Browsing by Author "Chin YY"

Now showing 1 - 7 of 7
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    Applying equineRSU and seasonal livestock correction to wider equine stud farm types
    (Taylor and Francis Group, 2024-09-12) Chin YY; Airey H; Horne DJ; Gee EK; Back PJ; Sclater J; Rogers CW; Sneddon N
    To adjust for potential overestimations in the nitrogen excretion by horses within Overseer®, a revised stock unit system has been proposed (equineRSU). These equineRSU were generated and validated using a medium-sized equine farm as a model farm. The aim of this study was to test the application of the equineRSU and seasonal stock number adjustment on a more complex farming model. Livestock numbers and management data were captured prospectively for the base property (128.8 ha) of a large multi-property commercial breeding stud (3 support properties, 556 ha total area) between June 2022 and May 2023. The monthly on-farm metabolisable energy (ME) requirement and pasture demand were deterministically modelled with both a customised feed budget using livestock class and weight or using the equineRSU and monthly adjusted stock numbers. There were multiple complex movements of horses on and off the property in the different stock classes across the year, with stock management reflecting seasonal periods of high stocking density. There was good agreement (6% variance) between actual ME demand (complex feed budget) and estimated feed demand (simplistic equineRSU model) of 4,387,187 MJ vs 4,102,770 MJ. This suggests that the equineRSU could be used on complex equine farm systems within Overseer®.
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    Career profile and pattern of racing for Thoroughbred jumps-racing horses in New Zealand
    (CSIRO Publishing, 2024-04-23) Gibson MJ; Legg KA; Gee EK; Chin YY; Rogers CW; Bryden W
    Context Racing structure and focus for racehorses differs across jurisdictions and is poorly described. In New Zealand and Australia, jumps racing accounts for a small proportion of total Thoroughbred races each year, as opposed to the larger jumps-racing (National Hunt) industry with purpose-bred horses found in the UK and Ireland. Aims This study aimed to describe the career profile and pattern of racing for Thoroughbred jumps-racing horses in New Zealand. Methods Metrics from every horse with a full jumps-racing career (n = 1276, 89% geldings) between the 2005/06 and 2021/22 racing seasons (n = 40,302 starts) were examined. Descriptive statistics, box plots and heat maps were used to describe the data, by using horse age as a proxy for career progression. Key results Jumps-racing horses had a median of 17 flat starts (IQR 9–30) before their first jumps-racing start. The median career of a jumps-racing horse was 3.7 years (IQR 2.3–5.2) and 29 starts (IQR 16–44). Older horses had a decreasing number of flat-racing starts and an increasing proportion of steeplechase-racing starts. However, the majority of horses still had at least one flat-race start per calendar year, often prior to the first jumps race. Most horses had one spell each season (length 194 days, IQR 124–259), and a condensed preparation length over the winter months, with a median of 14 days (IQR 10–21) between starts. Conclusion The career pattern for jumps-racing horses in New Zealand reflects the industry retention of horses with a prior career in flat racing into a secondary jumps-racing career. Successful horses have increased focus on preparation for the winter jumps-racing season. Implications Jumps racing provides a secondary racing career for some flat-racing horses, particularly geldings. This strategy reduces wastage of horses from the industry.
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    Condition-dependent maternal sex allocation in horses can be demonstrated using a biologically relevant, multivariable condition measurement
    (John Wiley and Sons, Inc., 2024-02-01) Chin YY; Rogers CW; Gee EK; Stafford KJ; Cameron EZ; Nichols H; MacLeod K; Palmer M
    Maternal condition is influenced by multiple variables that individuals experience at seasonal and local levels, and thus condition-dependent sex allocation is likely also multifactorial. Here, we test the Trivers-Willard Hypothesis (TWH) using a multivariable approach on a dataset of thoroughbred mare breeding records. There is no sex ratio variation when examined at univariable level, mirroring the usual approach to test condition-dependent sex allocation. Conversely, the multivariate model shows multiple variables interact to influence the likelihood of producing a male. Mare and management variables that represent better body condition is associated with an increase in likelihood of a male offspring. The magnitude and direction of sex ratio skew correspond closely with predicted mare energy balance, consistent with TWH predictions. Our findings therefore support the TWH and show that, while sex allocation is multifactorial, maternal energy status emerges as the dominant driver. The additive and agonistic interactions of different variables demonstrate that a multifactorial approach should be a key consideration in sex allocation studies.
