In this study, serum vitB
12 and phosphorus concentrations were investigated in hyperketonemic postpartum dairy cows. Our results indicated that hyperketonemic cows had similar serum vitB
12 and phosphorus concentrations compared to healthy cows.
The diagnosis of ketosis is mostly based on the measurement of blood BHBA concentrations, as this parameter has substantial correlations with vitamin and mineral metabolism. The observed sixfold rise in BHBA is in aggreement with other studies of metabolic abnormalities associated with clinical ketosis11,12. BHBA values of ≥1,400 μmol/L within the first two weeks postpartum are strongly indicative of clinical ketosis onset. Our analysis revealed that the average BHBA level in the hyperketonemic group was 5.30 mmol/L (5.300 μmol/L), indicating a severe state of ketosis. This result corresponds with the established threshold values and the findings that BHBA levels over 0.54 mmol/L on postpartum day 10 signify hyperketonemia13,14.
The significant increase in BHBA concentration may be due to variations in vitamin B12 levels. A recent study suggests that the metabolic state may have an impact on the bioavailability of vitamins generated by rumen bacteria15. Even if this trend did not reach statistical significance, it is crucial to take into account the potential biological significance of the reported rise in vitamin B12 levels in hyperketonemic cows. Previous research on the relationship between vitamin B12 and hyperketonemia has produced contradictory findings. Duplessis et al., 16 found no association between plasma or milk vitamin B12 concentrations and hyperketonemia (defined as BHBA ≥1.2 mmol/L), while Korpela and Mykkänen17 found that the serum vitamin B12 levels of ketotic cows were significantly lower than those of healthy cows (268 ± 64 pg/mL vs. 362±154 pg/mL; p<0.02). Similarly, Corse and Elliot18 found that the vitamin B12 levels were lower in cows with spontaneous ketosis in late pregnancy. However, Obitz and Fürll19 found that the postpartum vitamin B12 levels of the affected mice dropped less precipitously. These contradictory results suggest that vitamin B12 dynamics in ketotic states are complex and may be influenced by several factors, including the level of metabolic imbalance and the lactation stage. Therefore, even in the lack of statistical significance, the increasing trend in our study might suggest an early shift in vitamin B12 metabolism in response to metabolic stress or a compensatory physiological response. This finding is supported by a prior study demonstrating that increased plasma free fatty acid (FFA) levels in cows were associated with elevated vitamin B12 concentrations in both milk and plasma3. This study indicates that lipolysis, occurring during negative energy balance, may indirectly influence B12 metabolism by altering the rumen microbiota or the kinetics of vitamin absorption. However, as serum FFA concentrations were not evaluated in our study, it is hard to determine whether the observed increase in vitamin B12 levels may be ascribed to such causes. Thus, our interpretation relies solely on previously published data, lacking corroborative metabolic evidence from our own research. The absence of FFA data is a considerable constraint of the present investigation, and we advocate for future research to include the evaluation of serum FFA levels to clarify this possible biological connection. Similar to our results increased serum vitB12 concentrations were reported in hyperketonemic goats and cattle with tropical theileriosis20-22.
Blood BHBA levels primarily dictate the diagnosis of ketosis, since this test exhibits substantial relationships with mineral and vitamin metabolism. Current reports indicate that butafosfan and cyanocobalamin (B12) injections may reduce BHBA levels and lower the occurrence of subclinical ketosis, particularly in cows with three or more lactations23. As no supporting medication was administered in our investigation, it is believed that the elevation in vitamin B12 levels may only pertain to metabolic reaction.
The evaluation of phosphorus should be considered in relation to the increase in BHBA. Despite elevated BHBA levels, no statistically significant difference in phosphorus concentrations was seen between the groups (control: 6.01 mg/dL; hyperketonemic: 5.46 mg/dL). The lack of significance may be partly due to individual variability; nonetheless, the observed decline in the hyperketonemic group, despite its statistical insignificance, may still hold biological relevance. Djoković et al.,24 suggest that ketosis may affect mineral metabolism, potentially altering phosphorus absorption and mobilization. Our findings correspond with those of Zhang et al.,25, which demonstrated that phosphorus homeostasis typically remains constant during the early stages of ketosis. This suggests that compensatory mechanisms such as adequate dietary phosphorus consumption or physiological regulation may help maintain serum phosphorus levels within normal limits, especially during the early stages of metabolic stress. Therefore, while the fluctuations in phosphorus levels lacked statistical significance, the observed pattern may suggest subtle metabolic adaptations that require more investigation.
As a conclusion, the results of this study showed that hyperketonemia induce negligible changes in serum vitB12 concentrations and it has limited interaction with serum phosphorus status.
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