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    Investigating the pathogenesis of catastrophic humeral fractures in dairy heifers in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2022) Wehrle Martinez, Alvaro Sebastian
    Catastrophic outbreaks of spontaneous humeral fractures in dairy heifers in New Zealand have given rise to animal welfare problems and resulted in significant economic losses to the New Zealand dairy industry. Preliminary small sample size studies have identified potential causes and/or factors associated with the occurrence of humeral fractures including periods of protein-calorie malnutrition, increased osteoclastic bone resorption related to lactation, and low liver and/or serum copper concentration (suggestive of periods of copper deficiency). Nevertheless, outbreaks of humeral fractures still occur throughout New Zealand with devastating consequences. Therefore, the main objective of this thesis was to investigate the likely causes and/or major risk factors associated with the occurrence of spontaneous humeral fractures in dairy heifers in New Zealand and propose a likely pathogenesis of the condition. For this, a large cohort of bone samples (humerus and ribs), as well as liver and blood/serum samples were collected from 2-year-old dairy heifers that suffered spontaneous humeral fracture post calving (affected heifers) for comparison with age-matched post-calving heifers with no bone fractures (control heifers). Blood/serum samples, used for the determination of biochemical profile in affected heifers, showed increased B -hydroxybutyrate and decreased creatinine concentration indicative of negative energy balance and/or periods of undernutrition. Bone samples were used for gross, histologic, histomorphometric, Raman and Fourier transform infrared spectroscopic analysis as well as for the measurement of the collagen and collagen crosslink content in bones from affected heifers compared with control heifers. Histologically affected humeri had osteoporosis (reduction in trabecular volume with abnormal trabecular architecture, thicker growth plates with abnormal architecture, increased resorption in the distal humerus, and a thinner cortex with increased and abnormal resorption. Abnormal cortical resorption increased the probability of fracture 54.2 times and reduced trabecular density 249.5 times. Spectroscopic analysis indicated decreased bone quality in the humeri from affected heifers with a reduced amount of bone organic and mineral components, lower mineralisation, lower carbonate substitutions, increased bone remodelling, and reduced mineral crystallinity. Analysis of collagen content and collagen crosslinking using liquid chromatography indicated reduced total collagen content and increased collagen crosslinking in the humeri from affected heifers. Finally, a survey was conducted using farms that have and have not had a case of humeral fractures showed Holstein-Friesian Jersey cross breed was a possible risk factor. The likely causes and/or major risk factors associated with the occurrence of spontaneous humeral fractures in dairy heifers in New Zealand include breed, protein-calorie undernutrition during important bone growth periods (which significantly affected the bone chemical composition and architecture) and increased abnormal bone resorption. These factors have significantly compromised bone mechanical strength and led to the spontaneous humeral fracture.
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    The relationship between nutritional adequacy and 24-month fracture occurence in Māori and non-Māori of advanced age : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Nutrition and Dietetics, Massey University, Albany, New Zealand
    (Massey University, 2015) Towgood, Alice
    Abstract Background The life expectancy of both Māori and non-Māori is continually increasing with more New Zealanders expected to live into advanced age. Adults over the age of 80 experience greater health loss than any other age group, with chronic disease and associated disability increasing substantially with age. Osteoporosis and the morbidity associated with fractures, particularly hip fracture, are of critical concern for an ageing population and may diminish quality of life and independence for older people, thus placing an increased burden on health and disability support services. The role of nutrition in the maintenance of bone mineral density (BMD), bone integrity, and subsequent fracture prevention, particularly in octogenarians is unclear. The ability to meet adequate energy requirements decrease with increasing age and may compromise intake of nutrients related to bone health. Nutrients necessary for bone health including: protein, calcium, vitamin D, phosphorous, magnesium and potassium are modifiable factors. Achieving optimal bone nutrient intakes may influence potential for maintenance of good bone health in adults of advanced age. This study aims firstly to investigate food and nutrient intakes of Māori and Non-Māori octogenarians to establish an understanding of nutrient adequacy. Secondly, to investigate the energy and nutrient intakes of participants who experience a fracture compared with those non-fractured to identify nutrient specific risk factors for fracture in adults of advanced age. Method Comprehensive nutritional parameters were collected using two separate 24-hour multi-pass recalls. FOOD files were used to analyse food sources and nutrient intake. Face to face interviews were conducted to ascertain specific social, demographic, health and fracture information. Fracture occurrence was measured over a 24 month period following the 2 x 24-hour Multi Pass Recall’s and included self-reported and hospitalised fracture occurrences. Hospitalisation data was obtained with permission from the participants. National Health Index New Zealand (NHI) numbers were used to identify fractures. Results There were 317 participants (113 Māori and 204 non-Māori), aged 80-90 years in this study. For men and women respectively the median