain of lambs did not differ (p > 0.05) between treatments. Dressing out percentage, carcass weight, empty small intestine and omental fat were higher (p < 0.05) in HFP57 than in both HFP42 and LFP42 lambs. HFP42 and LFP42 lambs had heavier (p < 0.05) empty rumen weights. Whole body protein content was higher (p < 0.05) in HFP42 lambs compared to both HFP57 and LFP42 lambs. Fat content and daily fat deposition were greater (p < 0.05) in HFP57 lambs than HFP42 and LFP42 lambs. Weaning lambs at 42 days of age with provision of either low or high fibre concentrate pellets, resulted in similar growth rates, reduced whole body fat deposition and was a more cost-effective rearing regimen.

The present study was conducted to investigate the effects of diet with betaine supplementation on the growth performance, carcass quality and fat deposition in finishing Ningxiang pigs. A total of 24 Ningxiang pigs (43.6 ± 5.34 kg of average body weight) was randomly divided into two groups, with 6 replicates per treatment and 2 pigs per replicate. The treatments included a control group (basal diet) and a test group (basal diet + 0.2% betaine). The whole trial lasted 81 days. At the end of the experiment, one pig (close to the average body weight of all experimental pigs) per replicate was slaughtered to determine the carcass traits, meat quality and the mRNA expression levels of genes relate to fat deposition (one pig per replicate was randomly selected and fasted for 12 h, n = 6). Results indicated that growth performance was not changed with betaine supplementation. However, dietary with betaine supplementation decreased back fat thickness and fat percentage, and increased the lean meat percentage as well (p < 0.05). In addition, diet with betaine supplementation reduced drip loss, water loss, cooking loss, shear force and b × 24 h value of meat (p < 0.05). There was no difference in total moisture, ether extract and crude protein of longissimus thoracis between the control and test group. Dietary with betaine supplementation decreased ether extract and total cholesterol (p < 0.05) in liver. Dietary with betaine supplementation upregulated the mRNA expression levels of adipose triglyceride lipase (ATGL) and sirtuin 1 (Sirt1), while downregulated the mRNA expression levels of fatty acid synthase (FAS) and acetyl CoA carboxylase (ACC) in subcutaneous fat of back (p < 0.05). Besides, dietary with betaine supplementation upregulated the fatty acid binding protein 4 (FABP4) mRNA expression of longissimus thoracis in finishing Ningxiang pigs (p < 0.05). These results showed that diet supplemented with betaine could improve the slaughtering performance and meat quality, and regulate the genes expression to affect the fat deposition in finishing Ningxiang pigs.

Liver is responsible for 90% of lipid synthesis in poultry; thus, it plays an important role in the growth of Muscovy ducks, which have a high fat deposition ability in a time-dependent manner. Therefore, male Muscovy ducks at 14, 28, 42, and 56 days were selected for body weight (BW), carcass weight (CW), subcutaneous fat thickness (SFT), abdominal fat weight (AFW), intramuscular fat content (IMF), and breast muscle fiber (BMF) diameter and density determination. Two-dimensional electrophoresis (2-DE) combining liquid chromatography linked to tandem mass spectrometry (LC-MS/MS) was used to analyze proteomic changes in liver at each stage. The BW, CW, AFW, SFT, and BMF diameter and density were significantly increased, while IMF content was significantly decreased at 28 to 42 days of age (p < 0.05). There were 57 differentially abundant protein (DEP) spots representing 40 proteins identified among the ages, in which 17, 41 and 4 spots were differentially abundant at 14 vs. 28, 28 vs. 42, and 42 vs. 56, respectively. Gene Ontology enrichment analysis found that DEPs were mostly enriched in the oxidation-reduction process, carboxylic acid metabolism, etc. Protein–protein interaction showed that catalase (CAT), triosephosphate isomerase (TPI), and protein disulfide-isomerase (PDI) were the key proteins responsible for the growth of Muscovy duck. In conclusion, 28 to 42 days of age is the crucial period for Muscovy ducks, and the ability of metabolism and antioxidants were significantly enhanced in liver.

