Abstract: The Kazakh mare, an indigenous breed of Xinjiang, exhibits strong adaptability to arid and cold conditions while maintaining relatively stable milk production under low-input extensive farming systems. However, its genetic improvement has been constrained by traditional management practices. Results: In this study, we monitored milk yield and milk composition over a 105-day lactation period and recorded 15 phenotypic traits. Milk yield was significantly correlated with body length, teat diameter, and teat length. The high-yield (HY) versus low-yield (LY) and high-fat (HF) versus low-fat (LF) comparisons identified 286 and 627 differentially expressed genes (DEGs), respectively. Several candidate genes were identified, including PMP22, FAM83A, HSD17B3, AGPAT4, SLC50A1, and ERBB3, which were associated with pathways including PI3K-Akt signaling, MAPK signaling, and triglyceride metabolism. High-yield mares showed metabolic differences characterized by enrichment of pathways related to the tricarboxylic acid (TCA) cycle, suggesting altered energy and intermediary metabolism involving carbohydrates, lipids, and amino acids. Metabolites associated with these differences included glycerone, α-D-glucose, D-galactose, glycerol, L-histidine, and anserine. In addition, machine learning analysis identified GLDC as a candidate gene potentially associated with milk fat percentage, possibly through its association with histidine. However, this relationship requires further validation. Conclusions: Using peripheral blood samples, this study integrated differential expression analysis, mixed linear models, and machine learning approaches to identify candidate genes and metabolites associated with lactation performance in Kazakh mares. The results provide preliminary insights into molecular and metabolic features associated with lactation traits in this breed. These findings may serve as a reference for future molecular breeding and nutritional studies.
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
Overview
This research aimed to identify genes and metabolites linked to milk production traits in Kazakh mares, a hardy horse breed adapted to harsh environments.
Using blood samples and multi-omics data combined with machine learning, the study discovered candidate molecular markers and pathways influencing lactation performance.
Background and Significance
Breed characteristics: Kazakh mares are native to Xinjiang and known for their resilience to arid and cold climates, as well as their ability to maintain milk production even in low-input farming.
Challenges: Traditional management practices limit genetic improvement efforts for milk yield and quality in this breed.
Purpose: This study aims to uncover genetic and metabolic factors underlying milk yield and composition to aid future breeding and nutritional intervention strategies.
Study Design and Data Collection
Lactation monitoring: Milk yield and composition were measured over a 105-day lactation period.
Phenotypic traits: A total of 15 traits were recorded, including body length, teat diameter, and teat length.
Correlations: Milk yield showed significant positive correlations with body length and teat dimensions, indicating these traits relate to production capacity.
Genomic and Transcriptomic Analysis
Group comparisons: Mares were grouped into high-yield (HY) vs. low-yield (LY) and high-fat (HF) vs. low-fat (LF) milk producers.
Differential gene expression: Identified 286 DEGs between HY and LY groups and 627 DEGs between HF and LF groups.
Candidate genes: Key genes associated with lactation traits included:
PMP22 (Peripheral myelin protein 22)
FAM83A (Family with sequence similarity 83 member A)
Pathway enrichment: These genes were involved in biological pathways such as:
PI3K-Akt signaling pathway (regulates cell growth and metabolism)
MAPK signaling pathway (involved in cell proliferation and differentiation)
Triglyceride metabolism (important for milk fat synthesis)
Metabolomic Findings
Energy metabolism: High-yield mares exhibited altered metabolic profiles indicating enhanced activity in energy-generating pathways.
TCA cycle: Enrichment in tricarboxylic acid cycle intermediates suggests shifts in energy and intermediary metabolism.
Specific metabolites associated with lactation traits:
Glycerone
α-D-glucose
D-galactose
Glycerol
L-histidine (an amino acid)
Anserine (a dipeptide related to antioxidant functions)
Machine Learning Insights
Analytic approach: Machine learning models were applied to the multi-omics data to identify potential gene-metabolite relationships influencing milk traits.
Key candidate gene: GLDC (Glycine decarboxylase) was highlighted as potentially linked to milk fat percentage.
Putative mechanism: The association between GLDC and milk fat may be mediated by its relationship with histidine metabolism, though this requires further experimental validation.
