Persistently high concentrations of β-hydroxybutyrate affect hepatic SOD2 expression and blood SOD activity in high-yielding dairy cows

BACKGROUND

Elevated BHB levels are hypothesized to influence hepatic antioxidant enzyme expression and activity, contributing to oxidative response. However, the impact of BHB between 0.8 and 1.2 mmol/L on these mechanisms remains unclear. We hypothesized that elevated serum BHB levels would influence the hepatic expression of antioxidant genes (SOD1, SOD2, SOD3, and GPX3) and blood antioxidant enzyme activity, contributing to oxidative response. The primary objective was to evaluate the correlation between serum BHB levels, hepatic antioxidant gene expression, and blood antioxidant enzyme activity in high-yielding dairy cows during the postpartum period. The study involved 23 healthy high-yielding Holstein-Friesian dairy cows, divided into experimental (EXP, n = 12) and control (CONT, n = 11) groups based on serum BHB levels during the first three weeks postpartum. The EXP group maintained BHB levels between 0.8 and 1.2 mmol/L, while the CONT group remained below 0.8 mmol/L. All animals were monitored up to 9 weeks postpartum. This cohort study utilized weekly blood samples from 7 days prepartum to 9 weeks postpartum and liver biopsy samples from 4 to 7 weeks postpartum. Serum BHB concentrations, blood SOD and GSH-Px activities, and hepatic expression of SOD1, SOD2, SOD3, and GPX3 genes were analyzed.

RESULTS

The EXP group exhibited a significant increase in hepatic SOD2 expression at 4 weeks postpartum (p < 0.05) and higher blood SOD activity at 6 and 7 weeks postpartum compared to controls. This suggests an oxidative activity response to elevated BHB levels. By week 7, hepatic SOD2 expression began to normalize, indicating a transient response or adaptation. No significant changes were observed in hepatic SOD1, SOD3, or GPX3 expression between groups.

CONCLUSION

Persistently high serum BHB levels in postparturient dairy cows significantly impact hepatic SOD2 expression and blood SOD activity. The specificity of this response, primarily involving SOD2, highlights the complex interplay between metabolic changes and oxidative mechanisms during the transition period. These findings underline the importance of BHB concentration monitoring and suggest potential reevaluation of current BHB thresholds for identifying at-risk cows. Furthermore, SOD2 could potentially serve as an early biomarker.

M1 polarization of hepatic macrophages in cows with subclinical ketosis is an important cause of liver injury