This study was conducted to elucidate the interaction effects of temperature and dietary lipid levels (2 × 2 factorial experiment) on the growth performance, muscle, and liver composition in adult farmed European sea bass (Dicentrarchus labrax). Two groups of fish (190 g; 60 fish per group) were distributed in 12 tanks in triplicates and kept at two different temperature regimes; one starting at 23 °C and then changed to 17 °C for 61 days, and the other starting at 17 °C and then changed to 23 °C for 39 days. Two commercial diets containing both ~44% crude protein but incorporating different dietary lipid levels, 16.5% (D16) and 20.0% (D20) (dry matter (DM)), were fed to the fish to apparent satiation; the type of diet fed to each fish group remained constant throughout the experiment. Final body weight, weight gain, and specific growth rate were significantly higher for the fish group held at 23 °C compared to the fish group at 17 °C (before the temperature changes), while the dietary fat content did not have any profound effect in both groups. Furthermore, the different temperature regimes did not affect muscle or liver composition, but, on the contrary, dietary lipids affected hepatosomatic, perivisceral fat, and visceral indexes. Feed conversion ratio and specific growth rate were not affected by the dietary lipid level. An interaction of temperature and dietary lipid content was observed in daily feed consumption (DFC) and final body weight (FBW).

In this study, the effects of a nocturnal light pulse on body weight, organ mass, gonadal function, and plasma levels of metabolites were determined in male mule ducks. In total, 32 15-week-old mule ducks were randomly allocated to either Group C (control group) or L+ (lighting group). Group C was exposed to the natural photoperiod, whereas Group L+ was provided with a 1-h lighting over 20:00–21:00 every day, in addition to the natural photoperiod. At the end of the 42-day experiment, Group L+ had significantly lower relative weights (% of live weight) of the digestive tract and abdominal fat and higher relative weights of the breast meat and testes than Group C. Moreover, Group L+ had significantly higher plasma testosterone and lower plasma glucose levels. However, no between-group differences were observed in the triacylglycerol and uric acid levels. Histological examination demonstrated that the seminiferous tubule diameter was larger in Group L+ than in Group C. Moreover, the meiosis stage in spermatogenesis had begun in Group L+ but not in Group C. In conclusion, the supplemented 1-h lighting at 20:00 stimulated gonadal development and function and reduced fat deposition.

This study aimed to study the role of PPARs on fat deposition in native crossbred chicken. We studied the growth, abdominal, subcutaneous, and intramuscular fat, and mRNA expression of PPARA and PPARG in adipose and muscle tissues of four chicken breeds (CH breed (100% Thai native chicken), KM1 (50% CH background), KM2 (25% CH background), and broiler (BR)). The result shows that the BR chickens had higher abdominal fat than other breeds (p < 0.05) and the KM2 had an abdominal fat percentage higher than KM1 and CH respectively (p < 0.05). The intramuscular fat of BR was greater than KM1 and CH (p < 0.05). In adipose tissue, PPARA expression was different among the chicken breeds. However, there were breed differences in PPARG expression. Study of abdominal fat PPARG expression showed the BR breed, KM1, and KM2 breed significantly greater (p < 0.05) than CH. In 8 to 12 weeks of age, the PPARG expression of the CH breed is less than (p < 0.05) KM2. Crossbreeding improved the growth of the Thai native breed, there was also a corresponding increase in carcass fatness. However, there appears to be a relationship between PPARG expression and fat deposition traits. therefore, PPARG activity hypothesized to plays a key role in lipid accumulation by up-regulation.

Aflatoxin B1 (AFB1) leads to a major risk to poultry and its residues in meat products can also pose serious threat to human health. In this study, after feeding 165-day-old Roman laying hens for 35 days, the toxic effects of aflatoxin B1 at different concentrations were evaluated. The purpose of this study was to explore the mechanism of liver toxicosis responses to AFB1. We found that highly toxic group exposure resulted in liver fat deposition, increased interstitial space, and hepatocyte apoptosis in laying hens. Furthermore, a total of 164 differentially expressed lnRNAs and 186 differentially expressed genes were found to be highly correlated (Pearson Correlation Coefficient > 0.80, p-value < 0.05) by sequencing the transcriptome of control (CB) and highly toxic group (TB3) chickens. We also identify 29 differentially expressed genes and 19 miRNAs that have targeted regulatory relationships. Based on the liver cell apoptosis and fatty liver syndrome that this research focused on, we found that the highly toxic AFB1 led to dysregulation of the expression of PPARG and BCL6. They are cis-regulated by TU10057 and TU45776, respectively. PPARG was the target gene of gga-miR-301a-3p, gga-miR-301b-3p, and BCL6 was the target gene of gga-miR-190a-3p. In summary, highly toxic AFB1 affects the expression levels of protein-coding genes and miRNAs in the liver of Roman layer hens, as well as the expression level of long non-coding RNA in the liver, which upregulates the expression of PPARG and downregulates the expression of Bcl-6. Our study provides information on possible genetic regulatory networks in AFB1-induced hepatic fat deposition and hepatocyte apoptosis.