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    Physical Fitness of Thoroughbred Horse Racing Jockeys
    (Springer Nature, 2023-10-30) Legg KA; Cochrane DJ; Gee EK; Chin YY; Rogers CW
    Purpose Thoroughbred racing jockeys compete at maximum physiological capacity in a sport with a high risk of falls and injury. A greater understanding of the physical capacities determining jockey performance may lead to minimum physical performance parameters and corrective interventions to improve jockey fitness and performance and reduce jockey and horse injury. The aim of this study was to develop appropriate physical testing procedures for jockeys and a physical fitness profile for different licence levels. Methods Fifty-eight jockeys (n = 24 females, n = 34 males), representing all apprentice jockeys licenced in New Zealand in 2021 (100%, n = 8 probationers and n = 39 apprentices) and eleven professional jockeys (14%) were assessed to determine baseline physiological and fitness data. Descriptive statistics and boxplots were used to compare aerobic fitness, abdominal (core), upper and lower body strength, muscular power, reaction time, flexibility and a novel ‘saddle’ test targeting lower body strength, balance, and endurance between licencing levels. Effect Size (ES) was used to determine magnitude of differences between groups. Results More experienced jockeys had greater relative lower body strength (ES = 0.2–0.7) and better balance (ES = 0.5–0.9) compared to the less experienced groups. Jockeys who were in the top 20 of the premiership table (jockey rankings) had faster reaction times (ES = 0.7) and greater core extensor strength (ES = 0.7) than other cohorts. Most tests showed little differentiation between jockey licence levels, however the ‘saddle test’ showed greater variability in the less experienced race riders. This test may be an effective measure of jockey baseline performance. Conclusions These data could be used to inform minimum jockey licencing requirements and future physical fitness training programmes to increase jockey physiological fitness, thereby minimising risk of falls or injury due to physiological deficits and performance.
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    Quantification of relative stock units for horses to permit correct application within pasture-based production systems
    (CSIRO Publishing, 2023-05-29) Chin YY; Back PJ; Gee EK; Horne DJ; Rogers CW; Bryden W
    Context. Overseer® is the primary software tool used to estimate farm-level nutrient cycle and management for regulatory purposes in New Zealand. The model compares feed demand among different livestock by using ‘revised stock units’ (RSUs, the annual energy requirement of a mature ewe to raise a single lamb to weaning; 6000 MJ metabolisable energy). The RSUs for several common equine stock classes are not yet available, while those currently available within the model are based on the linear scaling of feed demand to liveweight, which does not consider allometric scaling of metabolism to liveweight or the differences in digestive physiology and nutrient metabolism between ruminants and monogastric hindgut fermenters (horses). Aim. To compare the current RSU values used in Overseer® for different equine stock classes, with the equineRSU values calculated using equine-specific models. Methods. Weighted average estimates of the bodyweight for the different equine livestock classes were calculated from the published literature. These weighted average estimates of bodyweight were used to estimate the energy requirements on the basis of data published by National Research Council. The resulting dry-matter intake and N intake from the equineRSU values and the current RSU values in use within Overseer® were modelled using published data on diet composition, crude protein content and the digestibility of the different feeds offered. Results. The current RSUs in Overseer were 2.5–6.8 units higher than the equineRSU values obtained from the equine-specific models. This overestimation in feed demand resulted in N-intake estimates at an animal level being 52–108% higher than values derived using the equine-specific estimates. Conclusion. The use of RSUs based on linear scaling of feed demand from ruminants on the basis of liveweight overestimates feed demand and N intake in horses. If horses are to be included within nutrient management models, feed demand must be based on published equine data for energy requirements to avoid over-inflation of N excretion. The equineRSUs calculated in this study reduce the risk of over-inflation of N intake and excretion, and subsequently the N leaching estimations. Implication. Failure to accurately model feed demand of horses within nutrient management software would unfairly compromise stocking density and horse management on large commercial breeding farms. The implication for these errors on economic impact and restricted livestock number is greatest for the Thoroughbred breeding industry due to the scale of the operations.