Subclinical ketosis (SCK) is highly prevalent and easily overlooked, with insidious and slow progression of hepatic injury, often characterized by an imbalance in immune homeostasis. In nonruminants, macrophage polarization plays an important regulatory role in hepatic lipid accumulation, fibrosis and inflammatory processes. Thus, we aimed to investigate the status of hepatic macrophage polarization in SCK cows and to corroborate its association with liver injury and inflammation. Twelve Holstein dairy cows (parity, 2-4) were selected, and liver biopsy and blood were collected on the second week postpartum (10-14 d days in milk). On the basis of serum BHBA concentrations., selected cows were categorized into healthy (n = 6; BHBA <1.0 mM) and SCK (n = 6; 1.2 mM ≤ BHBA < 3.0 mM) groups. Serum biochemical parameters were measured using an automatic biochemical analyzer, which indicated higher serum levels of BHBA and NEFA and an upregulation of liver injury indicators (AST, ALT, TP, GLB) in SCK cows compared with healthy cows. ELISA assays revealed that SCK cows displayed systemic low-grade inflammation, as demonstrated by increased serum levels of HP, SAA, TGF-β, IFN-γ, and IL-1β. Liver biopsies revealed pathological histological alterations, hepatic inflammation, and macrophage polarization status. Oil red staining indicated steatosis, while Sirius red staining demonstrated mild extracellular matrix deposition in the liver of SCK cows. The expression of inflammatory response-related proteins (TLR4, p-NFκB, p-I-κB, NLRP3, and Caspase-1) was elevated in the liver of SCK cows, with the increased mean fluorescence intensity of NFκB further confirming the activation of the inflammatory pathway. Furthermore, the levels of pro-inflammatory factors, TNF-α and IFN-γ, were elevated in the tissue homogenate. Macrophage phenotypic changes in SCK cows were further explored based on the results of liver injury and inflammation. Compared with healthy cows, the protein and mRNA abundance of the macrophage marker CD68 in the liver of SCK cows was higher, along with an increased mean fluorescence intensity of CD68. SCK cows also exhibited reduced mRNA expression of the Kupffer cell marker CLEC4F and elevated chemokine levels (CXCL1 and CCL2). As evidenced by greater protein and mRNA abundance of macrophage M1 polarization markers (iNOS, IL-1β, CD86, IL-6, IL-12b, and CCL3), higher fluorescence intensity of iNOS and CD86, and an increased number of CD68+/CD86+-positive cells observed via immunofluorescence, the macrophage polarization phenotype in the liver of SCK cows was predominantly M1. In contrast, the protein and mRNA abundances of M2 polarization markers (CD206, IL-10, and Arg1) were lower in SCK cows, accompanied by a reduced fluorescence intensity of CD206 and a lower number of CD68+/CD206+-positive cells. Overall, the present study revealed that the number of macrophages in liver is enhanced during subclinical ketosis and is dominated by pro-inflammatory macrophages (M1 macrophages). This could partly explain the increased risk of steatosis, fibrosis, and inflammatory response processes in these cows.

Unravelling the Signature Follicular Fluid Metabolites in Dairy Cattle Follicles Growing Under Negative Energy Balance: An In Vitro Approach

The astringent selection criteria for milk-oriented traits in dairy cattle have rendered these animals prone to various metabolic disorders. Postpartum lactational peak and reduced feed intake lead to negative energy balance in cattle. As a compensatory mechanism, cattle start mobilizing fat reserves to meet the energy demand for vital body functions. Consequently, diminished glucose concentrations and elevated ketone body levels lead to poor ovarian function. The impaired follicular development and subpar oocyte quality diminish the conception rates, which poses significant economic repercussions. Follicular fluid is integral to the processes of follicular growth and oocyte development. Hence, the present study was performed to identify potential alterations in metabolites in the follicular fluid under in vitro culture conditions mimicking negative energy balance. Our results revealed nine distinct metabolites exhibiting differential expression in follicular fluid under negative energy balance. The differentially expressed metabolites were predominantly associated with pathways related to amino acid metabolism, lipid metabolism, signal transduction mechanisms, and membrane transport, alongside other biological processes. The identified signature metabolites may be further validated to determine oocyte fitness subjected to in vitro fertilization or embryo production from slaughterhouse source ovaries.

Ileal microbial microbiome and its secondary bile acids modulate susceptibility to nonalcoholic steatohepatitis in dairy goats

BACKGROUND

Liver damage from nonalcoholic steatohepatitis (NASH) presents a significant challenge to the health and productivity of ruminants. However, the regulatory mechanisms behind variations in NASH susceptibility remain unclear. The gut‒liver axis, particularly the enterohepatic circulation of bile acids (BAs), plays a crucial role in regulating the liver diseases. Since the ileum is the primary site for BAs reabsorption and return to the liver, we analysed the ileal metagenome and metabolome, liver and serum metabolome, and liver single-nuclei transcriptome of NASH-resistant and susceptible goats together with a mice validation model to explore how ileal microbial BAs metabolism affects liver metabolism and immunity, uncovering the key mechanisms behind varied NASH pathogenesis in dairy goats.

