Adiposity and leptin concentrations in Thoroughbred mares

Abstract

Circulating leptin is related to adiposity. This study characterized the relationships between changes in adiposity and leptin concentrations in mares before and after an increase in body condition. Plasma leptin concentrations and indicators of adiposity were measured in 20 Thoroughbred mares before and after moderate weight gain (BW, 572 ± 47 kg vs. 598 ± 50 kg; body condition score (BCS), 6.0 ± 0.8 vs. 6.5 ± 1.0 on a scale of 1 to 9; leptin 3.0 ± 1.8 ng/ml vs. 4.0 ± 2.9 ng/ml; P < 0.05). Fat mass accumulated more in the rump vs. rib, back or shoulder (P < 0.05). Changes in leptin concentrations were associated with changes in BCS (r = 0.50, P < 0.020). From linear regression analysis, a one unit change in BCS corresponded with a 0.5 ± 0.1 cm alteration in rump fat thickness (r2 = 0.55, P < 0.001). An increase in rump fat thickness of 1.0 ± 0.05 cm was associated with a 2.0 ± 0.5 ng/ml increase in leptin concentration (r2 = 0.41, P < 0.003). Therefore, a moderate increase in adiposity in Thoroughbred mares, measured by BCS and rump fat thickness, resulted in an increase in circulating leptin concentrations. Research supported by the late Paul Mellon and the WALTHAM Centre for Pet Nutrition.