Browsing by Author "Rogers C"

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    Jockey Career Length and Risk Factors for Loss from Thoroughbred Race Riding
    (MDPI (Basel, Switzerland), 2020-09-10) Legg K; Cochrane D; Gee E; Rogers C
    Professional thoroughbred racing jockeys repeatedly work close to physiological capacity during races, whilst maintaining low body weights, on a daily basis with no off-season. The effects of this on their career length is unknown. The aim of this study was to examine the career lengths and reasons for loss from the industry of 674 jockeys and apprentices who rode over 14 racing seasons and 421,596 race day starts in New Zealand. Descriptors were compared between jockeys in short (1–2 years), middle (3–9 years) and long (>10 years) career cohorts with descriptive statistics and Kaplan–Meier survival curves. The median career length for jockeys was 2 years (IQR 1–6). Long career cohort jockeys (11%) had lower carried weights (IQR 56–57 kg, p = 0.03), 40 times the median number of rides per season (248, IQR 61–434, p < 0.001), half the rate per 1000 rides of falling (1.1, 95% CI 1.0–1.2, p = 0.009) and 1.3 times the rate of winning (100, 95% CI 99–101, p < 0.01) than jockeys in the short career cohort. Jockeys who rode over 200 races per season had careers three times longer than jockeys with fewer races per season (p < 0.001). Half of the 40% of jockeys who failed to complete their apprenticeship were lost from the industry in their first year of race riding. In conclusion, most jockeys had short careers where the workload of a jockey and their ability to obtain rides had greater impact on career longevity than their performance.
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    The Effect of Sex and Age on Bone Morphology and Strength in the Metacarpus and Humerus in Beef-Cross-Dairy Cattle
    (MDPI (Basel, Switzerland), 2021-03-05) Gibson M; Hickson R; Back P; Dittmer K; Schreurs N; Rogers C
    In cattle, limited data have been reported about the relationship between live weight, bone size, and strength and how this relationship can be altered by factors such as sex and age. The aim of this study was to describe the relationship of peripheral quantitative computed tomography (pQCT)-derived parameters of bone strength and morphology with live weight, age and sex in beef-cross-dairy cattle. All animals were weighed the day before slaughter. The metacarpus and humerus were collected at slaughter and scanned at the mid-diaphysis using pQCT. Live weight was the primary explanatory variable for bone size and strength in all cohorts. However, the effect of age was significant, such that magnitude of response to liveweight was less in the 24-month-old cohort. Sex was significant within cohorts in that bulls had a shorter metacarpus than steers and heifers had a shorter metacarpus than steers at age of slaughter.
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    The Mid-Diaphysis Is a Poor Predictor of Humeral Fracture Risk Indicating That Predisposing Factors Are Recent
    (MDPI (Basel, Switzerland), 2021-09) Gibson M; Dittmer K; Hickson R; Back P; Wehrle-Martinez A; Rogers C; Bonanno A
    The incidence of spontaneous humeral fractures in first-lactation dairy heifers in New Zealand has emphasised the need to understand the thoracic limb bone growth of dairy heifers. Previous research has indicated that a predisposing factor to spontaneous humeral fracture is nutrition. In addition, it has been hypothesised that liver copper concentration affects bone strength and may be a potential factor associated with humeral fracture risk. The aim of this study was to compare bone morphology in the mid-diaphysis of the metacarpus and humerus of heifers affected and unaffected by spontaneous humeral fractures, and determine the effect of copper status at death on bone morphology. The metacarpus and humerus were collected from heifers affected and unaffected by humeral fractures, and scanned using peripheral quantitative computed tomography (pQCT). The mid-diaphysis of the humerus of the affected group had reduced cortical bone mineral density and a trend for reduced cortical content and total bone content, which contributed to a reduced stress–strain index. The trend for reduced bone length in affected humeri provides additional support for the hypothesis of inhibited humeral growth. Heifers with low copper liver concentrations had reduced humerus lengths and reduced cortical bone mineral densities. These data support the hypothesis that the developmental window for humeral fracture is recent, and possibly associated with periods of inadequate nutrition.