Implementation of field cardio-respiratory measurements to assess energy expenditure in Arabian endurance horses

International audienceMeasurements of respiratory exchanges in genuine exercise conditions are undoubtedly of interest to further define the energy needs of endurance horses. However, the equine K4b2, the gas exchanges portable device validated for equines, has not been used in Arabian endurance horses yet. Therefore, the objective of this study was to implement field cardio-respiratory measurements in such horses using the equine K4b2 in order to assess energy expenditure (EE). Measurements of heart rate (HR), oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory frequency (RF), tidal volume (VT) and minute expired volume (VE) were carried out at rest and during a 20-min submaximal incremental field exercise in five trained Arabian endurance horses equipped with the K4b2 system. The relationship between HR and VO2 was determined for each horse. EE of the exercise session was calculated from direct VO2 measurements and individual HR-VO2 regression. Out of the five horses, four tolerated the equipment. Respiratory and metabolic variables at rest and during exercise, as well as EE measured at the different gaits, were consistent with reported values in exercising horses: VO2 ranged from 4.8 to 54.1 ml/min per kg from rest to canter, respectively, and EE from 82 to 1095 J/min per kg BW. The 20-min exercise session EE accounted for 6258 and 6332 J from direct VO2 measurements and individual HR-VO2 regression, respectively, which did not differ significantly. Providing an adaptation period and several technical adjustments, the present equine K4b2 could be used to assess EE in Arabian endurance horses in a controlled environment. The prediction of EE from the individual VO2-HR relationship might be an alternative method to evaluate EE when VO2 measurements are not possible

Effect of physical training on nutrient digestibility and faecal fermentative parameters in Standardbred horses

International audienceThis study aimed at evaluating, in previously inactive Standardbreds horses, the effect of 5 weeks of an exercise training programme on nutrient digestibility and faecal fermentative parameters (FFPs). As an increase in digestibility had previously been reported in trained endurance horses, we hypothesized that similar results would be found in horses being trained for other types of exercise on a different type of diet. After 3 weeks of dietary adaptation, a digestibility trial (DT1) was undertaken, over 3 days, in eight untrained Standardbreds with a fresh faecal sample being collected on the second day for FFP determinations. Six of the eight horses undertook a training programme, and after 5 weeks of exercise, the DT and the FFP measurements were then repeated (DT2). DT2 began after 3 days of inactivity. The same natural meadow hay (H) and pelleted complementary feed (CF) were fed throughout. For 5 days before the DTs, horses were fed 2.1% BW on a dry matter basis (55:45 ratio H:CF). Body weight and body condition score remained constant. Apparent digestibility of dry matter, organic matter, neutral detergent fibre, hemicellulose, crude protein and gross energy, as well as faecal total volatile fatty acids (VFA), acetate and propionate concentrations were significantly (p < 0.05) higher at DT2 than at DT1. A 5-week exercise programme had a positive impact on nutrient digestibility and FFP. Training may improve dietary energy supply, in particular via increased hindgut VFA production. The potential improvement of digestive efficiency with training should be taken into account when formulating nutritional recommendations for the exercising horse, particularly when performing light work, which is low-intensity exercise for 1-3 h per week

Effect of a moderate dietary fat supplementation on the digestive function in the horse

Supplementing athletic horses with fat to meet their high energy requirements may have a detrimental impact on the digestibility of fibre when fat was supplemented at the expense of an iso-energetic amount of non-structural carbohydrates (Jansen et al., 2000, 2002, 2007). The objective of this study was to determine the effect of a moderate fat supplementation on the total tract apparent digestibility and the colonic bacterial ecosystem. Six fistulated horses (449 +/- 33 kg) used in a double (3x3) Latin square experiment received a diet consisting of a forage-to-concentrate ratio of 67:33 on DM basis. Three fat concentrations were tested in the concentrate: 4.0, 7.0 and 8.8 % DM, respectively. Mean daily DM intake was 1.7% BW divided in two equal meals of hay and concentrate. The apparent digestibility (DM, TDF, NDF, ADF, Fat) was measured by total collection of faeces during 5 days. The anaerobic flora (total, cellulolytic, amylololytic, lacticolytic) and VFA concentrations and pH were determined in the colonic content collected 4 hours after the morning meal. The total fat intake 42, 59 and 69 g/100 kg BW for the rations composed of 4.0, 7.0 and 8.8% of fat in the concentrate. The digestibilities of DM, fat, TDF, NDF and ADF were not altered by the fat supplementation. In agreement with Jansen et al. (2007), the pH, total and cellulolytic bacterial concentrations in the content of the hindgut were not modified. Consequently, a moderate fat supplementation increased the energetic supply without any adverse effects on the hindgut ecosystem.vo