Stress, Metabolic and Serum Muscle-Derived Enzymes Response of Horses Employed in Wooded Area and Field Trekking Courses.

Horse trekking is a non-competitive sport that, as other kinds of exercise, involves skeletal muscle effort and may implicate significant energy expenditure leading to stress. The aim of the current study was to assess the effect of trekking on metabolic and stress response as well as muscle damage markers in clinically healthy horses. Thirty horses were equally divided in 3 groups according to trekking course: Group A (trekking course 15 km long), Group B (trekking course 35 km long starting;), Group C (three trekking courses for three consecutive days; during the first day the trekking course was 25 km long, Group C1; during the second day the trekking course was 40 km long, Group C2; during the third day the trekking course was 25 km long, Group C3). Blood samples were collected from each horse before trekking (TPRE), after 5 min (TPOST) and 1 h from the trekking end to assess lactate, glucose, total proteins, non-esterified fatty acids (NEFAs), creatinine, aspartate aminotransferase (AST), creatine phosphokinase (CPK), lactate dehydrogenase (LDH) and cortisol concentration. Higher cortisol, lactate, glucose, NEFAs, creatinine, CPK, LDH and AST values were found after trekking than rest (P < .001). Horses of Groups C2 and C3 showed higher values of the investigated haematochemical parameters and muscle enzymes than Groups A and B. The findings suggest that trekking induces a metabolic reaction accompanied by an acute stress response in horses and underline that this recreational exercise, if not associated with the adequate recovery period, can increase the probability of muscle damage.

Dynamic Metabolic Response, Clotting Times and Peripheral Indices of Central Fatigue in Horse Competing in a 44 Km Endurance Race.

A deep knowledge on metabolic response of athlete horse to exercise is of paramount importance for the development of optimal training programs to attain equilibrium between good performance and animal welfare. This study investigated the dynamic change of metabolic, clotting times and peripheral indices of central fatigue in horses competing in an official 44 km endurance race.  From 6 horses blood samples were collected at rest (TPRE), within 5 minutes from the end of race (TPE5), after 30, 60 minutes after the end of race (TPE30 and TPE60) to investigate the values of blood lactate, glucose, platelets (PLTs), serum leucine, isoleucine, valine, tryptophan, the ratio between tryptophan and branched-chain amino acids (BCAAs) levels (Try/BCAAs), total proteins, non-esterified fatty acids, plasma thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time and fibrinogen (Fb). Lactate, PLTs, non-esterified fatty acids, BCAAs and Try/BCAAs showed higher values at TPE5, TPE30and TPE60than TPRE(P < .0001); glucose showed lower values at TPE5, TPE30and TPE60than TPRE(P < .0001). Higher TT values were found at TPE5, TPE30and TPE60than TPRE, and at TPE5than TPE30 and TPE60(P < .0001); Fb was higher at TPE5than TPRE, T PE30and TPE60(P < .0001). This survey confirms that horses performing prolonged physical exercise experienced glycolysis, lipid mobilization and amino acid metabolism to provide substrates as fuel for muscle contraction.

Uncoupling Protein-1 (UCP1) in the Adult Horse: Correlations with Body Weight, Rectal Temperature and Lipid Profile.

This study aimed to evaluate the possible relationship among UCP1, body weight, rectal temperature and lipid profile in the horse. Thirty clinically healthy Italian Saddle geldings (6-10 years old) were enrolled after the informed owners' consent. All horses were blood sampled and their body weight and rectal temperatures were recorded. On the sera obtained after blood centrifugation the concentration of UCP1, total lipids, phospholipids, non-esterified fatty acids (NEFAs), triglycerides, total cholesterol, high density lipoproteins (HDLs), low density lipoproteins (LDLs) and very low density lipoprotein fraction (VLDLs) was evaluated. Pearson's correlation analysis was applied to assess the possible relationship between serum UCP1 concentration and the values of body weight, rectal temperature and lipid parameters. Serum UCP1 concentration showed no correlation with body weight, rectal temperature, HDLs and LDLs values, whereas it correlated negatively with serum total lipids, phospholipids, NEFAs, total cholesterol, triglycerides and VLDLs values (p < 0.0001). The findings suggest that in the adult horse the role of UCP1 is linked to the lipid metabolism rather than to thermoregulation.