Protein profiling of plasma proteins in dairy cows with subclinical hypocalcaemia

From Parts to Whole: A Systems Biology Approach to Decoding Milk Fever

Milk fever, or periparturient hypocalcemia, in dairy cows has traditionally been addressed as an acute calcium deficiency, leading to interventions like supplementation and adjustments in dietary cation-anion balance. Although these measures have improved clinical outcomes, milk fever remains a widespread and economically significant issue for the dairy industry. Emerging findings demonstrate that a narrow emphasis on blood calcium concentration overlooks the complex interactions of immune, endocrine, and metabolic pathways. Inflammatory mediators and bacterial endotoxins can compromise hormone-driven calcium regulation and induce compensatory calcium sequestration, thereby worsening both clinical and subclinical hypocalcemia. Recent insights from systems biology illustrate that milk fever arises from nonlinear interactions among various physiological networks, rather than a single deficiency. Consequently, this review contends that a holistic strategy including integrating nutrition, immunology, microbiology, genetics, and endocrinology is vital for comprehensive management and prevention of milk fever. By embracing a multidisciplinary perspective, producers and veterinarians can develop more robust, customized solutions that not only safeguard animal well-being but also bolster profitability. Such an approach promises to meet the evolving demands of modern dairy operations by reducing disease prevalence and enhancing overall productivity. Tackling milk fever through integrated methods may unlock possibilities for improved herd health and sustainable dairy farming.

Metabolomic and Proteomic Profiles Associated With Ketosis in Dairy Cows

Ketosis is a common metabolic disease in dairy cows during early lactation. However, information about the metabolomic and proteomic profiles associated with the incidence and progression of ketosis is still limited. In this study, an integrated metabolomics and proteomics approach was performed on blood serum sampled from cows diagnosed with clinical ketosis (case, ≥ 2.60 mmol/L plasma β-hydroxybutyrate; BHBA) and healthy controls (control, < 1.0 mmol/L BHBA). Samples were taken 2 weeks before parturition and 2 weeks after parturition from 19 animals (nine cases, 10 controls). All serum samples (n = 38) were subjected to Liquid Chromatography-Mass Spectrometry (LC-MS) based metabolomic analysis, and 20 samples underwent Data-Independent Acquisition (DIA) LC-MS based proteomic analysis. A total of 97 metabolites and 540 proteins were successfully identified, and multivariate analysis revealed significant differences in both metabolomic and proteomic profiles between cases and controls. We investigated clinical ketosis-associated metabolomic and proteomic changes using statistical analyses. Correlation analysis of statistically significant metabolites and proteins showed 78 strong correlations (correlation coefficient, R ≥ 0.7) between 38 metabolites and 25 proteins, which were then mapped to pathways using IMPaLA. Results showed that ketosis altered a wide range of metabolic pathways, such as metabolism, metabolism of proteins, gene expression and post-translational protein modification, vitamin metabolism, signaling, and disease related pathways. Findings presented here are relevant for identifying molecular targets for ketosis and biomarkers for ketosis detection during the transition period.

Plasma proteomic profiling and pathway analysis of normal and overconditioned dairy cows during the transition from late pregnancy to early lactation