Conclusions and Implications
The integrative multi-omics approach successfully identified genes and metabolites correlated with variation in milk yield and fat content in Kazakh mares.
Results provide molecular insights into lactation performance traits and highlight candidate pathways that could be targets for genetic selection or nutritional optimization.
This foundational work supports future molecular breeding programs aimed at improving milk production in indigenous horse breeds adapted to challenging environments.
Using peripheral blood as a sampling source demonstrates a non-invasive method to study lactation biology in large animals.
Cite This Article
APA
Meng C, Luo P, Ren W, Xie X, Zeng Y, Wang J, Yao X, Meng J.
(2026).
Identification of candidate genes and metabolites associated with lactation performance in Kazakh mares using blood multi-omics and machine learning.
BMC Genomics, 27(1), 791.
https://doi.org/10.1186/s12864-026-13131-w
College of Animal Science, Equine Industry Research Institute, Xinjiang Agricultural University, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China.
College of Animal Science, Equine Industry Research Institute, Xinjiang Agricultural University, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China.
Xinjiang Key Laboratory of Equine Breeding and Exercise Physiology, Urumqi, Xinjiang, 830052, China.
College of Animal Science, Equine Industry Research Institute, Xinjiang Agricultural University, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China.
Xinjiang Key Laboratory of Equine Breeding and Exercise Physiology, Urumqi, Xinjiang, 830052, China.
Wang, Jianwen
College of Animal Science, Equine Industry Research Institute, Xinjiang Agricultural University, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China.
Xinjiang Key Laboratory of Equine Breeding and Exercise Physiology, Urumqi, Xinjiang, 830052, China.
Yao, Xinkui
College of Animal Science, Equine Industry Research Institute, Xinjiang Agricultural University, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China.
Xinjiang Key Laboratory of Equine Breeding and Exercise Physiology, Urumqi, Xinjiang, 830052, China.
Meng, Jun
College of Animal Science, Equine Industry Research Institute, Xinjiang Agricultural University, Xinjiang Agricultural University, Urumqi, Xinjiang, 830052, China. junm86@xjau.edu.cn.
Xinjiang Key Laboratory of Equine Breeding and Exercise Physiology, Urumqi, Xinjiang, 830052, China. junm86@xjau.edu.cn.
MeSH Terms
Animals
Lactation / genetics
Female
Horses / genetics
Horses / blood
Horses / metabolism
Horses / physiology
Machine Learning
Multiomics
Phenotype
Milk / metabolism
Milk / chemistry
Gene Expression Profiling
Metabolome
Genomics
Grant Funding
XJ2026G118 / the Study on the Effect of Mare Milk-Derived Peptides on High-Fat Diet-Induced Metabolic Disorders and Its Regulatory Mechanism
XJARS-11 / Xinjiang Uygur Autonomous Region Dairy Industry Technology System Project
2024B02013-2 / Construction of equine milk probiotic library and R&D and demonstration of functional equine milk products
2022A02013-1 / the Major Science and Technology Project of the Xinjiang Uygur Autonomous Region
Conflict of Interest Statement
Declarations. Ethics approval and consent to participate: The experimental protocol was approved by the Institutional Animal Care and Use Committee of Xinjiang Agricultural University (Urumqi, China) under approval number 2023020. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.
References
This article includes 94 references
Fuquay JW, McSweeney PL, Fox PF. Encyclopedia of Dairy Sciences. Int Dairy J. 2012;24:48.
Kendal MB, Toyin L, Amy E, Esmaeel G, Hildah N, Amy MC. Evaluation of dietary protein and amino acid requirements: a systematic review. Am J Clin Nutr 2025;122:285–305.
Fu Y, Shen N, Wang S, Liu Y, Peng P, Shi L. Integrating transcriptomic and metabolomic profiles of primiparous Holstein cows across multiple lactation periods reveals the regulatory mechanism underlying milk component traits. J Dairy Sci 2025;108:10377–10390.
Zhu L, Feng J, Cai J, Liu J, Wang D. Integrated analysis of cellular RNA and metabolome to understand the small molecules bio-synthesis in milk. Food Biosci 2025;68:106739.