Pediatric obesity has a growing health and socio-economical impact due to cardiovascular and metabolic complications in adult life. Some recent studies suggest that live or heat-treated probiotics have beneficial effects in preventing fat deposition and obesity in preclinical and clinical sets. Here, we have explored the effects of heat-treated probiotic Bifidobacterium animalis subsp. lactis CECT 8145 (HT-BPL1), added as a supplement on an infant milk formula (HT-BPL1-IN), on Caenorhabditis elegans fat deposition and short-chain fatty acids (SCFAs) and lactate, using fermented baby fecal slurries. We have found that HT-BPL1-IN significantly reduced fat deposition in C. elegans, at the time it drastically augmented the generation of some SCFAs, particulary acetate and organic acid lactate. Data suggest that heat-treated BPL1 maintains its functional activities when added to an infant powder milk formula.

Fatty traits are very important in pig production. However, the role of microRNAs (miRNAs) in fat deposition is not clearly understood. In this study, we compared adipose miRNAs from three full-sibling pairs of female Landrace pigs, with high and low backfat thickness, to investigate the associated regulatory network. We obtained an average of 17.29 million raw reads from six libraries, 62.27% of which mapped to the pig reference genome. A total of 318 pig miRNAs were detected among the samples. Among them, 18 miRNAs were differentially expressed (p-value < 0.05, |log2fold change| ≥ 1) between the high and low backfat groups; 6 were up-regulated and 12 were down-regulated. Functional enrichment of the predicted target genes of the differentially expressed miRNAs, indicated that these miRNAs were involved mainly in lipid and carbohydrate metabolism, and glycan biosynthesis and metabolism. Comprehensive analysis of the mRNA and miRNA transcriptomes revealed possible regulatory relationships for fat deposition. Negatively correlated mRNA–miRNA pairs included miR-137–PPARGC1A, miR-141–FASN, and miR-122-5p–PKM, indicating these interactions may be key regulators of fat deposition. Our findings provide important insights into miRNA expression patterns in the backfat tissue of pig and new insights into the regulatory mechanisms of fat deposition in pig.

It is a unique feature that fat can be deposited in sheep tails and rumps. To elucidate the genetic mechanism underlying this trait, we collected 120 individuals from three Chinese indigenous sheep breeds with extreme tail types, namely large fat-tailed sheep (n = 40), Altay sheep (n = 40), and Tibetan sheep (n = 40), and genotyped them using the Ovine Infinium HD SNP BeadChip. Then genomic scan for selection signatures was performed using the hapFLK. In total, we identified 25 genomic regions exhibiting evidence of having been under selection. Bioinformatic analysis of the genomic regions showed that selection signatures related to multiple candidate genes had a demonstrated role in phenotypic variation. Nine genes have documented association with sheep tail types, including WDR92, TBX12, WARS2, BMP2, VEGFA, PDGFD, HOXA10, ALX4, and ETAA1. Moreover, a number of genes were of particular interest, including RXFP2 associated with the presence/absence and morphology of horns; MITF involved in coat color; LIN52 and SYNDIG1L related to the number of teats; MSRB3 gene associated with ear sizes; LTBP2 considered as a positional candidate genes for number of ribs; JAZF1 regulating lipid metabolism; PGRMC2, SPAG17, TSHR, GTF2A1, and LARP1B implicated with reproductive traits. Our findings provide insights into fat tail formation and a reference for carrying out molecular breeding and conservation in sheep.

This study aimed to investigate the changes of lipid-related gene and serum metabolites in broiler chickens fed with fermented cottonseed meal (FCSM) diet, through quantitative real-time PCR and metabolomics analysis. Totally, 180 1-day-old Cobb broilers were randomly assigned to two groups with six replicates of 15 birds in each. The two diets consisted of a control diet supplemented with 0% FCSM (CON group) and an experimental diet with 6% FCSM (fermented by Candida tropicalis) replacing the soybean meal (FCSM group). The results showed that both abdominal fat content and subcutaneous fat thickness significantly reduced (p < 0.05) in response to dietary FCSM supplementation at the age of 21 d. Serum concentrations of glucose, triglyceride, and low-density lipoprotein cholesterol decreased (p < 0.05) in FCSM fed broilers compared with CON fed broilers, while the levels of epinephrine and growth hormone in serum, liver and abdominal fat tissue were higher (p < 0.05) in FCSM than in CON fed broilers. The activity of hormone-sensitive esterase and lipoprotein lipase (LPL) in the liver and abdominal fat were higher (p < 0.05) in FCSM than CON group. Additionally, compared with the CON group (p < 0.05), the expression of peroxisome proliferator-activated receptor alpha and LPL genes were upregulated in the livers of FCSM group broilers. Gene expressions of hormone-sensitive lipase and LPL in the abdominal fat tissue were also upregulated (p < 0.05) with the broilers fed with FCSM diets. A total of 20 significantly different metabolites were obtained in the serum of different dietary FCSM supplemented fed broilers. The mainly altered pathways were clustered into organic acid metabolism, fatty acid metabolism, and amino acid metabolism. These results not only provide a better understanding of broilers’ lipid metabolism with FCSM but also can be helpful in further improvement of the broilers’ healthy production and utilization of FCSM.

