What are blood glucose and beta-hydroxybutyrate (BHBA), and why is it important to monitor their levels in young calves?

Blood glucose is a primary sugar that the body uses for energy, while beta-hydroxybutyrate (BHBA) is a ketone body produced when the body breaks down fat for energy. By monitoring these metabolites in the blood, it is possible to gain insights into a calf's energy balance and overall health. For example, during weaning the levels of both BHBA and glucose increase with increasing starter intake. This is important because imbalanced levels of these can signify health and nutritional problems.

How does starter intake affect blood glucose and beta-hydroxybutyrate (BHBA) levels in young calves?

Starter intake greatly influences both blood glucose and beta-hydroxybutyrate (BHBA) levels. As starter intake increases, blood BHBA levels tend to rise, while glucose levels decrease. This indicates that calves are shifting towards using fat for energy as they consume more solid feed. Notably, there's an interplay with the age of the calf, younger calves demonstrate higher glucose levels, indicating a difference in metabolism as they develop.

How does stress, like that from vaccinations, influence blood glucose and beta-hydroxybutyrate (BHBA) levels in young calves?

Stress, especially induced by vaccination, can significantly impact blood beta-hydroxybutyrate (BHBA) levels, causing them to decrease. However, blood glucose levels appear to be unaffected by vaccination stress. It's essential to manage stress factors, as stable BHBA levels are indicative of consistent metabolic profiles.

How does the age of a calf affect its blood glucose levels?

Age influences blood glucose levels in young calves, with calves in the first 5 weeks of life exhibiting higher blood glucose concentrations compared to older calves. This suggests that as calves mature, their glucose metabolism changes, which reflects the development of the calf's digestive system. It is worth noting that the stage of the calf development determines how they process and utilize energy sources.

What happens to blood glucose and beta-hydroxybutyrate (BHBA) levels when a calf's starter intake is restricted?

Restricting starter intake can affect both blood beta-hydroxybutyrate (BHBA) and blood glucose concentrations in young calves. Research has demonstrated that after intake restriction, BHBA levels decrease for about 3 days, while glucose levels decrease for about 2 days. This shows how important consistent feed intake is for maintaining stable metabolic profiles in calves, so they get the nutrition they require.

Digital illustration of a calf in a lab setting, surrounded by glucose and BHBA molecules, symbolizing metabolic health.

Decoding Calf Health: How Blood Markers and Starter Intake Impact Growth

Reese Marlowe in Science & Nature September 2025 • 5 min read.

"Unlocking the secrets of calf metabolism: A deep dive into how blood glucose and BHBA levels, influenced by starter feed, shape early development."

Raising healthy calves is crucial for successful dairy operations, and understanding their nutritional needs during the early stages of life is key. Researchers have been investigating how various factors, such as age, diet, and stress, influence the metabolic health of young calves. A recent study focused on the interplay between blood glucose and beta-hydroxybutyrate (BHBA) levels, and how these are impacted by starter intake, age, stress, and weaning processes.

Beta-hydroxybutyrate (BHBA) is a ketone body produced when the body breaks down fat for energy. Glucose, on the other hand, is a primary sugar used for energy. Monitoring these two metabolites in the blood can provide insights into a calf's energy balance and overall health. The study aimed to determine if either blood BHBA or glucose could serve as a reliable indicator of starter intake in young calves.

The study design involved monitoring Holstein calves from 1 to 9 weeks of age, tracking their blood BHBA and glucose concentrations under different conditions. These conditions included varying starter intakes, age-related changes, vaccination-induced stress, and intake restrictions. Blood samples were collected at specific times, and metabolite levels were measured using test strips.

Understanding the Factors Influencing Blood BHBA and Glucose Levels in Calves

Digital illustration of a calf in a lab setting, surrounded by glucose and BHBA molecules, symbolizing metabolic health.

The research explored several factors that could potentially impact blood BHBA and glucose levels in young calves. These factors included the calf's age, the time of day, the amount of starter feed consumed, stress levels (specifically vaccination stress), and any restrictions in feed intake. The goal was to understand how these elements independently and collectively affect the metabolic markers.

Age played a significant role in blood glucose levels. Calves in the first 5 weeks of life had higher blood glucose concentrations compared to those in weeks 6 and 7. This suggests that as calves mature and their digestive systems develop, their glucose metabolism changes. The study also found that blood BHBA levels increased with increasing starter intake, while glucose levels decreased. This indicates that as calves consume more solid feed, their bodies shift towards using fat for energy, leading to higher BHBA and lower glucose levels.

Starter Intake: Increasing starter intake led to higher blood BHBA and lower glucose levels.
Age: Younger calves (first 5 weeks) had higher blood glucose compared to older calves.
Vaccination Stress: Blood BHBA decreased due to vaccination, but glucose was unaffected.
Intake Restriction: Reduced BHBA for 3 days and glucose for 2 days after intake restriction.
Weaning: Around weaning, both BHBA and glucose increased with increasing starter intake.

Stress, induced by vaccination, had a notable impact on blood BHBA levels, causing them to decline. However, glucose levels remained unaffected by vaccination stress. Restricting starter intake also influenced both BHBA and glucose concentrations, with BHBA levels decreasing for 3 days and glucose levels decreasing for 2 days following the restriction. These findings suggest that maintaining consistent feed intake and minimizing stress are crucial for stable metabolic profiles in calves.

Implications for Calf Management

The study's findings highlight the complex interplay between various factors affecting blood BHBA and glucose levels in young calves. While neither blood BHBA nor glucose proved to be a straightforward proxy for estimating starter intake, monitoring these metabolites can still provide valuable insights into a calf's metabolic health and nutritional status. Dairy farmers and calf managers can use this information to optimize feeding strategies, minimize stress, and ensure healthy growth trajectories in young calves. Further research is needed to explore additional biomarkers and refine our understanding of calf metabolism, ultimately leading to more effective management practices.