Chromium or l-carnitine supplementation during an aerobic conditioning program mildly modified the energy metabolism biomarker response in Mangalarga Marchador fillies

Chromium (Cr) and L-carnitine (LC) are potentially ergogenic substances for athletic horses since they are suggested to increase energy availability for the exercise and postpone the onset of fatigue. The present study aimed to assess the effect of supplementation with chelated chromium or L-carnitine on markers of energy metabolism in Mangalarga Marchador (MM) fillies subjected to marcha treadmill tests. Thirteen fillies were randomly assigned to three groups: Cr (n¼4; 10 mg/day chelated chromium), LC (n¼4; 10 g/day L-carnitine), and Control (n¼5; no supplementation). The research followed a completely randomized split-split-plot design. Each marcha test represented a plot, each nutritional supplementation group represented a split plot, and each moment in marcha tests represented a split-split-plot. The animals were exercised on the treadmill and automated walker on alternate days from Tuesday to Sunday for 42 days. Treadmill marcha tests took place on days 7 (Test 1), 21 (Test 2), and 42 (Test 3) with 5 min of warmup (1.7 m s � 1 ) followed for 30 min of marcha (3.5 m s � 1 and 3% slope). Heart rate (HR), blood lactate (Lac), blood glucose (Glu), and serum triglyceride levels (Trigl) were assessed before exercise and every 5 min during the marcha tests. The data underwent repeated measures analysis of variance and the means were compared by Tukey's test (Pr0.05). The Cr group had lower HR (Po0.05) at 20 min in Test 1; higher Lac (Po0.05) in Test 1 (from 10 to 35 min), Test 2 (at 10, 30, and 35 min), and Test 3 (at 10 min); and higher Glu (Po0.05) in Test 1 (from 20 to 35 min) and Test 2 (at 15 and 25 min). The LC group had higher (Po0.05) Glu in Test 1 (0 min) and lower Trigl (Po0.05) in Test 2 (at 25 and 30 min). As early as 21 days into conditioning (Test 2), a reduction (Po0.05) was found on HR, Lac, and Glu, however, Trigl was not affected by the conditioning (P40.05). The treadmill marcha tests showed a mild effect of chromium or L-carnitine supplementation on the energy metabolism markers of MM fillies subjected to an aerobic conditioning program. LC or Cr supplementation associated with an aerobic conditioning program did Contents lists available at ScienceDirect