Circular RNAs (circRNAs) have been identified as a novel type of regulators involved in multiple biological processes. However, circRNAs with a potential function in fat deposition in buffalo are poorly understood. In this study, six RNA libraries of adipose tissue were constructed for three young and three adult Chinese buffaloes with paired-ends RNA sequencing using the Illumina HiSeq 3000 platform. A total of 5141 circRNAs were computationally identified. Among them, 252 circRNAs were differentially expressed (DE) between the young and adult buffaloes. Of these, 54 were upregulated and 198 were downregulated in the adult group. Eight DE circRNAs were further identified by quantitative real-time-PCR (qRT-PCR) and Sanger sequencing. Co-expression analysis revealed that 34 circRNAs demonstrated a strong correlation with fat deposition-associated genes (|r| > 0.980). Among these, expressional correlation between two circRNAs (19:45387150|45389986 and 21:6969877|69753491) and PR/SET domain 16 was further verified using qRT-PCR, and a strong correlation was revealed (1 > |r| > 0.8). These results strongly suggest that circRNAs 19:45387150|45389986 and 21:6969877|69753491 are potential regulators of buffalo fat deposition. In summary, this study characterized the circRNA profiles of adipose tissues at different stages for the first time and revealed two circRNAs strongly correlated with fat deposition-associated genes, which provided new candidate regulators for fat deposition in buffalo.

In lean genotypes, protein restriction during growing increases intramuscular fat content without affecting the overall carcass fatness. The present study aims to assess the feasibility of applying this feeding management on an obese pig, the Cinta Senese, since obese genotypes are characterized by great lipogenic potential often leading to excessively high backfat deposits. Twenty pigs of average weight 38 kg, were divided in two groups, the first group was fed a protein restricted diet (9% of crude protein), while the second one a normal diet (13.5% of crude protein). During finishing, both groups were fed the same diet (10% of crude protein). Average daily gain, protein conversion index, backfat thickness, carcass weight, and prime cuts were determined. A loin sample joint was dissected in intermuscular fat, bone, subcutaneous fat, longissimus lumborum, and psoas major. On longissimus lumborum, physical and chemical analysis was carried out. The fatty acid profile of longissimus lumborum and loin subcutaneous fat were determined. Data were analyzed by analysis of variance. Protein conversion index resulted lower in the restricted group, while backfat was slightly greater. Meat quality traits were not affected by feeding management. Slightly modifications in subcutaneous outer layer fatty acids profile were observed. The protein restriction during growing did not seem a suitable mode of feeding management for Cinta Senese pigs.

Two hundred and ninety-four pigs were used to assess the effect of two ingredients (Lupinus albus (albus lupins) or a combination of calcium chloride and sodium tri-polyphosphate (mineral salts)) on growth performance, body composition and objective meat quality of pigs immunized against gonadotrophin releasing factor (immunocastrates) and entire male pigs in the late finishing phase. Pigs fed mineral salts ate less feed than those fed the control diet with no effect on growth rate (p > 0.05), backfat (p > 0.05) or fat deposition (p > 0.05). Pigs fed albus lupins had a reduced feed intake (p < 0.001 for all time periods), lower growth rate (p < 0.001 for all time periods), lower backfat (p < 0.005) and decreased fat deposition (p < 0.001 for all time periods) compared to those fed the control diet or mineral salts. From day (d) 0–28 pigs fed mineral salts had a better feed conversion ratio (p = 0.001) than those fed albus lupins who in turn had an improved feed conversion compared to the control diet. Immunocastrates had thicker backfat than entire males at the end of the experiment (p < 0.001), however, feeding albus lupins to immunocastrated males reduced backfat thickness to similar to entire males fed the control diet (p = 0.01). With the exception of the increased muscle pH at 45 minutes post-exsanguination in mineral salts and albus lupins compared with the control diet (p = 0.03) there was no effect of diet on objective pork quality. Pork from IC males had a higher ultimate pH (p < 0.001), was lighter (L*; p = 0.003), more yellow (p = 0.008) and had a higher drip loss (p < 0.001) compared to entire males. Albus lupins show potential in reducing the increase in feed intake and backfat associated with immunocastration. Mineral salts may be useful in situations where a reduction in feed intake and an improvement in feed conversion is desired and reducing fat deposition is not the objective.