Zhang C, Liu H, Jiang X, Zhang Z, Hou X, Wang Y. An integrated microbiome-and metabolome-genome-wide association study reveals the role of heritable ruminal microbial carbohydrate metabolism in lactation performance in Holstein dairy cows. Microbiome 2024;12:232.
Zhu L, Feng J, Cai J, Liu J, Wang D. Integrated analysis of cellular RNA and metabolome to understand the small molecules bio-synthesis in milk. Food Bioscience 2025;68:106739.
Guan S, Xu Z, Yang T, Zhang Y, Zheng Y, Chen T. Identifying potential targets for preventing cancer progression through the PLA2G1B recombinant protein using bioinformatics and machine learning methods. Int J Biol Macromol 2024;276:133918.
Cui Z, Gong G. The effect of machine learning regression algorithms and sample size on individualized behavioral prediction with functional connectivity features. NeuroImage 2018;178:622–37.
Ao Y, Li H, Zhu L, Ali S, Yang Z. The linear Random Forest algorithm and its advantages in machine learning assisted logging regression modeling. J Pet Sci Eng 2019;174:776–89.
Cantor E, Guauque-Olarte S, León R, Chabert S, Salas R. Knowledge-slanted Random Forest method for high-dimensional data and small sample size with a feature selection application for gene expression data. BioData Min 2024;17:34.
Wang Y, Jin C, Ma L, Liu X. A robust TabNet-based multi-classification algorithm for infrared spectral data of Chinese herbal medicine with high-dimensional small samples. J Pharm Biomed Anal 2024;242:116031.
Achieng KO. Modelling of soil moisture retention curve using machine learning techniques: Artificial and deep neural networks vs support vector regression models. Comput Geosci 2019;133:104320.
Bauman DE, Currie WB. Partitioning of nutrients during pregnancy and lactation: a review of mechanisms involving homeostasis and homeorhesis. J Dairy Sci 1980;63:1514–29.
Toghiani S, VanRaden PM, VandeHaar MJ, Baldwin RL, Weigel KA, White HM. Dry matter intake in US Holstein cows: Exploring the genomic and phenotypic impact of milk components and body weight composite. J Dairy Sci 2024;107:7009–21.
Mucha S, Mrode R, Coffey M, Kizilaslan M, Desire S, Conington J. Genome-wide association study of conformation and milk yield in mixed-breed dairy goats. J Dairy Sci 2018;101:2213–25.
Yang DB, Xu YC, Wang DH, Speakman JR. Effects of reproduction on immuno-suppression and oxidative damage, and hence support or otherwise for their roles as mechanisms underpinning life history trade-offs, are tissue and assay dependent. J Exp Biol 2013;216:4242–50.
Viitala SM, Schulman NF, de Koning DJ, Elo K, Kinos R, Virta A. Quantitative trait loci affecting milk production traits in Finnish Ayrshire dairy cattle. J Dairy Sci 2003;86:1828–36.
Snipes GJ, Suter U, Welcher AA, Shooter EM. Characterization of a novel peripheral nervous system myelin protein (PMP-22/SR13). J Cell Biol 1992;117:225–38.
Mobley CK, Myers JK, Hadziselimovic A, Ellis CD, Sanders CR. Purification and initiation of structural characterization of human peripheral myelin protein 22, an integral membrane protein linked to peripheral neuropathies. Biochemistry 2007;46:11185–95.
Du C, La ALTZ, Gao S, Gao W, Ma L, Bu D. Hepatic Transcriptome Reveals Potential Key Genes Contributing to Differential Milk Production. Genes 2024;15:1229.
Arlt W, Auchus RJ, Miller WL. Thiazolidinediones but not metformin directly inhibit the steroidogenic enzymes P450c17 and 3β-hydroxysteroid dehydrogenase. J Biol Chem 2001;276:16767–71.
Kang DH, Kim MJ, Mohamed EA, Kim DS, Jeong JS, Kim SY. Regulation of uterus and placenta remodeling under high estradiol levels in gestational diabetes mellitus models. Biol Reprod 2023;109:215–26.
Sawyer G, Fulkerson W, Martin G, Gow C. Artificial induction of lactation in cattle: initiation of lactation and estrogen and progesterone concentrations in milk. J Dairy Sci 1986;69:1536–44.
