Understanding the genetic basis and identifying quantitative trait loci (QTL) for age at first service (AFS) is essential for improving reproductive efficiency and reducing economic costs in heifers rearing. We conducted a genome-wide association study (GWAS) for AFS using the genomic estimated breeding values (GEBVs) of 3,686 Chinese Holstein heifers, genotyped with 7,964,217 single nucleotide polymorphisms (SNPs) after quality control. Significant SNPs and candidate genes were identified and investigated through colocalization analysis of GWAS, expression QTL (eQTL), and splicing QTL (sQTL), and expression analysis in blood RNA sequencing (RNA-seq). The heritability estimate for AFS was moderate at 0.276 ±0.025. Three QTL regions associated with AFS were identified: Region 1 on BTA6 (43688837-45007127 bp, 1.3 Mb with three 200kb windows), explaining 0.47% of genetic variance; Region 2 on BTA6 (62770788-62967316 bp) explaining 0.27% of the genetic variance; and Region 3 on BTA18 (6299721-6498934 bp) explaining 0.17% of the genetic variance. Combining GWAS and colocalization analysis, we identified ANAPC4, RBPJ, SEPSECS, SLC34A2, ZCCHC4 , CCDC149, GNPDA2, GUF1, DHX15, SOD3, GUF1 and GNPDA2 as candidate genes. These genes are enriched in signaling pathways such as progesterone-mediated oocyte maturation, parathyroid hormone synthesis, secretion and action, and selenocompound metabolism. ANAPC4, DHX15, GUF1, SEPSECS , and SOD3 were also differently expressed genes (DEGs) in blood RNA-seq. Integrating the GWAS, colocalization, differential expression analysis, and existing literature, ANAPC4 and rs136363104 were highlighted as the putative causal gene and variant for puberty, respectively. In conclusion, our study identified three candidate regions and 12 candidate genes, confirming ANAPC4 as a putative causal gene influencing AFS. This research enhances the understanding of the genetic basis of AFS in Chinese Holstein heifers. The identified key genomic regions, candidate genes, and variants have the potential to improve reproductive efficiency and reduce economic costs in heifer rearing. Interpretative summary The economic burden of heifer-raising and reproductive inefficiency in dairy cattle is evident. The most important strategy for optimizing heifer-raising is selecting heifers with earlier puberty (sexual maturity) to shorten age at first service (AFS). In this study, we have identified key genomic regions and candidate genes on AFS in Chinese Holstein heifers by genome-wide association study, and validated them by colocalization and RNA-seq analysis. The findings have the potential to enhance the understanding of the genetic basis of reproductive traits, leading to more targeted breeding strategies for improved reproductive efficiency. ### Competing Interest Statement The authors have declared no competing interest. * AFS : age at first service AFC : age at first calving QTL : quantitative trait loci eQTL : expression quantitative trait locus sQTL : splicing quantitative trait locus GWAS : genome-wide association study GEBV : genomic estimated breeding value AGEP : age at puberty RNA-seq : RNA sequencing LD : linkage disequilibrium GLM : general liner model CV : coefficient of variation IFLh : interval from first to last inseminations of heifers CRh : conception rate of heifers NS : number of repeated service GL : gestation length BiWh : birth weight of heifers National Key R&D Program of China, 2022YFF1001200

Serum/glucocorticoid-inducible kinase 1 (SGK1) gene encodes a serine/threonine protein kinase that plays an essential role in cellular stress response and regulation of multiple metabolic processes. However, its role in bovine adipogenesis remains unknown. In this study, we aimed to clarify the role of SGK1 in bovine lipid accumulation and improvement of meat quality. Preadipocytes were induced to differentiation to detect the temporal expression pattern of SGK1. Heart, liver, lung, spleen, kidney, muscle and fat tissues were collected to detect its tissue expression profile. Recombinant adenovirus and the lentivirus were packaged for overexpression and knockdown. Oil Red O staining, quantitative real-time PCR, Western blot analysis, Yeast two-hybrid assay, luciferase assay and RNA-seq were performed to study the regulatory mechanism of SGK1. SGK1 showed significantly higher expression in adipose and significantly induced expression in differentiated adipocytes. Furthermore, overexpression of SGK1 greatly promoted adipogenesis and inhibited proliferation, which could be shown by the remarkable increasement of lipid droplet, and the expression levels of adipogenic marker genes and cell cycle-related genes. Inversely, its knockdown inhibited adipogenesis and facilitated proliferation. Mechanistically, SGK1 regulates the phosphorylation and expression of two critical proteins of FoxO family, FOXO1/FOXO3. Importantly, SGK1 attenuates the transcriptional repression role of FOXO1 for PPARγ via phosphorylating the site S256, then promoting the bovine fat deposition. SGK1 is a required epigenetic regulatory factor for bovine preadipocyte proliferation and differentiation, which contributes to a better understanding of fat deposition and meat quality improvement in cattle.

