Epidemiological studies of early exercise and measures of training and racing performance in thoroughbred racehorses : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Epidemiology, Massey University, Palmerston North, New Zealand
This thesis includes a series of epidemiological studies conducted to quantify the exercise regimens of Thoroughbred yearlings during their sales preparation and 2- and 3-year-old race training. Additionally, this thesis aims to establish if there are associations between the exercise regimens and training and racing performance at two years of age.
Cross-sectional and cohort studies quantified the components of the exercise regimens used during sales preparation on stud farms in New Zealand. Exercise was a common practice during sales preparation. The type and amount of exercise was often tailored to individual horses. Overall, exercise varied by gender, the month of preparation, and between farms indicating that the exposure to exercise during sales preparation was not the same for all horses.
Survival analysis identified different horse and exercise risk factors for voluntary, involuntary, and musculoskeletal interruptions during training. Specifically, there were strong associations between increased total hand walking time and reduced chance of voluntary interruptions, and more time walking on a mechanical walker increased the risk of involuntary interruptions. Other horse and training factors, such as trainer, gender, age at the start of training, and the distance accumulated at canter and high speed, were associated with the time to interruptions during training.
Interruptions before the first trial were associated with an increased time to the first trial or race and a decreased chance of starting in a trial. Accumulating shorter distances and fewer events at high speed were both associated with a decreased chance of a trial or race start. Longer distances accumulated at high speed were associated with a decreased time to the first trial. No associations were found between the exercise accumulated during sales preparation and the time to the first trial during training. Overall, the exercise accumulated during sales preparation was associated with a measure of training performance, whilst the timing of interruptions and the accumulation of exercise during training have implications for reaching important training and racing milestones. The results of this thesis indicate that current exercise regimens could be modified to enhance the training and racing performance of Thoroughbred racehorses.
Links to published versions of articles: Bolwell, C.F., Rogers, C.W., Firth, E.C. & French, N.P. (2010a). Management and exercise of Thoroughbred yearlings during preparation for yearling sales in North Island of New Zealand. Proceedings of the New Zealand Society of Animal Production, 70, 157-161. Retrieved from http://nzsap.org.nz.
Bolwell, C.F., Rogers, C.W., Firth, E.C. & French, N.P. (2010b). Management and exercise of Thoroughbred yearlings during preparation for yearling sales. Proceedings of the 18th International Conference of Racing Analysts and Veterinarians Queenstown, New Zealand.
Bolwell, C.F., Rogers, C.W., Firth, E.C. & French, N.P. (2010c). Identification of three distinct sub-populations of 2-year-old racehorses in training. Proceedings of the 18th International Conference of Racing Analysts and Veterinarians Queenstown, New Zealand.
Bolwell, C.F., Rogers, C.W., French, N.P. & Firth, E.C. (in press). Risk factors for interruptions to training occurring before the first trial start of 2-year-old Thoroughbred racehorses. The New Zealand Veterinary Journal.
Bolwell, C.F., Rogers, C.W., French, N.P. & Firth, E.C. (2011a). Exercise in Thoroughbred yearlings during sales preparation: A cohort study. Equine Veterinary Journal, 44(1), 20-24. doi:10.1111/j.2042-3306.2011.00370.x.
Bolwell, C.F., Rogers, C.W., French, N.P. and Firth, E.C. (in press). Associations between yearling exercise and interruptions to race training in Thoroughbred racehorses. American Journal of Veterinary Research.
Bolwell, C.F., Rogers, C.W., French, N.P. and Firth, E.C. (2011b) The effect of interruptions during training on the time to the first trial and race start in Thoroughbred racehorses. Manuscript submitted.for publication.