Gritsienko Y, Gill M, Karatieievа O. Connection between gene markers with milk production traits of Ukrainian dairy cows. Online J Anim Feed Res 2022;12:302–13.
Tong J, Thompson I, Zhao X, Lacasse P. Effect of 17β-estradiol on milk production, hormone secretion, and mammary gland gene expression in dairy cows. J Dairy Sci 2018;101:2588–601.
Santos D, Cole J, Null D, Byrem T, Ma L. Genetic and nongenetic profiling of milk pregnancy-associated glycoproteins in Holstein cattle. J Dairy Sci 2018;101:9987–10000.
Yurchenko AA, Deniskova TE, Yudin NS, Dotsev AV, Khamiruev TN, Selionova MI. High-density genotyping reveals signatures of selection related to acclimation and economically important traits in 15 local sheep breeds from Russia. BMC Genomics 2019;20:294.
Cao M, Shi L, Peng P, Han B, Liu L, Lv X. Determination of genetic effects and functional SNPs of bovine HTR1B gene on milk fatty acid traits. BMC Genomics 2021;22:575.
Suárez-Trujillo A, Argüello A, Rivero M, Capote J, Castro N. Differences in distribution of serotonin receptor subtypes in the mammary gland of sheep, goats, and cows during lactation and involution. J Dairy Sci 2019;102:2703–7.
Zhang C, Chen H, Wang Y, Zhang R, Lan X, Lei C. Serotonin receptor 1B (HTR1B) genotype associated with milk production traits in cattle. Res Vet Sci 2008;85:265–8.
Koeberle A, Shindou H, Harayama T, Yuki K, Shimizu T. Polyunsaturated fatty acids are incorporated into maturating male mouse germ cells by lysophosphatidic acid acyltransferase 3. FASEB J 2012;26:169–80.
Harmar AJ, Fahrenkrug J, Gozes I, Laburthe M, May V, Pisegna JR. Pharmacology and functions of receptors for vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide: IUPHAR review 1. Br J Pharmacol 2012;166:4–17.
Dolatshad H, Campbell E, O’hara L, Maywood E, Hastings M, Johnson M. Developmental and reproductive performance in circadian mutant mice. Hum Reprod 2006;21:68–79.
Cheng Z, Little M, Ferris C, Takeda H, Ingvartsen K, Crowe M. Influence of the concentrate inclusion level in a grass silage-based diet on hepatic transcriptomic profiles in Holstein-Friesian dairy cows in early lactation. J Dairy Sci 2023;106:5805–24.
Ayalew W, Wu X, Tarekegn GM, Sisay Tessema T, Naboulsi R, Van Damme R. Whole genome scan uncovers candidate genes related to milk production traits in Barka cattle. Int J Mol Sci 2024;25:6142.
Zhao J, Shi C, Kamalibieke J, Gong P, Mu Y, Zhu L. Whole genome and transcriptome analyses in dairy goats identify genetic markers associated with high milk yield. Int J Biol Macromol 2025;292:139192.
Asadi Yousefabad SL, Tamadon A, Rahmanifar F, Jafarzadeh Shirazi MR, Sabet Sarvestani F, Tanideh N. Lactation effect on the mRNAs expression of RFRP-3 and KiSS-1 in dorsomedial and arcuate nuclei of the rat hypothalamus. Physiol Pharmacol 2013;17:277–85.
Han B, Lin S, Ye W, Chen A, Liu Y, Sun D. COL6A1 Promotes Milk Production and Fat Synthesis Through the PI3K-Akt/Insulin/AMPK/PPAR Signaling pathways in Dairy Cattle. Int J Mol Sci 2025;26:2255.
Yang Y, Wang Z, Ge H, Wang B, Xing P, Wang N. Leptin signaling promotes milk fat synthesis via PI3K/AKT/mTOR/SREBP1 in mammary gland of dairy cow. J Dairy Res 2024;91:433–44.
Shao Y, Huang J, Wei M, Fan L, Shi H, Shi H. Soybean isoflavone promotes milk yield and milk fat yield through the ERα-mediated Akt/mTOR pathway in dairy goats. J Anim Sci 2024;102:352.
