The purpose of this study is to examine the effects of various rest periods during intermittent exercise with respect to blood lactate concentrations in Thoroughbred horses. Four Thoroughbred horses each underwent three types of intermittent exercise program and blood lactate concentrations during the exercise, which was carried out on a 7% inclined treadmill, were measured. The intensity of each bout was set at 116% HRmax for 50 sec. Each program comprised three bouts separated by rest periods set at either 2, 5 or 15 min. Blood lactate concentrations during the second and third bouts increased approximately 6 mmol/l in the 15-min intermittent exercise program, but almost no changes were observed during all bouts in the 5-min intermittent exercise program. By contrast, blood lactate concentrations decreased during bouts in the 2-min intermittent exercise program. It is considered that this suggests more lactate in muscles was oxidized to supply energy in the 2-min intermittent exercise program than in the other two exercise programs. It is therefore suggested that a 2-min intermittent exercise program more effectively stimulates the lactate oxidation system in Thoroughbred horses than do programs with longer rest periods.
This study investigated the lying behavior of horses in the stable with used bedding material (rice straw) that was dried in sunshine. Six geldings were used in this study. Three types of straw were prepared: fresh straw that was not used as bedding materials before (New), used straw that was dried in sunshine for eight hours (UD), and used straw that was kept in a shaded area (U). Horses' behavior was observed during the night (16:30-5:30). Although there were no significant differences in the total duration of the recumbent position on three types of straw, four and three geldings lay more than 60 min in the stable on New and UD straw, respectively, whereas no geldings lay more than 47 min on U straw. Furthermore, short lying bouts (less than ten minutes) were seen three times in the stable with U straw whereas such were never seen in the stable with New and UD straw. The water content of U straw was significantly higher than in New and UD, and there was no difference between New and UD. The airborne ammonia (ANH3) concentration in the stable with U straw was significantly higher than that in New straw, but there was no significant difference between UD and U straw. In conclusion, horse's lying behavior was disturbed in the stable with used straw, but drying the used straw in sunshine can relieve this disturbance. Nevertheless, drying in sunshine was not enough to remove the urine ammonia completely from used straw, and this might be one of the causes of incomplete relief of the disturbance.
Virulent Rhodococcus equi is an important pathogen in foals aged 1 to 3 months, but its incidence in Tennessee, U. S. A., is poorly understood. Ten soil samples were collected from a Tennessee walking horse farm in Tennessee. The presence of R. equi was investigated and 107 isolates were tested for the presence of 15- to 17-kDa antigens (VapA) by immunoblotting and PCR. R. equi was isolated (103-104 colony forming units/g) from 8 of the 10 soil samples. Twenty-four VapA-positive isolates were detected from 7 of the 8 culture-positive samples with a prevalences ranging from 6.7 to 50%. Of the 24 virulent isolates, 21 contained an 85-kb type I plasmid, and 3 contained an 85-kb type III plasmid which had been uniquely isolated from soil isolates in Texas. There was no evidence of R. equi infection on the farm, but the virulent form was widespread in the soil environment of the farm.
The effects of mosapride, a 5-hydroxytryptamine 4 (5-HT4) receptor agonist, on the motility of horse small intestine were examined by means of electrointestinography (EIG). Six adult healthy thoroughbreds were used, in which EIG signals from the small intestine were measured by a Degetorappar EGG system. Mosapride, dissolved in 200 ml water, was orally administered at a dose of 2 mg/kg. The total power of EIG signals at a frequency band of 3 cpm was 419.1 ± 122.0 (μV) 2 × cpm (n=6) before, and 2,093.6 ± 850.0 (μV)2 × cpm (n=6) after the drug administration, the latter mean value being significantly greater than the former. This result suggests that mosapride has a prokinetic action on the motility of horse small intestine.