[Course of blood levels of calcium, inorganic phosphate, alkaline phosphatase, parathyroid hormone and calcidiol (25-OH-D3) in one and two year old thoroughbred horses].

The research focused on determining levels of select minerals and hormones in the blood of one to two year old thoroughbred horses, and how these levels change depending on the seasons and age. The primary substances measured were calcium, inorganic phosphate, parathormon, 25-OH-D3, and the activity of alkaline phosphatase.

Methodology

• Data was taken monthly over a year from a group of 44 one-year-old thoroughbred horses.
• These horses came from four different studs and the measurements were recorded during both grazing seasons, typically warmer months, and stable or training seasons, which are usually colder periods.
• The concentration of calcium, inorganic phosphate, and the activity of alkaline phosphatase were established using a photometric method – a technique that determines the compositions of solutions based on their color intensities.
• The levels of parathormon and 25-OH-D3, on the other hand, were measured with a radioimmunoassay, which is a technique that uses antibodies to bind with specific materials in order to determine their concentration.

Findings

• The calcium levels of one-year-old thoroughbred horses during the grazing season were found to be 3.03 +/- 0.23 mmol/l which was slightly lower than the stable season with levels of 3.14 +/- 0.14 mmol/l.
• The concentration of inorganic phosphate varied significantly with age and season, with 1.7 +/- 0.19 mmol/l during grazing season and 1.3 +/- 0.19 mmol/l during the stable season.
• Akin to phosphate, alkaline phosphatase’s activity was also affected notably by age, observed as 403 +/- 86 U/l during grazing season and decreased to 308 +/- 65 U/l during winter.
• Parathormon average levels were much higher during grazing than stable season, recorded as 1.27 +/- 0.45 ng/ml and 0.9 +/- 39 ng/ml respectively. However, individual horses showed large differences in their parathormon levels.
• Interestingly, 25-OH-D3 concentrations were lower during grazing season (10.38 +/- 3.08 ng/ml) as compared to the winter period (13.03 +/- 2.86 ng/ml).

The researchers provided these results on horse’s nutritional state in relation to season and age, correlating them with relevant literature to further analyze their implications.