He Q, Gao L, Zhang F, Yao W, Wu J, Song N. The FoxO1-ATGL axis alters milk lipolysis homeostasis through PI3K/AKT signaling pathway in dairy goat mammary epithelial cells. J Anim Sci 2023;101:286.
Wang W, Wang S, Wang H, Zheng E, Wu Z, Li Z. Protein Dynamic Landscape during Mouse Mammary Gland Development from Virgin to Pregnant, Lactating, and Involuting Stages. J Agric Food Chem 2024;72:7546–57.
Wang Y, Liang Y, Xia Y, Wang M, Zhang H, Li M. Identification and characterization of long non-coding RNAs in mammary gland tissues of Chinese Holstein cows. J Anim Sci 2024;102:128.
Saleem A, Mumtaz PT, Saleem S, Manzoor T, Taban Q, Dar MA. Comparative transcriptome analysis of E. coli & Staphylococcus aureus infected goat mammary epithelial cells reveals genes associated with infection. Int Immunopharmacol 2024;126:111213.
Zhang J, Xie L, Li H, Li S, Gao X, Zhang M. Selenomethionine Promotes Milk Protein and Fat Synthesis and Proliferation of Mammary Epithelial Cells through the GPR37-mTOR-S6K1 Signaling. J Agric Food Chem 2024;72:19505–16.
Gu JY, Li XB, Liao GQ, Wang TC, Wang ZS, Jia Q. Comprehensive analysis of phospholipid in milk and their biological roles as nutrients and biomarkers. Crit Rev Food Sci Nutr 2025;65:2261–80.
Benedet A, Manuelian C, Zidi A, Penasa M, De Marchi M. Invited review: β-hydroxybutyrate concentration in blood and milk and its associations with cow performance.. Animal 2019;13:1676–89.
Grassian AR, Parker SJ, Davidson SM, Divakaruni AS, Green CR, Zhang X. IDH1 mutations alter citric acid cycle metabolism and increase dependence on oxidative mitochondrial metabolism.. Cancer Res 2014;74:3317–31.
Sun HZ, Shi K, Wu XH, Xue MY, Wei ZH, Liu JX. Lactation-related metabolic mechanism investigated based on mammary gland metabolomics and 4 biofluids’ metabolomics relationships in dairy cows.. BMC Genomics 2017;18:936.
Zhang Q, Koser SL, Bequette BJ, Donkin SS. Effect of propionate on mRNA expression of key genes for gluconeogenesis in liver of dairy cattle.. J Dairy Sci 2015;98:8698–709.
Pyke GH, Ehrlich PR. Biological collections and ecological/environmental research: a review, some observations and a look to the future.. Biol Rev 2010;85:247–66.
Feng X, Ma R, Wang Y, Tong L, Wen W, Mu T. Non-targeted metabolomics identifies biomarkers in milk with high and low milk fat percentage.. Food Res Int 2024;179:113989.
Zhang H, Wang Y, Hu L, Cong J, Xu Z, Chen X. Potential role of lauric acid in milk fat synthesis in Chinese Holstein cows based on integrated analysis of ruminal microbiome and metabolome.. Animals 2024;14:1493.
Zhang F, Zhao Y, Wang Y, Wang H, Guo Y, Xiong B. Effects of calcium propionate on milk performance and serum metabolome of dairy cows in early lactation.. Anim Feed Sci Technol 2022;283:115185.
Lopez C, Briard BV, Menard O, Rousseau F, Pradel P, Besle JM. Phospholipid, sphingolipid, and fatty acid compositions of the milk fat globule membrane are modified by diet.. J Agric Food Chem 2008;56:5226–36.
Liu Z, Li C, Pryce J, Rochfort S. Comprehensive characterization of bovine milk lipids: Phospholipids, sphingolipids, glycolipids, and ceramides.. J Agric Food Chem 2020;68:6726–38.
Liu R, Zeng LW, Gong R, Yuan F, Shu HB, Li S. mTORC1 activity regulates post-translational modifications of glycine decarboxylase to modulate glycine metabolism and tumorigenesis.. Nat Commun 2021;12:4227.
Chang G, Wang L, Ma N, Zhang W, Zhang H, Dai H. histamine activates inflammatory response and depresses casein synthesis in mammary gland of dairy cows during SARA.. BMC Vet Res 2018;14:168.