Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

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Author: search.filters.author.Rogers CWSubject: search.filters.subject.breeding

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    The genetic parameters of racing success and longevity in the New Zealand Thoroughbred racing industry
    (Taylor and Francis Group on behalf of the Royal Society Te Apārangi, New Zealand, 2025-04-23) Chin YY; Sneddon NW; Gibson MJ; Legg KA; Gee EK; Rogers CW; Handcock R
    Within the Thoroughbred industry, individual success can be measured with races and prize money won. At an industry level, there is a requirement for horses to be able to race from a young age and have a sustained injury-free career. Therefore, the variance components of such traits were investigated within ASReml for 26,920 New Zealand Thoroughbred racehorses. Age at first competitive high-speed event (trial or race start) had high heritability (h2= 0.52 ± 0.02), and an inverse genetic correlation with career earnings (−0.40 ± 0.05) and number of wins (−0.35 ± 0.06). Career earnings (h2 = 0.24 ± 0.02) had positive genetic and phenotypic correlations (0.59 ± 0.004) with career length, implying that racing success could be a useful selection proxy for career length. Horses that started earlier had longer career length (−0.21 ± 0.07,–0.18 ± 0.01). The low heritability of career length (0.11 ± 0.01) reflects considerable environmental influence on this trait, reinforcing the importance of early training and exercise in increasing career length. Therefore, the optimal strategy is a selection programme focusing on racing success, which improves commercial appeal and is genetically correlated with longevity. A training and racing programme that encourage an early competitive high-speed event would optimise the phenotypic development of the musculoskeletal system and reduce injury risk.
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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.