Comparison of bone mineral content and biochemical markers of bone metabolism in stall- vs. pasture-reared horses.

This research study examines the impact of different methods of rearing (stall vs. pasture) on yearling Arabian horses’ bone health, indicated by their bone mineral content and key biochemical markers in their blood and urine. The findings suggest that horses confined to stalls may have lower bone mineral content when compared with those reared on pastures.

Study Design and Methodology

• The researchers designed a controlled experiment involving sixteen yearling Arabian horses that were randomly divided into two groups: one confined in stalls and the other allowed to live on a pasture.
• The experiment lasted 140 days, including an initial pretraining period of 84 days, after which six horses from each group were randomly picked to undergo a 56 day training period.
• To track changes, blood samples were collected every 14 days for determination of serum osteocalcin concentrations which is a marker of bone formation, and urine samples were collected every 24 hours in order to assess urinary deoxypyridinoline concentrations.
• The deoxypyridinoline in their urine is a biomarker indicating bone resorption or the breakdown of bone tissue.
• Radiographs of the left forelimb were taken every 28 days to assess changes in the bone mineral content of the third metacarpus, using a technique called Radiographic Bone Aluminum Equivalency (RBAE).

Key Findings

• At the outset and throughout most of the experiment, the horses confined to stalls showed lower RBAE values both laterally and medially, indicating less bone mineral content compared to their pastured counterparts.
• Consequently, the onset of training did not offset this decrease in bone mineral content in the stall-confined horses.
• Biochemical markers also displayed differences between the two groups. More specifically, serum osteocalcin concentrations, indicating bone formation, were lower in the confined horses, and urinary deoxypyridinoline concentrations, indicating bone resorption, were higher in them, implying more bone loss.

Implications of the Study

• The findings indicated that confinement in stalls might lead to a loss of bone mineral content in young horses when compared to those reared in pastures.
• This provides useful insights for horse-breeders, trainers, and owners concerning optimal rearing conditions to support the bone health of the horses during their development phase.
• However, these findings may need to be examined further under different conditions, and in different horse breeds, to establish more concrete conclusions.