RESULTS

In NASH goats, increased total cholesterol (TC), triglyceride (TG), and primary BAs and decreased secondary BAs in the liver and serum promoted hepatic fat accumulation. Increased ileal Escherichia coli, Erysipelotrichaceae bacterium and Streptococcus pneumoniae as well as proinflammatory compounds damaged ileal histological morphology, and increased ileal permeability contributes to liver inflammation. In NASH-tolerance (NASH-T) goats, increased ursodeoxycholic acid (UDCA), isodeoxycholic acid (isoDCA) and isolithocholic acid (isoLCA) in the liver, serum and ileal contents were attributed to ileal secondary BAs-producing bacteria (Clostridium, Bifidobacterium and Lactobacillus) and key microbial genes encoding enzymes. Meanwhile, decreased T-helper 17 (TH17) cells and increased regulatory T (Treg) cells proportion were identified in both liver and ileum of NASH-T goats. To further validate whether these key BAs affected the progression of NASH by regulating the proliferation of TH17 and Treg cells, the oral administration of bacterial UDCA, isoDCA and isoLCA to a high-fat diet-induced NASH mouse model confirmed the amelioration of NASH through the TH17 cell differentiation/IL-17 signalling/PPAR signalling pathway by these bacterial secondary BAs.

CONCLUSION

This study revealed the roles of ileal microbiome and its secondary BAs in resilience and susceptibility to NASH by affecting the hepatic Treg and TH17 cells proportion in dairy goats. Bacterial UDCA, isoDCA and isoLCA were demonstrated to alleviate NASH and could be novel postbiotics to modulate and improve the liver health in ruminants. Video Abstract.

Genetic Foundations of Nellore Traits: A Gene Prioritization and Functional Analyses of Genome-Wide Association Study Results

The main goal of this study was to pinpoint functional candidate genes associated with multiple economically important traits in Nellore cattle. After quality control, 1830 genomic regions sourced from 52 scientific peer-reviewed publications were used in this study. From these, a total of 8569 positional candidate genes were annotated for reproduction, 11,195 for carcass, 5239 for growth, and 3483 for morphological traits, and used in an over-representation analysis. The significant genes (adjusted p-values < 0.05) identified in the over-representation analysis underwent prioritization analyses, and enrichment analysis of the prioritized over-represented candidate genes was performed. The prioritized candidate genes were GFRA4, RFWD3, SERTAD2, KIZ, REM2, and ANKRD34B for reproduction; RFWD3, TMEM120A, MIEF2, FOXRED2, DUSP29, CARHSP1, OBI1, JOSD1, NOP58, and LOXL1-AS1 for the carcass; ANKRD34B and JOSD1 for growth traits; and no genes were prioritized for morphological traits. The functional analysis pinpointed the following genes: KIZ (plays a crucial role in spindle organization, which is essential in forming a robust mitotic centrosome), DUSP29 (involved in muscle cell differentiation), and JOSD1 (involved in protein deubiquitination, thereby improving growth). The enrichment of the functional candidate genes identified in this study highlights that these genes play an important role in the expression of reproduction, carcass, and growth traits in Nellore cattle.

Untargeted metabolomics of buffalo urine reveals hydracyrlic acid, 3-bromo-1-propanol and benzyl serine as potential estrus biomarkers