Dorper sheep is popular among farming enterprises with strong adaptability, disease resistance, and roughage tolerance, and an unique characteristic of natural shedding of wool. In a large number of observations on experimental sheep farms, it was found that the wool of some sheep still had not shed after May, thus manual shearing was required. Therefore, understanding the molecular mechanisms of normal hair follicles (HFs) development is crucial to revealing the improvement of sheep wool-related traits and mammalian skin-related traits. In this study, transcriptome analysis was performed on skin tissues of adult Dorper ewes in the shedding (S) and non-shedding (N) groups in September 2019, January 2020, and March 2020, respectively. The results identified 3,278 differentially expressed transcripts (DETs) in the three comparison groups within the S group, 720 DETs in the three comparison groups within the N group, and 1,342 DETs in the three comparison groups between the S-vs-N groups. Time-series expression analysis revealed 2 unique expression patterns in HF development, namely, elevated expression in the anagen phase (A pattern) and the telogen phase (T pattern). DETs with stage-specific expression had a significant presence in processes related to the hair cycle and skin development, and several classic signaling pathways involved in sheep HF development, such as Rap1, estrogen, PI3K-Akt, and MAPK, were detected. Combined analysis of DETs, time-series expression data, and weighted gene co-expression network analysis identified core genes and their transcripts influencing HF development, such as DBI, FZD3, KRT17, ZDHHC21, TMEM79, and HOXC13. Additionally, alternative splicing analysis predicted that the isoforms XM_004004383.4 and XM_012125926.3 of ZDHHC21 might play a crucial role in sheep HF development. This study is a valuable resource for explaining the morphology of normal growth and development of sheep HFs and the genetic foundation of mammalian skin-related traits. It also offers potential insights into factors influencing human hair advancement.

ADAM metallopeptidase with thrombospondin type 1 motif (ADAMTS) are secreted, multi-domain matrix-related zinc endopeptidases that play a role in organogenesis, assembly and degradation of extracellular matrix (ECM), cancer and inflammation. Genome-wide identification and analysis of the bovine ADAMTS gene family has not yet been carried out. In this study, 19 ADAMTS family genes were identified in Bos taurus by genome-wide bioinformatics analysis, and they were unevenly distributed on 12 chromosomes. Phylogenetic analysis shows that the Bos taurus ADAMTS are divided into eight subfamilies, with highly consistent gene structures and motifs within the same subfamily. Collinearity analysis showed that the Bos taurus ADAMTS gene family is homologous to other bovine subfamily species, and many ADAMTS genes may be derived from tandem replication and segmental replication. In addition, based on the analysis of RNA-seq data, we found the expression pattern of ADAMTS gene in different tissues. Meanwhile, we also analyzed the expression profile of ADAMTS gene in the inflammatory response of bovine mammary epithelial cells (BMECs) stimulated by LPS by qRT-PCR. The results can provide ideas for understanding the evolutionary relationship and expression pattern of ADAMTS gene in Bovidae, and clarify the theoretical basis of the function of ADAMTS in inflammation.

肉牛业作为宁夏"六特"产业之一,也是宁夏最新发展战略计划实施的开山之斧.宁夏肉牛种源丰富,既有引入品种,也有地方品种.随着西门塔尔牛和安格斯牛良种扩繁及固原黄牛资源评价与开发利用工作的开展实施,也暴露出一些问题,包括:群体遗传改良基础性工作投入不足、品种繁杂、选育力度低下、种群遗传进展缓慢、育种目标不明确等问题.育种的最终目的是培育出既保留本土特色,又具有"优质-高端"性能的肉牛品种.因此该文对宁夏肉牛种业的发展现状、发展趋势以及存在的问题进行分析总结并提出建议,为进一步推动宁夏肉牛遗传育种产业发展提供参考.

