Changes of the liver metabolome following an intravenous lipopolysaccharide injection in Holstein cows supplemented with dietary carnitine

Longitudinal characterization of the metabolome of dairy cows transitioning from one lactation to the next: Investigations in fecal samples

The fecal metabolome comprises metabolites that are excreted or not absorbed by the animal. This study examined the changes in the fecal metabolome of dairy cows from the end of one lactation period, through the dry period, and into the subsequent lactation. Twelve Holstein cows (BW = 745 ± 71 kg, BCS = 3.43 ± 0.66) were housed in a tiestall barn from 7 wk before to 15 wk after parturition, with dry-off occurring approximately 6 wk before the expected calving date (mean dry-off time = 42 d). Fecal samples were taken at wk -7, -5, -1, +1, +5, +10, and +15 relative to calving. Targeted metabolomics identified a total of 93 metabolites, including AA, biogenic amines, bile acids (BA), acylcarnitines (AcylCN), and some phospholipids. Principal component analysis (PCA) revealed clear metabolic shifts that showed a clear separation between the samples from the dry period and the samples from the end, early, and middle of lactation, indicating significant changes in the metabolic profiles in the feces. The transition from the dry period (wk -5, -1 relative to calving) to lactation (wk +1, +5, +10, +15, and -7 relative to calving) is characterized by an increase in fecal AA and metabolites, such as Glu, Met, β-alanine, and methionine sulfoxide, reflecting a shift in nitrogen metabolism to support increased protein metabolism for milk production. Higher concentrations of polyamines, such as spermidine and putrescine, were observed postpartum, indicating increased cell growth and improved tissue regeneration. Elevated gamma-aminobutyric acid levels during lactation indicate increased microbial activity driven by a nutrient-rich diet. Results showed significant adjustments in BA profiles as cows transitioned into lactation. Deoxycholic acid remained the predominant BA in feces, reflecting ongoing microbial transformation, whereas glycine- and taurine-conjugated BA increased postpartum, suggesting improved enterohepatic circulation and lipid absorption. Fecal AcylCN showed dynamic shifts with elevated levels during late gestation, a decrease in the dry period, and an increase postpartum, indicating increased fatty acid oxidation to meet energy demands. Results showed that phosphatidylcholines decreased prepartum but increased after calving. This indicates shifts in lipid metabolism reflecting energy requirements in lactation and suggests that fecal lipid composition is an indicator of metabolic adaptations in dairy cows. In particular, PCA revealed considerable overlap in the fecal metabolite profiles of multiparous and primiparous cows, indicating similar metabolic profiles. This was also confirmed by volcano plots, which showed no significant differences in fecal metabolism between the 2 groups across different weeks relative to calving (wk -7, -5, -1, +1, +5, +10, and +15). Overall, these results emphasize the complex interactions between dietary factors, liver and gastrointestinal function, and the gut microbiome in shaping the fecal metabolite profile of dairy cows. These results underscore the value of this data set in advancing the application of fecal metabolome profiling to investigate metabolic changes during critical transitions in the lactation cycle of dairy cows.

Effects of Postpartal Relative Body Weight Change on Production Performance, Serum Biomarkers, and Fecal Microbiota in Multiparous Holstein Cows

This study aimed to determine effects of postpartal relative body weight change (PRBWC) on production performance, serum biomarkers, and the relation between PRBWC and gastrointestinal microbiota. A total of 59 multiparous cows participated in this research. Every cow's PRBWC was calculated by the following equation: PRBWC = (BW21 - BW0)/BW0 × 100%, in which BW21 refers to body weight on Day 21 post-calving and BW0 refers to body weight on the day of parturition. Among the 59 enrolled cows, cows with the top 21 ranked PRBWC values were categorized into the high PRBWC (H-PRBWC) group; cows with the bottom 21 ranked PRBWC values were categorized into the low PRBWC (L-PRBWC) group. PRBWC did not have significant influences on average daily milk yield (ADMY). However, on Day 21, cows in the H-PRBWC group displayed significantly higher body weight (BW) and body condition scores (BCS) (BW, p = 0.02; BCS, p < 0.01). Additionally, levels of serum glucose (GLU) and albumin (ALB) were significantly higher in the H-PRBWC group on Day 21 (GLU, p = 0.05; ALB, p < 0.01), while the lipopolysaccharide-binding protein (LBP) level was significant lower (p = 0.03). Moreover, the microbiota of fecal samples on Day 0 (FE0) differed notably between groups, as evidenced by various alpha diversity indices, including Shannon (p = 0.02), Simpson (p = 0.03), Pielou_e (p = 0.02), and principal coordinate analysis (p = 0.002). The relative abundances of Monoglobus, norank_f__UCG-010, and Christensenellaceae_R-7_group were significantly higher in the H-PRBWC group (p < 0.05), while the relative abundances of Clostridium_sensu_stricto_1, Turicibacter, and Romboutsia were significantly lower (p < 0.05). Pathways related to amino acid biosynthesis were significantly enriched in the FE0 of the H-PRBWC group, while pathways involved in carbohydrate metabolism were significantly upregulated in the FE0 of the L-PRBWC group. This study argues the potential of PRBWC to describe alteration of energy status in the postpartum, evidenced by production performance, serum biomarkers, and the fecal microbiota.

