The transition period refers to the time from approximately three weeks before calving to three weeks after. It represents one of the most critical stages in the lactation cycle of a dairy cow, as it lays the foundation for future milk production.
Cows that navigate this phase successfully tend to show higher milk yields, improved fertility, and longer productive lifespans.
During this time, cows undergo significant hormonal, physiological, and metabolic changes as they move from the dry period into early lactation.
These changes can have a profound impact on both animal health and milk production.
As dry matter intake typically decreases during the dry period, while the energy demands of the growing foetus and the onset of lactation increase, cows enter a state of negative energy balance.
To minimise the duration of this state, it is essential to formulate a well-balanced and palatable dry cow ration. Ensuring optimal feed intake requires consistent feeding management and ample access to fresh drinking water — preferably from trough drinkers rather than small automatic drinkers.
The prerequisite for an adequate mineral supply to prevent milk fever (usually caused by hypo-calcaemia) is a good feed intake as well as a ration balanced according to the Dietary Cation-Anion Balance (DCAB). In addition, calcium and phosphorus supplementation should be planned for animals at risk or during high-risk periods.
Furthermore, hormonal changes and the stress of calving put a strain on the cow’s immune system, increasing the risk of infectious diseases in freshly lactating cows.
With the help of optimised rations, consistent feed intake, and systematic health management with targeted checks, we can guide cows well through the transition period.
How can clinical laboratory diagnostics help us with this?
Clinical laboratory tests should specifically answer the following questions:
- Are the animals consuming enough feed, and does the ration meet their energy requirements?
- Is the mineral supply adequate with regard to clinical and subclinical milk fever?
- What is the immune status of the animals?
Parameters that provide information about feed intake, the metabolic situation, and the immune status of the animals are shown in the following table (Table 1):
Table 1: Overview of relevant metabolic parameters during the transition period
| Parameter | Meening |
| Protein | Protein supply ↑ prolonged inflammatory process ↓ protein loss (individual animal diseases) |
| Albumin | ↑ dehydration ↓ acute immune response (negative acute-phase protein) ↓ reduced feed intake ↓ severe liver damage |
| Globulin | ↑ increased immunoglobulin production |
| Urea | ↑ protein oversupply, possibly with simultaneous energy deficiency ↓ protein deficiency in the ration ↓ reduced feed intake |
| Cholesterol | ↓ reduced feed intake |
| Bilirubin | ↑ reduced feed intake (starvation jaundice) ↑ liver burden |
| GLDH | ↑ liver burden, destruction of liver tissue |
| γ-GT | ↑ liver burden, fatty liver |
| NEFA | ↑ fat mobilisation due to reduced feed intake / energy deficiency in the ration |
| β-HBS | ↑ ketotic metabolic state due to poor feed intake / energy deficiency in the ration |
The determination of minerals in blood and urine – particularly calcium, but also phosphate and magnesium – is essential for diagnosing both clinical (e.g. recumbency) and subclinical forms of milk fever (e.g. labour weakness, retained placenta, abomasal displacements). Other macrominerals such as potassium, sodium and chloride are also useful for assessing nutrient supply and for ration formulation, including the calculation of the dietary cation-anion balance (DCAB).
To assess the immune status of a cow, clinical chemistry parameters such as total protein, albumin, globulins, a blood count, and acute-phase proteins are useful. In the case of inflammation, increases in total protein and globulins only become apparent after a few days. The same applies to blood count changes, such as a rise in total leukocyte numbers or shifts in leukocyte sub-populations, particularly neutrophilia.
Acute-phase proteins are more sensitive and specific markers of inflammation.
Albumin is considered a negative acute-phase protein, as the liver shifts its synthesis towards transporters, mediators, modulators, and inhibitors during the acute-phase response, leading to reduced albumin levels.
The main acute-phase proteins in cattle are haptoglobin and serum amyloid A (SAA).
An increase in these proteins in the blood is an early indicator of inflammation and is also suitable for detecting subclinical inflammatory processes.
SAA tends to rise more rapidly, whereas haptoglobin remains elevated for a longer period.
A screening focusing on the described examination points can be supplemented, as needed, with additional questions and specific farm requirements, such as evaluation of milk yield data, feed analyses, measurement of backfat thickness, trace element testing, and diagnostics of acidotic or alkalotic conditions through NSBA measurement in urine.
A few words about pre-analytics:
Pre-analytical conditions are often suboptimal in field practice. So how can they be improved?
Plan herd visits in a way that allows you to collect samples from multiple animals and ensures they can be processed at the practice as soon as possible afterwards.
During transport, store blood samples upright – keep them cool in summer and protect them from frost in winter.
Serum is suitable for most clinical chemistry tests, while EDTA blood is required to prepare a blood count. To obtain serum, collect the blood directly into a serum tube and allow it to clot at room temperature for 20–30 minutes. It should then be centrifuged as soon as possible, and the supernatant pipetted off and transferred into a neutral tube. The separated serum can be stored cooled or frozen.
EDTA blood should be collected directly into an EDTA tube, ideally after the serum sample.
The first jets of blood contain more clotting factors, which increase the risk of clotting in the EDTA sample. Swirl the EDTA tube gently several times to mix. EDTA blood may be cooled, but must never be frozen. Avoid any contamination of the serum with EDTA (e.g. by mixing up the tube lids), as this can significantly alter the electrolyte values.
Good pre-analytical practice helps prevent haemolysis, which can particularly distort mineral analysis results.
Conclusion
Effective monitoring during the transition period plays a vital role in maintaining animal health and positively impacts milk yield.
Dr. Anna-Linda Golob, Swanhild Wagenfeld
Our services relating to the transition period:
- Transition profile (including blood count)
- Transition profile + haptoglobin (including blood count)
- Transition profile + NSBA (including blood count)
- Serum amyloid A testing