MicroRNAs have been recently reported to act as key regulators of adipogenesis, a multifactorial complex process. One miRNA, miR-302b, is an important regulator of cell proliferation and differentiation and controls cancer development, but we speculate that miR-302b may also regulate bovine adipogenesis. Herein we have evaluated the role of this miRNA in bovine adipocyte differentiation using quantitative Real-Time Polymerase Chain Reaction (qRT-PCR), Oil Red O staining, a dual-luciferase reporter. CDK2 was identified as the target gene of miR-302b, and miR-302b agomir promoted mRNA and protein expression levels of adipocyte-specific genes. In addition, a CCK-8 kit was used to show that miR-302b agomir, but not the negative control, inhibits preadipocyte proliferation. In conclusion, miR-302b promotes bovine preadipocyte differentiation and inhibits proliferation by targeting CDK2.

Background Skeletal muscle is not only an important tissue involved in exercise and metabolism, but also an important part of livestock and poultry meat products. Its growth and development determines the output and quality of meat to a certain extent, and has an important impact on the economic benefits of animal husbandry. Skeletal muscle development is a complex regulatory network process, and its molecular mechanism needs to be further studied. Method We used a weighted co-expression network (WGCNA) and single gene set enrichment analysis (GSEA) to study the RNA-seq data set of bovine tissue differential expression analysis, and the core genes and functional enrichment pathways closely related to muscle tissue development were screened. Finally, the accuracy of the analysis results was verified by tissue expression profile detection and bovine skeletal muscle satellite cell differentiation model in vitro (BSMSCs). Results In this study, Atp2a1, Tmod4, Lmod3, Ryr1 and Mybpc2 were identified as marker genes in muscle tissue, which are mainly involved in glycolysis/gluconeogenesis, AMPK pathway and insulin pathway. The assay results showed that these five genes were highly expressed in muscle tissue and positively correlated with the differentiation of bovine BSMSCs. Conclusions In this study, several muscle tissue characteristic genes were excavated, which may play an important role in muscle development and provide new insights for bovine molecular genetic breeding.

The study aimed to assess differences in proteomic and metabolite profiles in ageing (1, 2, 4, and 6 days at 4 °C) beef exudates and determine their relationship with beef muscle iron metabolism and oxidation. Proteomic and metabolomic analyses identified 877 metabolites and 1957 proteins. The joint analysis identified 24 differential metabolites (DMs) and 56 differentially expressed proteins (DEPs) involved in 15 shared pathways. Ferroptosis was identified as the only iron metabolic pathway, and 4 DMs (l-glutamic acid, arachidonic acid, glutathione and gamma-glutamylcysteine) and 5 DEPs (ferritin, phospholipid hydroperoxide glutathione peroxidase, heme oxygenase 1, major prion protein, and acyl-CoA synthetase long chain family member 4) were involved in iron metabolism by regulating heme and ferritin degradation, Fe2+ and Fe3+ conversion, arachidonic acid oxidation and inactivation of glutathione peroxidase (GPX) 4, leading to increased levels of free iron, ROS, protein and lipid oxidation (P < 0.05). Overall, abnormal iron metabolism during ageing induced oxidative stress in muscle tissue.

Intramuscular fat (IMF) refers to the fat that accumulates between muscle bundles or within muscle cells, whose content significantly impacts the taste, tenderness, and flavor of meat products, making it a crucial economic characteristic in livestock production. However, the intricate mechanisms governing IMF deposition, involving non-coding RNAs (ncRNAs), genes, and complex regulatory networks, remain largely enigmatic. Identifying adipose tissue-specific genes and ncRNAs is paramount to unravel these molecular mysteries. This study, conducted on Jiaxian red cattle, harnessed whole transcriptome sequencing to unearth the nuances of circRNAs and miRNAs across seven distinct tissues. The interplay of these ncRNAs was assessed through differential expression analysis and network analysis. These findings are not only pivotal in unveiling the intricacies of fat deposition mechanisms but also lay a robust foundation for future research, setting the stage for enhancing IMF content in Jiaxian red cattle breeding.