This study applied a quantitative proteomics approach along with bioinformatics analyses to investigate changes in the plasma proteome of normal and overconditioned dairy cows during the transition period. Fifteen weeks before their anticipated calving date, 38 multiparous Holstein cows were selected based on their current and previous body condition scores (BCS) and allocated to either a high or a normal BCS group (19 cows each). They received different diets until dry-off to reach targeted differences in BCS and back fat thickness (BFT) until dry-off. At dry-off, normal BCS cows had a BCS <3.5 (minimum, 2.75) and BFT <1.2 cm (minimum, 0.58), and the high BCS cows had a BCS >3.75 (maximum, 4.50) and BFT >1.4 cm (maximum, 2.90). The proteomics study used a subset of 5 animals from each group. These cows were selected based on their circulating concentrations of fatty acids (FA) on d 14 postpartum and β-hydroxybutyrate (BHB) on d 21 postpartum, representing the greater or the lower extreme values within their BCS group, respectively. The high BCS subset (HE-HBCS) had 4.50 < BCS > 3.75, FA = 1.17 ± 0.46 mmol/L, and BHB = 2.15 ± 0.42 mmol/L (means ± SD), and the low BCS subset (LE-NBCS) had 3.50 < BCS > 2.75, FA = 0.51 ± 0.28 mmol/L, and BHB = 0.84 ± 0.17 mmol/L. Plasma samples from d -49, +7, and +21 relative to parturition were used for proteome profiling by applying the quantitative tandem mass tags (TMT) approach. Nondepleted plasma samples were subjected to reduction and digestion and then labeled with TMT 10plex reagents. High-resolution liquid chromatography-tandem mass spectrometry analysis of TMT-labeled peptides was carried out, and the acquired spectra were analyzed for protein identification and quantification. In total, 254 quantifiable proteins (criteria: 2 unique peptides and 5% false discovery rate) were identified in the plasma samples. From these, 24 differentially abundant proteins (14 more abundant, 10 less abundant) were observed in the LE-NBCS cows compared with the HE-HBCS cows during the transition period. Plasma α-2-macroglobulins were more abundant in HE-HBCS versus LE-NBCS cows at d +7 and +21. Gene Ontology enrichment analyses of differentially abundant proteins revealed that the acute inflammatory response, regulation of complement activation, protein activation cascade, and regulation of humoral immune response were the most enriched terms in the LE-NBCS group compared with the HE-HBCS group. In addition, we identified 24 differentially abundant proteins (16 in the LE-NBCS group, and 8 in the HE-HBCS group) during the transition period. The complement components C1q and C5 were less abundant, while C3 and C3d were more abundant in LE-NBCS compared with HE-HBCS cows. Overall, overconditioning around calving was associated with alterations in protein pathways related to acute inflammatory response and regulation of complement and coagulation cascades in transition cows.

Clinical Ketosis-Associated Alteration of Gene Expression in Holstein Cows

Ketosis is one of the most prevalent transition metabolic disorders in dairy cows, and has been intrinsically influenced by both genetic and nutritional factors. However, altered gene expression with respective to dairy cow ketosis has not been addressed yet, especially at the genome-wide level. In this study, we recruited nine Holsteins diagnosed with clinical ketosis and ten healthy controls, for which whole blood samples were collected at both prepartum and postpartum. Four groups of blood samples were defined: from cows with ketosis at prepartum (PCK, N = 9) and postpartum (CK, N = 9), respectively, and controls at prepartum (PHC, N = 10) and postpartum (HC, N = 10). RNA-Seq approach was used for investigating gene expression, by which a total of 27,233 genes were quantified with four billion high-quality reads. Subsequently, we revealed 75 and four differentially expressed genes (DEGs) between sick and control cows at postpartum and prepartum, respectively, which indicated that sick and control cows had similar gene expression patterns at prepartum. Meanwhile, there were 95 DEGs between postpartum and prepartum for sick cows, which showed depressed changes of gene expression during this transition period in comparison with healthy cows (428 DEGs). Functional analyses revealed the associated DEGs with ketosis were mainly involved in biological stress response, ion homeostasis, AA metabolism, energy signaling, and disease related pathways. Finally, we proposed that the expression level of STX1A would be potentially used as a new biomarker because it was the only gene that was highly expressed in sick cows at both prepartum and postpartum. These results could significantly help us to understand the underlying molecular mechanisms for incidence and progression of ketosis in dairy cows.

Can neutral dietary cation-anion difference (DCAD) decrease occurrence of clinical periparturient hypocalcaemia in dairy cattle?

BACKGROUND

Adjusting the dietary cation-anion difference (DCAD) is one of the most efficient ways to stimulate calcium homeostasis in periparturient dairy cattle. However, adjusting DCAD to the recommended negative values (-100 to -150 mEq/kg) is associated with decreased food intake and metabolic acidosis. The critical conditions of the animals at peripartum (i.e. drastic hormonal changes, decreased appetite and negative energy balance) can be detrimental to the health, productivity and welfare of the animals if combined with decreased feed intake caused by unpalatable acidogenic salts.

METHODS

In a cross-sectional study, we analysed the ration of eight small to large dairy herds with intensive husbandry systems, including 6949 dry cows. Sodium, potassium, chlorine and sulfur concentrations in the feed were determined and DCAD was calculated. The DCAD of the ration of the farms ranged from -33.5 to +24.7 mEq/kg. Parturient paresis (PP, or milk fever) prevalence was investigated and correlated to DCAD values.

RESULTS

Clinical PP occurrence in the dairies of this investigation on average declined by 87% (ranging from a 97% decline to 5% increase). This indicates that adjusting DCAD at neutral values (0 ± 30 mEq/kg range) may both lower the PP prevalence and increase ration palatability by lowering acidogenic salts in the ration.

CONCLUSIONS

Further research is recommended to investigate the effects of neutral DCAD on subclinical hypocalcaemia and food intake of the cattle.