Buffalo is a silent heat animal and doesn't show prominent signs of estrous like cattle so it becomes difficult for farmers to determine the receptivity of the animal based purely on the animal behaviour. India, having a huge population size, needs to produce more milk for the population. Successful artificial insemination greatly depends on the receptivity of the animal. Hence the present study aimed to identify the changes in the metabolome of the buffalo. GC-MS based mass spectrometric analysis was deployed for the determination of estrous by differential expression of metabolites. It was found that hydracrylic acid, 3-bromo-1-propanol and benzyl serine were significantly upregulated in the estrous phase of buffalo (p.value ≤0.05, FC ≥ 2). The pathway enrichment analysis also supported the same as pathways related to amino acid metabolism and fatty acid metabolism were up regulated along with the Warburg effect which is linked to the rapid cell proliferation which might help prepare animals to meet the energy requirement during the estrous. Further analysis of the metabolic biomarkers using ROC analysis also supported these three metabolites as probable biomarkers as they were identified with AUC values of 0.7 or greater. SIGNIFICANCE: The present study focuses on the untargeted metabolomics studies of buffalo urine with special reference to the estrous phase of reproductive cycle. The estrous signals are more prominent in cattle, where animals show clear estrous signals such as mounting and discharge along with vocal signals. Buffalo is a silent heat animal and it becomes difficult for farmers to detect the estrous based on the physical and behavioral signals. Hence the present study focuses on GC-MS based untargeted metabolomics to identify differentially expressed urine metabolites. In this study, hydracrylic acid, 3-bromo-1-propanol and benzyl serine were found to be significantly upregulated in the estrous phase of buffalo (p-value ≤0.05, FC ≥ 2). Further confirmation of the metabolic biomarkers was done using Receiver operating characteristics (ROC) analysis which also supported these three metabolites as probable biomarkers as they had AUC values of 0.7 or greater. Hence, this study will be of prime importance for the people working in the area of animal metabolomics.

Novel lncRNA regulatory elements in milk somatic cells of Holstein dairy cows associated with mastitis

Despite regulatory elements such as long non - coding RNAs representing most of the transcriptome, the functional understanding of long non - coding RNAs in relation to major health conditions including bovine mastitis is limited. This study examined the milk somatic cell transcriptome from udder quarters of 6 Holstein dairy cows to identify differentially expressed long non - coding RNAs using RNA - Sequencing. Ninety - four differentially expressed long non - coding RNAs are identified, 5 of which are previously annotated for gene name and length, 11 are annotated for gene name and 78 are novel, having no gene name or length previously annotated. Significant inflammatory response and regulation of immune response pathways (false discovery rate < 0.05) are associated with the differentially expressed long non - coding RNAs. QTL annotation analysis revealed 31 QTL previously annotated in the genomic regions of the 94 differentially expressed long non - coding RNAs, and the majority are associated with milk traits. This research provides a better understanding of long non - coding RNAs regulatory elements in milk somatic cells, which may enhance current breeding strategies for more adaptable or high mastitis resistant cattle.

N-3 Polyunsaturated Fatty Acids as a Nutritional Support of the Reproductive and Immune System of Cattle-A Review

This paper focuses on the role of n-3 fatty acids as a nutrient crucial to the proper functioning of reproductive and immune systems in cattle. Emphasis was placed on the connection between maternal and offspring immunity. The summarized results confirm the importance and beneficial effect of n-3 family fatty acids on ruminant organisms. Meanwhile, dietary n-3 fatty acids supplementation, especially during the critical first week for dairy cows experiencing their peripartum period, in general, is expected to enhance reproductive performance, and the impact of its supplementation appears to be dependent on body condition scores of cows during the drying period, the severity of the negative energy balance, and the amount of fat in the basic feed ration. An unbalanced, insufficient, or excessive fatty acid supplementation of cows' diets in the early stages of pregnancy (during fetus development) may affect both the metabolic and nutritional programming of the offspring. The presence of the polyunsaturated fatty acids of the n-3 family in the calves' ration affects not only the performance of calves but also the immune response, antioxidant status, and overall metabolism of the future adult cow.