Fibroblast growth factor (FGF) family genes are a class of polypeptide factors with similar structures that play an important role in regulating cell proliferation and differentiation, nutritional metabolism, and neural activity. In previous studies, the FGF gene has been widely studied and analyzed in many species. However, the systematic study of the FGF gene in cattle has not been reported. In this study, 22 FGF genes distributed on 15 chromosomes were identified in the Bos taurus genome and clustered into seven subfamilies according to phylogenetic analysis and conservative domains. Collinear analysis showed that the bovine FGF gene family was homologous to Bos grunniens, Bos indicus, Hybrid-Bos taurus, Bubalus bubalis, and Hybrid-Bos indicus, and tandem replication and fragment replication were the key driving forces for the expansion of the gene family. Tissue expression profiling showed that bovine FGF genes were commonly expressed in different tissues, with FGF1, FGF5, FGF10, FGF12, FGF16, FGF17, and FGF20 being highly expressed in adipose tissue. In addition, real-time fluorescence quantitative PCR (qRT-PCR) detection showed that some FGF genes were differentially expressed before and after adipocyte differentiation, indicating their diverse role in the formation of lipid droplets. This study made a comprehensive exploration of the bovine FGF family and laid a foundation for further study on the potential function in the regulation of bovine adipogenic differentiation.

Intramuscular fat (IMF) content is an important economic factor in beef production. However, knowledge on the key factors controlling bovine IMF is limited. In this study, using weighted gene co-expression network analysis (WGCNA), nine modules were identified and the number of transcripts in these modules ranged from 36 to 3191. Two modules were found to be significantly associated with fat deposition and three genes (TCAP, MYH7, and TNNC1) were further identified by Protein-protein interaction (PPI), which may be the hub genes regulating bovine IMF deposition. In addition, considering the genetic variation, the PCK1 gene was found by functional enrichment analysis of overlapping genes, which was previously reported to be involved in IMF deposition. We noted that the core promoter region of buffalo PCK1 binds to transcription factors involved in lipid metabolism while cattle PCK1 binds transcription factors involved in muscle development. The results suggest that PCK1 participated in IMF deposition of buffalo and cattle in different ways. In summary, gene expression networks and new candidate genes associated with IMF deposition identified in this study. This would lay the foundation for further research into the molecular regulatory mechanisms underlying bovine IMF deposition.

Feed efficiency is a major constraint in the beef industry and has a significant negative correlation with residual feed intake (RFI). RFI is widely used as a measure of feed efficiency in beef cattle and is independent of economic traits such as body weight and average daily gain. However, key traits with commonality or specificity among beef cattle breeds at the same level of RFI have not been reported. Accordingly, the present study hypothesized that signatures associated with feed efficiency would have commonality or specificity in the liver of cattle breeds at the same RFI level. By comparing and integrating liver transcriptome data, we investigated the critical signatures closely associated with RFI in beef cattle using weighted co-expression network analysis, consensus module analysis, functional enrichment analysis and protein network interaction analysis. The results showed that the consensus modules in Angus and Charolais cattle were negatively correlated, and four (turquoise, red, tan, yellow) were significantly positively correlated in Angus liver, while (turquoise, red) were significantly negatively correlated in Charolais liver. These consensus modules were found to be primarily involved in biological processes such as substance metabolism, energy metabolism and gene transcription, which may be one of the possible explanations for the difference in feed efficiency between the two beef breeds. This research also identified five key candidate genes, PLA2G12B, LCAT, MTTP, LCAT, ABCA1 and FADS1, which are closely associated with hepatic lipid metabolism. The present study has identified some modules, genes and pathways that may be the major contributors to the variation in feed efficiency among different cattle breeds, providing a new perspective on the molecular mechanisms of feed efficiency in beef cattle and a research basis for investigating molecular markers associated with feed efficiency in beef cattle.

肉牛产业是我国农业的重要组成部分,也是宁夏回族自治区确定的"六特"产业之一.肉牛产业的发展对宁夏的经济发展起着至关重要的作用.本文从产业链角度出发,综合分析了遗传繁育、疾病防控、饲料营养、养殖育肥、生产加工、销售等肉牛产业发展相关现状和问题,并提出了产业发展建议,为宁夏肉牛产业高质量协调发展提供参考.