energy intakes were 6,943kJ vs. 5,603kJ for Māori; and 8,203kJ vs. 6,225kJ for non-Māori; protein as a percentage of energy was 15.5% vs. 15.9% for Māori and 15.7% vs. 15.5% for non-Māori. The top foods contributing to energy were bread, butter and margarine for all Maori and non-Maori with beef and veal contributed the most protein for Māori men, bread for Māori women and milk for non-Māori, men and women. Compared to the Estimated Average Requirement (EAR) intakes of calcium, vitamin D, magnesium and potassium were inadequate for all participants. Compared to an EAR of 1100mg for men and women, median calcium intakes were low, 559mg vs. 539mg for Māori and 748mg vs. 672mg for non-Māori, men and women respectively. The primary food groups contributing to calcium were milk, cheese and bread. Compared to the EAR (15 μg/day in men and women) and vitamin D intake from food was low (≤ 4 μg) for all participants. Compared to the EAR (350mg/day men and 265mg/day women), median magnesium intakes were 259 mg/day vs. 204mg/day for Māori and 271 mg/day vs. 238 mg/day for non-Māori, men and women respectively. The primary food groups contributing to magnesium were bread, breakfast cereals and fruit. A total of 18.6% of Māori and 20.6% of non-Māori sustained a fracture over a 24 month period. One in five Māori and non-Māori women sustained fractures. Among non-Māori women those who fractured were 1.1 times more likely to be financially insecure than non-fractured women (p=0.033). For Māori women who were fractured, inability to afford to eat properly was 3.3 times more likely (p=0.012), and previous fractures were 1.5 times (p=0.015) more likely than for non-fractured women. Fractured Māori women consumed significantly less vitamin D (2.0μg vs 3.0μg) (P=0.01) and magnesium (143.0mg vs 211mg) (P=0.033) compared to non-fractured Māori women. Conclusion Energy intakes were low for all participants and may have manifested the suboptimal intakes of calcium, vitamin D, potassium and magnesium prevalent in Māori and non-Māori, men and women. Fractures were more frequent in women than men, and both Māori and non-Māori sustained similar rates of fracture over the 24 month period. Magnesium and vitamin D intakes were significantly related to fracture occurrence in Māori women; this relationship diminished with further regression analysis. Increased intake of energy in adults of advanced age, with a focus on protein rich and nutrient dense foods, particularly calcium and magnesium, should be encouraged through consuming a variety of foods from the major food groups. Greater intakes of calcium can be achieved through higher consumption of milk and dairy products including yoghurt and cheese; and magnesium through increased green leafy vegetables, seafood, dairy, mushrooms, avocado, beans and bananas. Vitamin D intakes were minimal from food; however it is possible participants were receiving supplementary vitamin D and further investigation is warranted. For fractured Māori women, magnesium intake was significantly lower than those with no fractures. Promoting increased intakes of culturally acceptable foods such as vegetables and seafood may be advantageous to increase magnesium intakes.
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    The quantitative assessment of photodensity of the third carpal bone in the horse : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2000) Secombe, Cristy Jane
    The purpose of this study was to determine if a method of non-invasive bone mineral analysis could be adapted to quantitatively assess photodensity in the third carpal bone of the horse. The technique chosen was radiographic absorptiometry which determines bone mineral density from a radiograph that includes a control (usually a wedge) of known photodensity. When taken correctly the tangential view of the distal row of carpal bones allows visualisation of the dorsal aspect of the third carpal bone, without superimposition of overlying structures. The method is technically demanding, because the angle at which the x-ray beam penetrates the third carpal bone can not be exactly replicated in a clinical situation, as it is affected by the x-ray beam angle and the limb flexion angle. To utilise radioabsorptiometry in the tangential view assessment of the effect of variation in x-ray beam angle was required. Fourteen isolated distal rows of carpal bones were radiographed varying the x-ray beam angle in 5° increments over 15° from the base angles of 60° and 90°. The radiographs were digitised and processed to determine the photodensity of specific regions of interest in terms of millimetres of aluminium, using the wedge as reference. The results indicated that small variations in x-ray beam angle significantly affect photodensity. Quantitative assessment of the photodensity of the fourth carpal bone showed changes associated with exercise, similar to those in the third carpal bone. Changing the size of the region of interest when x-ray beam angle was varied by 30° did not affect photodensity of the region of interest. Although conversion from photodensity to bone mineral density was not possible within this project, the findings supported other authors who have studied bone mineral density of the third carpal bone. There are two tangential views of the distal row of carpal bones. The two methods affect the radiographic image differently because the magnification and distortion changes are different in each and this precluded accurate comparison. Therefore, it was impossible to determine which method would more accurately assess the photodensity of the third carpal bone. The study concluded that quantitative assessment of photodensity of the third carpal bone using either tangential view was clinically inapplicable at this time, because of the significant effect of very small changes in angle on photodensity. This is unfortunate, because the current practice of visual subjective assessment of photodensity of the third carpal bone remains unsatisfactory, in particular the differentiation between grades of sclerosis.