Integrating genome-wide methylation and transcriptome-wide analyses to reveal the genetic mechanism of milk traits in Kazakh horses

Horse Milk has important quantitative characteristics and high economic value. However, the DNA methylation regulators involved in horse milk traits have not been clarified. To explore the important role of genome-wide DNA methylation in regulating equine milk yield, this study systematically investigated the genome-wide DNA methylation profiles of Kazakh horse blood by comparing a high-production group (HP, average daily milk yield of 7.5 kg) and low-production group (LP, average daily milk yield of 3.2 kg) using deep whole-genome bisulfite sequencing. First, both groups showed similar proportions of methylation at CpG sites. Subsequently, we identified 26,677 differential methylated regions (DMRs) of CG, 15 DMRs of CHG, 480 DMRs of CHH and 8268 DMR-related genes (DMGs). GO and KEGG analyses revealed that some DMGs were involved in regulating milk and milk component formation. By combining the WGBS-seq and the previous RNA-seq data, a total of 94 overlapping genes were obtained. Finally, we found that 9 DMGs are likely involved in milk production by Kazakh horses.

Genetic analysis of production traits and body size measurements and their relationships with metabolic diseases in German Holstein cattle

This study sheds light on the genetic complexity and interplay of production, body size, and metabolic health in dairy cattle. Phenotypes for body size-related traits from conformation classification (130,166 animals) and production (101,562 animals) of primiparous German Holstein cows were available. Additionally, 21,992, 16,641, and 7,096 animals were from herds with recordings of the metabolic diseases ketosis, displaced abomasum, and milk fever in first, second, and third lactation. Moreover, all animals were genotyped. Heritabilities of traits and genetic correlations between all traits were estimated and GWAS were performed. Heritability was between 0.240 and 0.333 for production and between 0.149 and 0.368 for body size traits. Metabolic diseases were lowly heritable, with estimates ranging from 0.011 to 0.029 in primiparous cows, from 0.008 to 0.031 in second lactation, and from 0.037 to 0.052 in third lactation. Production was found to have negative genetic correlations with body condition score (BCS; -0.279 to -0.343) and udder depth (-0.348 to -0.419). Positive correlations were observed for production and body depth (0.138-0.228), dairy character (DCH) (0.334-0.422), and stature (STAT) (0.084-0.158). In first parity cows, metabolic disease traits were unfavorably correlated with production, with genetic correlations varying from 0.111 to 0.224, implying that higher yielding cows have more metabolic problems. Genetic correlations of disease traits in second and third lactation with production in primiparous cows were low to moderate and in most cases unfavorable. While BCS was negatively correlated with metabolic diseases (-0.255 to -0.470), positive correlations were found between disease traits and DCH (0.269-0.469) as well as STAT (0.172-0.242). Thus, the results indicate that larger and sharper animals with low BCS are more susceptible to metabolic disorders. Genome-wide association studies revealed several significantly associated SNPs for production and conformation traits, confirming previous findings from literature. Moreover, for production and conformation traits, shared significant signals on Bos taurus autosome (BTA) 5 (88.36 Mb) and BTA 6 (86.40 to 87.27 Mb) were found, implying pleiotropy. Additionally, significant SNPs were observed for metabolic diseases on BTA 3, 10, 14, 17, and 26 in first lactation and on BTA 2, 6, 8, 17, and 23 in third lactation. Overall, this study provides important insights into the genetic basis and interrelations of relevant traits in today's Holstein cattle breeding programs, and findings may help to improve selection decisions.

The Dynamic Transcription Profiles of Proliferating Bovine Ovarian Granulosa When Exposed to Increased Levels of β-Hydroxybutyric Acid