Background: Fat is a tissue that not just stores energy and plays a protective role; it is also a vital endocrine organ that generates and integrates signals to influence metabolism. Meanwhile, the excessive accumulation of lipids in adipose tissue can lead to metabolic disturbance and diseases. To date, the complicated molecular mechanisms of bovine adipose tissue are still unknown. This study aimed to identify key genes and functionally enriched pathways in various adipose tissue types. Results: The RNAseq data of 264 samples were downloaded from Gene Expression Omnibus (GEO) and analyzed by weighted gene co-expression network analysis (WGCNA). We identified 19 modules that significantly associated with at least one adipose tissue type. The brown module from GSE39618 was most closely associated with intramuscular fat tissue, which contained 550 genes. These genes were significantly enriched in pathways that related to inflammation and disease, such as TNF signaling pathway, IL-17 signaling pathway, and NF-kappa B signaling pathway. The pink module (GSE39618) that contained 58 genes was most closely associated with omental fat tissue. The turquoise (GSE39618), blue (GSE116775), and yellow (GSE65125) module were most closely associated with subcutaneous fat tissue. Genes in these modules were significantly enriched in pathways related to fat metabolism, such as the PPAR signaling pathway, fatty acid metabolism and PI3K-Akt signaling pathway. At last, key genes for intramuscular fat (PTGS2 and IL6), omental fat (ARHGEF5 and WT1), and subcutaneous fat (KIT, QR6Q1, PKD2L1, etc.) were obtained and verified. In addition, it was found that IL10 and VCAM1 might be potential genes to distinguish adipose and muscle. Conclusion: The study applied WGCNA to generate a landscape of adipose tissue and provide a basis for identifying potential pathways and hub genes of different adipose tissue types.

Methylation and demethylation of histone play a crucial role in regulating chromatin formation and gene expression. The jumonji C (JmjC) domain-containing proteins are demethylases that are involved in regulating epigenetic modification in plants. In our study, the JmjC genes in Triticum aestivum L., Triticum turgidum L., Triticum dicoccoides L., Triticum urartu L., and Aegilops tauschii L. were identified. Phylogenetic relationship and colinearity analysis revealed that the wheat JmjC genes were conserved in A, B, and D subgenomes during evolution. Cis-acting elements analysis showed that elements related to stress response, hormone response, and light response were found in wheat JmjC genes. The expression of JmjC genes was affected by tissue types and developmental stages, and members of the same subfamily tended to have similar expression patterns in wheat. They also showed a unique expression pattern in root during PEG (Polyethylene glycol) treatment. In conclusion, comprehensive analysis indicated that three members (Tr-1A-JMJ2, Tr-1B-JMJ2, and Tr-1D-JMJ2) might be regulated by several hormones and function in the early stages of drought stress, while eight members (Tr-1B-JMJ3, Tr-4B-JMJ1, Tr-7A-JMJ1, etc.) displayed a significantly high expression after 24 h of PEG treatment, indicating a role in the later stages of drought stress. This research presents the first genome-wide study of the JmjC family in wheat, and lays the foundation for promoting the study of their functional characterization in wheat drought resistance.

Abstract Objectives: Serum/glucocorticoid-inducible kinase 1 (SGK1) gene encodes a serine/threonine protein kinase that plays an essential role in cellular stress response and regulation of multiple metabolic processes. However, its role in bovine adipogenesis remains unknown. In this study, we aimed to clarify the role of SGK1 on bovine preadipocyte differentiation. Materials and Methods: Preadipocytes were induced to differentiation to detect the temporal expression pattern of SGK1. Heart, liver, lung, spleen, kidney, muscle and fat tissues were collected to detect its tissue expression profile. Recombinant adenovirus and the lentivirus were packaged for overexpression and knockdown. Oil Red O staining, quantitative real-time PCR, Western blot analysis, Yeast two-hybrid assay, and RNA-seq were performed to study the regulatory mechanism of SGK1. Results: SGK1 showed significantly higher expression in adipose and revealed significantly induced expression in differentiated adipocytes. Furthermore, overexpression of SGK1 greatly promoted adipogenesis and inhibited proliferation, which could be shown by the remarkable increasement of lipid droplet, and the expression levels of adipogenic marker genes and cell cycle-related genes. Inversely, its knockdown inhibited adipogenesis and facilitated proliferation. Mechanistically, SGK1 regulates the phosphorylation and expression of two critical genes located in the downstream of PI3K/Akt signaling pathway, FOXO1/FOXO3, thus promoting adipogenesis and inhibiting proliferation in cattle. Conclusions: SGK1 is required for bovinepreadipocyte proliferation and differentiation, which contributes to a better understanding of fat deposition in cattle.