Plasma and milk metabolomics revealed changes in amino acid metabolism in Holstein dairy cows under heat stress

Our understanding of metabolic alterations triggered by heat stress is incomplete, which limits the designing of nutritional strategies to mitigate negative productive and health effects. Thus, this study aimed to explore the metabolic responses of heat-stressed dairy cows to dietary supplementation with vitamin D3/Ca and vitamin E/Se. Twelve multiparous Holstein cows were enrolled in a split-plot Latin square design with two distinct vitamin E/Se supplementation levels, either at a low (ESe-, n = 6, 11.1 IU/kg vitamin E and 0.55 mg/kg Se) or a high dose (ESe+, n = 6 223 IU/kg vitamin E and 1.8 mg/kg Se) as the main plot. Treatment subplots, arranged in a replicated 3 × 3 Latin square design, comprised heat challenge (Temperature Humidity Index, THI: 72.0-82.0) supplemented with different levels of vitamin D3/Ca: either low (HS/DCa-, 1 012 IU/kg and 0.73%, respectively) or high (HS/DCa+, 3 764 IU/kg and 0.97%, respectively), and a pair-fed control group in thermoneutrality (THI = 61.0-64.0) receiving the low dose of vitamin D3/Ca (TN). The liquid chromatography-mass spectrometry-based metabolome profile was determined in blood plasma and milk sampled at the beginning (day 0) and end (day 14) of each experimental period. The results were analyzed for the effect of (1) TN vs. HS/ESe-/DCa-, and (2) the vitamin E/Se and vitamin D3/Ca supplementation. No group or group × day effects were detected in the plasma metabolome (false discovery rate, FDR > 0.05), except for triglyceride 52:2 being higher (FDR = 0.03) on day 0 than 14. Taurine, creatinine and butyryl-carnitine showed group × day interactions in the milk metabolome (FDR ≤ 0.05) as creatinine (+22%) and butyryl-carnitine (+190%) were increased (P < 0.01) on day 14, and taurine was decreased (-65%, P < 0.01) on day 14 in the heat stress (HS) cows, compared with day 0. Most compounds were unaffected by vitamin E/Se or vitamin D3/Ca supplementation level or their interaction (FDR > 0.05) in plasma and milk, except for milk alanine which was lower (-69%, FDR = 0.03) in the E/Se+ groups, compared with E/Se-. Our results indicated that HS triggered more prominent changes in the milk than in the plasma metabolome, with consistent results in milk suggesting increased muscle catabolism, as reflected by increased creatinine, alanine and citrulline levels. Supplementing with high levels of vitamin E/Se or vitamin D3/Ca or their combination did not appear to affect the metabolic remodeling triggered by HS.

Metabolite Profiling in the Liver, Plasma and Milk of Dairy Cows Exposed to Tansy Ragwort (Senecio jacobae) Pyrrolizidine Alkaloids

BACKGROUND

Plant-derived pyrrolizidine alkaloids (PAs) in feed cause metabolic disturbances in farm animals resulting in high economic losses worldwide. The molecular pathways affected by these PAs in cells and tissues are not yet fully understood. The objective of the study was to examine the dose-dependent effects of orally applied PAs derived from tansy ragwort in midlactation dairy cows.

METHODS

Twenty Holstein dairy cows were treated with target exposures of 0, 0.47, 0.95 and 1.91 mg of total PA/kg of body weight/d in control, PA1, PA2 and PA3, respectively, for 28 days. Liver tissue biopsy and plasma and milk samples were taken at day 28 of treatment to assess changes in metabolic pathways. A targeted metabolomics approach was performed to detect the metabolite profiles in all compartments.

RESULTS

The PA-affected metabolite profiling in liver tissue, plasma and milk revealed changes in three substrate classes: acylcarnitines (ACs), phosphatidylcholines (PCs) and sphingomyelins (SMs). In addition, in the plasma, amino acid concentrations were affected by PA exposure.

CONCLUSIONS

PA exposure disturbed liver metabolism at many sites, especially devastating pathways related to energy metabolism and to amino acid utilization, most likely based on mitochondrial oxidative stress. The effects on the milk metabolite profile may have consequences for milk quality.