Ketosis is common in high-yield dairy cows. It is a condition that is characterized by the accumulation of serum β-hydroxybutyric acid (BHBA). Both subclinical ketosis and clinical ketosis can compromise the reproductive performance and cause long-lasting negative effects on reproductive efficiency by affecting the proliferation of follicular and granulosa cells. However, the regulatory mechanisms involved in the development of follicular cells and granulosa cells in cows experiencing subclinical ketosis and clinical ketosis remain largely unknown. To investigate the effect of a ketosis-triggered increase in BHBA on bovine follicular granulosa cell development, we detected a significant reduction in the proliferation of granulosa cells (P &lt; 0.05) in the BHBA-1.2 mM and BHBA-2.4 mM groups and a significant increase in the number of granulosa cells in the G1 phase of the cell cycle (P &lt; 0.05). RNA-seq and trend analysis were used to identify differentially expressed genes by comparing three clusters: low-concentration response to 1.2 mM BHBA, high-concentration response to 2.4 mM BHBA, and the similar trend (up or down) response following BHBA concentration increased. GO and KEGG enrichment analyses were performed separately for each cluster. Analysis showed that two novel down-regulated genes (G0S2 and S100A6), which are associated with cell proliferation and cycle progression, were enriched in the low-concentration response to 1.2 mM BHBA. Another differentially expressed gene (PARP), which plays a role in the apoptotic pathway, was enriched in the high-concentration response to 2.4 mM BHBA. We also found that CYP27B1 and CYP17A1, which are associated with Ca2+ homeostasis and estrogen synthesis, were enriched in a similar trend response. In conclusion, we describe the dynamic transcription profiles of granulosa cells under different levels of β-hydroxybutyric stress and report key regulators that may underlie the detrimental effects on the development of follicles and granulosa cells, thus representing potential therapeutic targets to improve fertility in dairy cows with subclinical ketosis or clinical ketosis.

Integration of Multiplied Omics, a Step Forward in Systematic Dairy Research

Due to their unique multi-gastric digestion system highly adapted for rumination, dairy livestock has complicated physiology different from monogastric animals. However, the microbiome-based mechanism of the digestion system is congenial for biology approaches. Different omics and their integration have been widely applied in the dairy sciences since the previous decade for investigating their physiology, pathology, and the development of feed and management protocols. The rumen microbiome can digest dietary components into utilizable sugars, proteins, and volatile fatty acids, contributing to the energy intake and feed efficiency of dairy animals, which has become one target of the basis for omics applications in dairy science. Rumen, liver, and mammary gland are also frequently targeted in omics because of their crucial impact on dairy animals’ energy metabolism, production performance, and health status. The application of omics has made outstanding contributions to a more profound understanding of the physiology, etiology, and optimizing the management strategy of dairy animals, while the multi-omics method could draw information of different levels and organs together, providing an unprecedented broad scope on traits of dairy animals. This article reviewed recent omics and multi-omics researches on physiology, feeding, and pathology on dairy animals and also performed the potential of multi-omics on systematic dairy research.

NEFAs Influence the Inflammatory and Insulin Signaling Pathways Through TLR4 in Primary Calf Hepatocytes in vitro

Transition dairy cows are often in a state of negative energy balance because of decreased dry matter intake and increased energy requirements, initiating lipid mobilization and leading to high serum β-hydroxybutyrate (BHBA) and non-esterified fatty acid (NEFAs) levels, which can induce ketosis and fatty liver in dairy cows. Inflammation and insulin resistance are also common diseases in the perinatal period of dairy cows. What is the relationship between negative energy balance, insulin resistance and inflammation in dairy cows? To study the role of non-esterified fatty acids in the nuclear factor kappa beta (NF-κB) inflammatory and insulin signaling pathways through Toll-like receptor 4 (TLR4), we cultured primary calf hepatocytes and added different concentrations of NEFAs to assess the mRNA and protein levels of inflammatory and insulin signaling pathways. Our experiments indicated that NEFAs could activate the NF-κB inflammatory signaling pathway and influence insulin resistance through TLR4. However, an inhibitor of TLR4 alleviated the inhibitory effects of NEFAs on the insulin pathway. In conclusion, all of these results indicate that high-dose NEFAs (2.4 mM) can activate the TLR4/NF-κB inflammatory signaling pathway and reduce the sensitivity of the insulin pathway through the TLR4/PI3K/AKT metabolic axis.