Background: Improving the intramuscular fat content of beef not only could improve our living standard, but decrease the the risk of the disease from the aspect of human nutrition and diet. Serum/glucocorticoid-inducible kinase 1 (SGK1) is a critical kinase involved in regulating multiple metabolic processes. Results: In the present study we reveal the molecular mechanism by which SGK1 affects the phosphorylation of FOXO1 and FOXO3 thus regulating bovine fat deposition via the PI3K/Akt signaling pathway. SGK1 was characterized primarily in the bovine kidney, where it peaked at day 6 of preadipocyte differentiation. Overexpression of SGK1 in bovine preadipocytes promoted mRNA expression of adipose-specific genes, while cell cycle-related genes were repressed. Adipocyte differentiation-related proteins were not significantly changed, but proliferation-related proteins were markedly inhibited. Moreover, mRNA expression of adipose-specific genes were down-regulated while cell cycle-related genes were up-regulated in response to loss-of-function SGK1. The expression of adipose differentiation-related proteins were significantly inhibited but proliferation-related proteins were not significantly changed. Overexpression of SGK1 in bovine adipocytes significantly changed the gene expression enriched in the PI3K/Akt signaling pathways through RNA-seq. Subsequently, we found that overexpression of SGK1 increased phosphorylation of FOXO1/FOXO3 and reduced protein expression, whereas SGK1 deletion had opposite effects. Overall, we show that overexpression of SGK1 promotes adipogenesis mainly via inhibiting preadipocyte proliferation, whereas the loss-of-function of SGK1 represses adipogenesis mainly through inhibition of adipocyte differentiation. Mechanistically, SGK1 changes the phosphorylation of two key genes located downstream in the PI3K/Akt signaling pathway, FOXO1/FOXO3, thus promoting fat deposition in cattle. Conclusion: These data reveal that SGK1 is a positively regulatory during intramuscular adipogenesis of cattle, which expands the candidates regulating bovine adipogenesis and provides the security for human healthy from the aspect of high-quality beef.

The Wnt family features conserved glycoproteins that play roles in tissue regeneration, animal development and cell proliferation and differentiation. For its functional diversity and importance, this family has been studied in several species, but not in the Bovinae. Herein we identified 19 Wnt genes in cattle, and seven other species of Bovinae, and described their corresponding protein properties. Phylogenetic analysis clustered the 149 Wnt proteins in Bovinae, and 38 Wnt proteins from the human and mouse into 12 major clades. Wnt genes from the same subfamilies shared similar protein motif compositions and exon-intron patterns. Chromosomal distribution and collinearity analysis revealed that they were conservative in cattle and five species of Bovinae. RNA-seq data analysis indicated that Wnt genes exhibited tissue-specific expression in cattle. qPCR analysis revealed a unique expression pattern of each gene during bovine adipocytes differentiation. Finally, the comprehensive analysis indicated that Wnt2B may regulate adipose differentiation by activating FZD5, which is worthy of further study. Our study presents the first genome-wide study of the Wnt gene family in Bovinae, and lays the foundation for further functional characterization of this family in bovine adipocytes differentiation.

Abnormal iron metabolism can cause oxidative stress in broilers, and transport stress (TS) may potentially influence iron metabolism. However, the mechanisms by which TS affects iron metabolism are unclear. This study used quantitative proteome analysis based on tandem mass tag (TMT) to investigate the effects of TS on liver iron metabolism in broilers. Broilers (n = 24) reared under the same conditions were selected randomly into the transported group for 4 h (T2) and non-transported group (T1). Results showed that the serum iron level and total iron-binding capacity of broilers in the T2 were significantly higher than those in the T1 (p < 0.05). The liver iron content of broilers in the T2 (0.498 ± 0.058 mg·gprot−1) was significantly higher than that in the T1 (0.357 ± 0.035 mg·gprot−1), and the iron-stained sections showed that TS caused the enrichment of iron in the liver. We identified 1139 differentially expressed proteins (DEPs). Twelve DEPs associated with iron metabolism were identified, of which eight were up-regulated, and four were down-regulated in T2 compared with T1. Prediction of the protein interaction network for DEPs showed that FTH1, IREB2, and HEPH play vital roles in this network. The results provide new insights into the effects of TS on broilers’ liver iron metabolism.