Exercise- and metabolism-associated blood variables in Standardbreds fed either a low- or a high-fat diet

Incorporation of sunflower oil or linseed oil in equine compound feedstuff: 1 Effects on haematology and on fatty acids profiles in the red blood cells membranes

Eight trained horses (6 mares - 2 geldings, 6 Selle Français, 2 Trotteur Français, 12 ± 5.8 years old, 538 ± 72.5 kg) were offered three diets to potentially affect haematology and the fatty acids (FA) profiles in red blood cells (RBC) membranes. The control diet was composed of 50% hay and 50% concentrate containing mainly rolled barley (48%) and whole spelt (48%). In the case of sunflower oil diet, sunflower oil (62.0% of α-linoleic acid, LA) was incorporated at a rate of 8% and substituted by an equal proportion of barley. In the linseed oil diet, first cold-pressed linseed oil (56.0% of α-linolenic acid, ALA) was utilised at a similar incorporation rate of 8%. The experimental design consisted of three 3 × 3 latin squares with one being incomplete. Each period lasted 8 weeks. On average, the total feed intake (straw excluded) was 6.2 kg/day and the oil intake 0.278 kg/day. The oils significantly increased the concentrations of RBC, haemoglobin and haematocrit. The oils had no significant impact on the haematology profiles except that platelets tended to decrease in both oil-based diets. The most abundant FA in the RBC membranes of the control diet samples were in the decreasing order LA, C18:1n9-7, C18:0, C16:0 and the arachidonic acid (ARA) respectively. The sunflower oil supplementation slightly increased the amount of LA (36.23 vs. 34.72 mg/dl, p = 0.55) and C22:4n-6 (0.21 vs. 0.09 mg/dl, p = 0.22), while the decrease was observed in case of other FA (C16:1n-7, 1.08 vs. 1.42 mg/dl, p = 0.03), C20:3n-6 (0.22 vs. 0.31 mg/dl, p = 0.02), and ARA (1.17 vs. 1.63 mg/dl, p = 0.08). Linseed oil induced similar effects in the n-6 series FA profiles. In the context of practical applications, our results show that linseed oil incorporation in the diet could improve the haematology and the n-3 FA profiles potentially leading to an increased performance.

Aerobic exercise produces changes in plasma IL-6 but not IL-1b in four-beat gaited horses

Exercise is an important stressor and is correlated with cytokine production in several tissues. There is little information about changes in interleukin (IL)-6 and IL-1b in four-beat gaited horses during a typical aerobic exercise challenge. The objective of this research was to characterise changes in plasma IL-6, IL-1b, cortisol and other blood biomarkers in four-beat gaited horses after a marcha simulation test. We subjected 12 fit horses (approximately 5 years old and 390 kg) to the marcha simulation test (MST) (i.e. a 10 min warm-up, 30 min at marcha and 15 min cool down). Blood samples were collected before the MST, immediately after the MST and 15 and 120 min after the MST (i.e. recovery). Results were analysed with One Way Repeated Measures ANOVA and a Tukey tests with P≤0.05 and Pearson correlation test. The highest value of plasma IL-6 was observed immediately after MST (6.85 pg/ml) (P≥0.05). IL-1 and cortisol did not change (P≥0.05). However, creatine kinase (CK) and aspartate aminotransferase, nonesterified fatty acid (NEFA), glycerol, total cholesterol and glucose were elevated immediately after the MST and at 15 min after the MST (P≤0.05). No change was observed in alanine aminotransferase and triglycerides (P>0.05). Medium correlation was observed between NEFA and glycerol (R=0.64) and glycerol and triglycerides (R=0.50). In conclusion, an increase in IL-6 immediately that occurred after marcha simulation test was associated with elevated concentrations of several energetic metabolites (NEFA, glycerol and glucose). This metabolic adaption may contributed to the horses’ performance during their typical aerobic exercise and was not associated with significant elevation in IL-1b, CK, and cortisol in healthy trained four-beat gaited horses.

Hydration status of horses performing endurance exercise: II. Evidence for a role of dietary fibre type, not oil supplementation

The equine large intestine has been suggested to serve as a water reservoir during prolonged exercise and may be influenced by dietary fibre source or length. At the same time, oil supplementation may result in performance and possibly hydration advantages. This study was designed to examine the effect of different fibre-based feeds, of similar particle size, on hydration status, with and without oil supplementation. Six two-year-old Arabian horses were randomly assigned to diets containing either chopped grass hay (G) or a 50:50 chopped grass hay: fibre-based chopped mix (GC) and either oil supplementation (approximately 5.7% crude fat in total diet) or no oil supplementation. Horses consumed each diet at least 21 d before completing a 60 km exercise test. Total body water, determined using deuterium oxide (D2O), was 66.1% of body mass and did not differ due to treatment. Horses consuming GC had greater (P<0.05) body mass at the start of exercise than those consuming G. Water consumption during the exercise test was greater in G than GC (P<0.01; 13.3±1.3 l, 10.9±1.3 l), as were packed cell volume (P<0.01; G 36.8±1.2%, GC 35.1±1.2%) and plasma aldosterone across all times (P<0.001; GC 0.79±0.11 pmol/l, G 1.48±0.11 pmol/l). The results suggest dietary fibre source may play a greater role in hydration status over 60 km distances than does oil supplementation. Core temperatures reported in this study were all similar to those reported in a previous study using a 50:50 long hay to chopped highly digestible fibre mix and lower than reported in previous studies using long stemmed hay or pasture suggesting the particle size or length of the fibre may have an influence and thus merit further investigation.

Daily pattern of some fatty acids in the athletic horse

In the sport field, non-esterified fatty acids (NEFA) are important for the physical performance during the aerobic exercise of short intensity and long duration. In man, rat, goat and in the sedentary horse studies on the chronometabolism showed the presence of a circadian rhythm of the plasmatic concentration of NEFA while data for the athletic horse are lacking. To define a chronogram helpful for a specific planning and the differentiation of the training programmme in the athletic horse, the circadian pattern of some fatty acids (NEFA, palmitic, stearic, oleic, linoleic and linolenic acids) was studied in five Sella Italiana horses. These horses trained following a daily model of activity consisting of walk, trot, gallop and jump of obstacles of different heights. Blood samples were collected from the jugular vein every 4 h, starting at 08:00 hours, for 2 days to assess the concentrations of total NEFA (by spectrophotometry), palmitic, stearic, oleic, linoleic and linolenic acids (by gas chromatography). anova for repeated measures showed a statistical significant effect of the time of the day in NEFA, oleic and linolenic acids. The application of the periodic model showed the periodic pattern of NEFA, oleic, linoleic and linolenic acids. Acrophases were in the afternoon for all parameters. The results obtained showed a different trend of the circadian pattern of the studied parameters in the athletic horse than in the sedentary one because the physical activity and the post-prandial metabolism acted as zeitgebers.