Integrated Metabolomics and Proteomics Dynamics of Serum Samples Reveals Dietary Zeolite Clinoptilolite Supplementation Restores Energy Balance in High Yielding Dairy Cows

Dairy cows can suffer from a negative energy balance (NEB) during their transition from the dry period to early lactation, which can increase the risk of postpartum diseases such as clinical ketosis, mastitis, and fatty liver. Zeolite clinoptilolite (CPL), due to its ion-exchange property, has often been used to treat NEB in animals. However, limited information is available on the dynamics of global metabolomics and proteomic profiles in serum that could provide a better understanding of the associated altered biological pathways in response to CPL. Thus, in the present study, a total 64 serum samples were collected from 8 control and 8 CPL-treated cows at different time points in the prepartum and postpartum stages. Labelled proteomics and untargeted metabolomics resulted in identification of 64 and 21 differentially expressed proteins and metabolites, respectively, which appear to play key roles in restoring energy balance (EB) after CPL supplementation. Joint pathway and interaction analysis revealed cross-talks among valproic acid, leucic acid, glycerol, fibronectin, and kinninogen-1, which could be responsible for restoring NEB. By using a global proteomics and metabolomics strategy, the present study concluded that CPL supplementation could lower NEB in just a few weeks, and explained the possible underlying pathways employed by CPL.

Single-step genomic best linear unbiased predictor genetic parameter estimations and genome-wide associations for milk fatty acid profiles, interval from calving to first insemination, and ketosis in Holstein cattle

Milk fatty acids (FA) have been suggested as biomarkers for early-lactation metabolic diseases and for female fertility status. The aim of the present study was to infer associations between FA, the metabolic disorder ketosis (KET), and the interval from calving to first insemination (ICF) genetically and genomically. In this regard, we focused on a single-step genomic BLUP approach, allowing consideration of genotyped and ungenotyped cows simultaneously. The phenotypic data set considered 38,375 first-lactation Holstein cows, kept in 45 large-scale co-operator herds from 2 federal states in Germany. The calving years for these cows were from 2014 to 2017. Concentrations in milk from the first official milk recording test-day for saturated, unsaturated (UFA), monounsaturated (MUFA), polyunsaturated, palmitic, and stearic (C18:0) FA were determined via Fourier-transform infrared spectroscopy. Ketosis was defined as a binary trait according to a veterinarian diagnosis key, considering diagnoses within a 6-wk interval after calving. A subset of 9,786 cows was genotyped for 40,989 SNP markers. Variance components and heritabilities for all Gaussian distributed FA and for ICF, and for binary KET were estimated by applying single-step genomic BLUP single-trait linear and threshold models, respectively. Genetic correlations were estimated in series of bivariate runs. Genomic breeding values for the single-step genomic BLUP estimations were dependent traits in single-step GWAS. Heritabilities for FA were moderate in the range from 0.09 to 0.20 (standard error = 0.02-0.03), but quite small for ICF (0.08, standard error = 0.01) and for KET (0.05 on the underlying liability scale, posterior standard deviation = 0.02). Genetic correlations between KET and UFA, MUFA, and C18:0 were large (0.74 to 0.85, posterior standard deviation = 0.14-0.19), and low positive between KET and ICF (0.17, posterior standard deviation = 0.22). Genetic correlations between UFA, MUFA, and C18:0 with ICF ranged from 0.34 to 0.46 (standard error = 0.12). In single-step GWAS, we identified a large proportion of overlapping genomic regions for the different FA, especially for UFA and MUFA, and for saturated and palmitic FA. One identical significantly associated SNP was identified for C18:0 and KET on BTA 15. However, there was no genomic segment simultaneously significantly affecting all trait categories ICF, FA, and KET. Nevertheless, some of the annotated potential candidate genes DGKA, IGFBP4, and CXCL8 play a role in lipid metabolism and fertility mechanisms, and influence production diseases in early lactation. Genetic and genomic associations indicate that Fourier-transform infrared spectroscopy FA concentrations in milk from the first official test-day are valuable predictors for KET and for ICF.