Ultrasonographic measures of body fatness and their relationship with plasma levels and adipose tissue expression of four adipokines in Welsh pony mares.

The research investigates a novel method of evaluating body fat in horses using ultrasonography and further attempts to correlate these measurements with changes in metabolic markers and proteins called adipokines in the body. This has potential applications to assess the impact of an animal’s environment or lifestyle on its metabolic health and understand obesity-related disorders.

About the Study

• The study was conducted on 20 Welsh mares over a period from April to October.
• Mares were originally kept in a controlled, indoor environment, before being moved outdoors to graze in grasslands.
• A series of measurements were taken on a monthly basis including Body Weight (BW), Body Length (BL), Height at Withers (HW), Thoracic Perimeter (TP), a 5-point Body Condition Score (BCS), and Subcutaneous Fat Thickness (SFT).
• Subcutaneous Fat Thickness was measured at three points – the shoulder, lumbar region, and the rump, using ultrasonography – a non-invasive imaging technique.
• Further, plasma and adipose tissue samples were analyzed to assess the levels of certain metabolic indicators as well as several adipokines, proteins produced by fat cells that have endocrine functions.

Findings

• While there was no significant increase in the BW (P=0.0940), significant increases were observed in the TP (P=0.0002) and BCS (P<0.0001) over the study period. The SFT at the shoulder, lumbar region, and rump also increased significantly.
• Plasma concentrations of non-esterified fatty acids, phospholipids, and cholesterol increased significantly. However, triglycerides decreased significantly.
• Regarding the adipokines measured, a significant increase was observed in plasma concentrations and adipose tissue expression of leptin and resistin, while adiponectin levels significantly decreased. Visfatin levels remained unaffected.
• The opposite trend was observed in the expression of adipokine receptors as compared to their ligands.

Conclusions

• The study establishes ultrasonographic measurements of SFT at the shoulder, lumbar region, and rump as accurate indicators of fatness in mares.
• These ultrasonographic measurements showed correlation with adipokine plasma concentrations and expression of adipokine-related receptors in adipose tissue.
• The altered adipokine and metabolic profiles highlight the effect of the outdoor lifestyle and change in diet on mare metabolism and adiposity, thereby providing insights into potential physiological responses to the natural environment.
• The findings suggest potential implications for equestrian sports, as well as the broader field of understanding obesity-driven metabolic changes in mammals.