We investigated the effect of long slow distance training on aerobic work capacity in eleven 2-year-old Thoroughbred horses. Eight weeks of training (5 days/week) was performed on a track at a slow canter, 6 horses were cantered 3, 200 m for 3 weeks, and then increased to 4, 800 m for 5 weeks (Group L), while the other 5 horses were cantered 800 m throughout the same training period (Group S). Each horse performed an incremental exercise test on a treadmill before (Pre-test) and after (Post-test) the training period. In the Pre-test, there were no significant difference between Group L and Group S regarding Vo2Peak (152.6 ± 13.2 ml/kg/min in Group L vs 149.9 ± 17.1 ml/kg/min in Group S) or the slope of the regression line for Vo2 and running speed. Peak heart rates (HRpeak; 221.8 ± 6. 7 beats/min in Group L vs 225.6 ± 7. 7 beats/min in Group S), and peak blood lactate concentrations (LA peak; 1 4.4 ± 3.3 mmol/l in Group L vs 13.0 ± 3.5 mmol/l in Group S) were not significantly different between the two groups. In the Post-test, there were no significant differences between groups in Vo2peak (156.1 ± 11.5 ml/kg/min vs 152.6 ± 5.4 ml/kg/min in Groups L and S, respectively), slope for Vo2 and speed, HRpeak (224.0 ± 6.4 beats/min vs 227.2 ± 6.8 beats/min in Group L and Group S, respectively), or LApeak (15.2 ± 3.2 mmol/l in Group L vs 13.6 ± 3.1 mmol/l in Group S). These results indicate that, in the case of low intensity cantering of 8-week training, differences in training distance do not significantly affect the degree of improvement in aerobic work capacity in the young Thoroughbred horse.
To reduce the intervals from Parturition to conception in normal multiparous mares and to promote the fertility in mares with reproductive failures, 13 mares, a total of 17 cases, were intramuscularly injected with prostaglandin F2α (PG) in the luteal phase. Ten mares came into estrue after the first injection of 5 mg of PG, whereas 3 mares required two or three PG treatments to induce estrus. Estrus was induced 5-8 days after PG treatment in 10 out of 14 cases that showed signs of estrus. The duration of estrus was 3.9 days on the average and 11 out of 17 cases ovulated 8-12 days after PG treatment. The number of matings was 1-5 times during the induced estrus and 11 mares conceived. A “star-like layering of the folds” in the uterine cavity appeared 2-6 days after PG treatment, and then disappeared 1-2 days before ovulation on ultrasonic monitoring. The plasma levels of progesterone (P) rapidly decreased following PG treatment, whereas the plasma levels of inhibin (INH) and estradiol-17β (E2) increased after PG treatment. The plasma concentrations of LH gradually increased following PG treatment and typical prolonged LH surges were observed during the periovulatory period. In contrast, the plasma concentrations of FSH decreased after PG treatment, followed by an increase after ovulation. There was an inverse relationship between the plasma concentrations of FSH and INH. The results of the present study clearly demonstrated that treatment with PG is a useful method for reducing the intervals from parturition to conception in multiparous mares, and for improving reproductive efficiency in mares with reproductive failure.
Field application of an indirect enzyme-linked immunosorbent assay for screening for an equine infectious anemia (EIA) antibody to p25 antigen by means of a robot system was performed. This system has been utilizing for quarantining racehorses in the facilities of the Japan Racing Association since 1994 because finding are obtained rapidly. The results can be obtained within 2.5 hr. with this system. Every one of 500 normal racehorses was negative with this system, but they included 31 sera showing a non-specific precipitin line on agar gel immunodiffusion test (AGID). On the other hand, only 2.9% of 775 non-specific sera on AGID were positive with this system. Conversion of optical density was observed by retrospective investigation of the sera from ELISA positive horses. The substances that cause false positives with this system and AGID were identified as bovine serum albumin and transferrin by immunofixation electrophoresis and AGID. The optical density of the false positives was reduced by adding bovine serum albumin or transferrin to the diluent of the samples. In view of these results, it has been suggested that the system is highly reliable for screening in EIA field surveys.
Colostrum samples were collected from 12 Throughbred mares (6-15 years old) at 3 farms located in Hidaka district, Hokkaido, Japan, to clarify the effects of rations and age on calcium, copper and zinc concentrations in mare’s colostrum. Average concentrations of all colostral calcium, copper and zinc were 82.8 mg/dl, 0.82 ppm and 7.76 ppm, respectively. Calcium, copper and zinc contents of rations for mares before parturition varied with the farms. However colostral calcium, copper and zinc concentrations were not different among the farms. There were significant negative correlationships between age of mares and colostral copper or zinc concentrations. It is suggested that copper and zinc intakes of the newborn foals born from older dams may diminish.
In order to obtain the epidemiologic churacteristics of equine respiratory disease associated with transport, a total of 29 Anglo-Arab and Thoroughbred horses were transported by truck for 1, 708 km. The horses were examined to determine whether a clinical relationship existed between respiratory disease, and the following intrinsic and extrinsic factors; breed, sex, position in vehicle, travelling time, weight loss during transit, food and water intake throughout the transport, nervous excitability and anaerobic efficiency. As travelling time increased, the number of horses which developed respiratory disease increased. However, no significant relationship existed when other factors were compared to the onset of equine respiratory disease.