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    The pattern of breeding and management within the New Zealand Thoroughbred breeding industry 2005-2015. (II) The mare population
    (CSIRO Publishing, 2024-01) Chin YY; Rogers CW; Gee EK; Stafford KJ; Cameron EZ
    Context: The New Zealand Thoroughbred breeding industry is heavily focused on producing horses for the export market and there has been a reduction in the number of horses racing in the past 20 years. The impact of these production constraints, and changes in production focus, have not been described at a national herd level. Aim: To describe the breeding management, reproductive performance, and careers of the New Zealand Thoroughbred broodmare herd during the 2005/06-2015/16 breeding seasons. Methods: The demographics, population structure, reproductive efficiency, breeding management and career descriptors of Thoroughbred mares were examined using descriptive analysis. Gestation length was modelled using a linear mixed effects model. The impact of different variables on breeding career were quantified by calculating odds ratio. Results: There was a consistent reduction in the size of the national broodmare herd over the 10 years investigated. Half of the mares not retained for breeding were mares that were breed to low-cost stallions. Despite a short (∼100 days) commercial breeding season few (20%) mares were mated early in the season (September), with most mating (70%) occurring between October and November. The 27 days mean foaling to conception interval (FCI) suggests that FCI was artificially shortened and most pregnancy was achieved within first oestrus cycle post-partum. Mare career length and lifetime productivity was positively associated with the stud fee of the first stallion that the mare was mated to and number of foals registered for racing. Conclusion: Mare replacement and loss within the national herd was disproportionately associated with mares that were producing foals for a contracting domestic racing market. There was a constricted breeding season with most mares being mated within the first oestrous cycle post-partum. Mare retention and breeding success were positively associated with the service fee of the sire and progeny that had raced, reflecting the commercial pressure of the industry on mare management. Implication: The changes in the broodmare herd and management reflects the increasing proportion of the industry focusing on breeding foals that will appeal to the export market. The economic drivers for early born foals provide management challenges as these are not aligned with the optimal reproductive season of the horse.
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    The pattern of breeding and management within the New Zealand Thoroughbred breeding industry 2005-2015. 1. the stallion population
    (CSIRO Publishing, 2024-01) Chin YY; Rogers CW; Gee EK; Stafford KJ; Cameron EZ; Bryden W
    Context: There has been a contraction within the New Zealand Thoroughbred racing industry and there are limited data demonstrating how this has affected, or been reflected, within the breeding industry that supplies horses for the racing industry. A reduction in the breeding industry, to a greater extent in the sector servicing domestic rather than export market has been speculated. Aim: To describe the demographics, breeding pattern, reproductive career and workload of New Zealand Thoroughbred stallions between 2005 and 2015. Methods: The breeding records of all Thoroughbred stallions covering >10 mares during 2005/2006-2015/2016 breeding seasons and the lifetime breeding records of all the mares covered by these stallions were extracted from the New Zealand Thoroughbred Racing website. The demographics, population numbers, career pattern, and 10-year trend in market share of stallions in different stud fee categories were examined using descriptive analysis. The stallion's reproductive workload was modelled deterministically. Results: The breeding population reduced over the 10 years examined (mares by 20%, sires by 32%). This industry consolidation was almost entirely due to the 50% reduction in the number of mares mated to the low-priced stallions, which generated horses for the domestic market. The relative proportion of mares sent to medium- and high-priced stallions (breed to sell and export sector) doubled. The commercial breeding career of low- and medium-priced stallions and shuttle stallions was short (4-5 years). The number of mares covered by a stallion increased with stud fee category. Stallions covered a greater number of mares in October and November than in September and December because of the restricted opportunity to cover foaled mares early in the season, caused by the long gestation length of mares and the need to cover mares before December. Conclusions: Findings in this study support that the contraction in the New Zealand Thoroughbred breeding industry was due to a reduction in the industry sector that focuses primarily on supplying horses for domestic racing. Commercial pressure and biological constraints heavily influenced the reproductive management of the breeding industry. The breeding management of stallions during the season is heavily influenced by stallion service fee category, which reflects his book size and the commercial appeal of the resultant progeny. Implications: The contraction within the domestic sector of the breeding industry was reflected in the concurrent contraction within New Zealands domestic racing population and fewer colts and geldings entering racing. Industry breeding trends demonstrate that economic viability and optimisation of revenue depend on the breeding industry focusing on the export rather than domestic market.