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    The effects of partial stable confinement on the voluntary activity of weanling thoroughbred foals : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science, Massey University, Palmerston North, New Zealand
    (Massey University, 2017) Lilly, Vanessa Maree
    This thesis discusses an observational study, which evaluates the effects of partial stable confinement on the voluntary activity of weanling Thoroughbreds kept at pasture. Despite the current knowledge identifying the need for early exercise and pasture access in young Thoroughbreds, there is little information on pasture activity, and none on the effects of partial stable confinement on the amount of, and type of, activity when at pasture. It has previously been stated that young horses confined to a stable at night, spend more time cantering and trotting in the paddock during the day, when compared to their unconfined counterparts- the authors suggested this may be compensation for the lack of activity carried out whilst in confinement. Unfortunately, no further research has been carried out to support this theory, and it is therefore unknown how much confinement is required before horses will carry out compensatory activity, and how length of confinement and the subsequent volume of compensatory activity may affect total average daily activity. A study was carried out on a small commercial Thoroughbred stud farm in the Manawatu, to determine the effects of partial stable confinement on the amount, and type of activity six weanling Thoroughbreds carried out on a daily basis. The horse’s remained under normal management conditions, and were kept at pasture, and confined in loose boxes for an average of three hours a day, on mornings decided by the Stud Master, for handling and yearling sales preparation. Activity was monitored for 141 days using a Heyrex biosensor. The sensor containing a tri-axial accelerometer was attached to each horse’s halter, and the data were recorded as Delta-G; the change in acceleration between respective samples. The data were recorded in 15 minute increments, resulting in approximately 576 records per day and possible 13,536 data points per horse (there was a range of 3,456 - 10,272 usable data points per horse). A total of 39,372 15-minute data points were used in the data analysis. Each horse’s activity profile, including total daily activity, average daily activity and proportion of highand low-energy activity, when at pasture and during confinement was analysed. Total average daily activity varied between horses (70,385 – 95,331, P<0.001), however each horse’s total daily activity was highly repeatable across days with no significant difference between horses between days. Partial confinement resulted in a reduction in average daily activity in all horses (67,682 – 84,737, P<0.0088), except Colt 3 who was more active during days of confinement, than on days of no confinement (89903±5073 and 84813±2163, respectively). Partial stable confinement had no significant effect on the proportion of total activity which was highenergy activity (8.69% on days of confinement, vs 12.23% on days of no confinement) except for Colt 3, who carried out a high proportion of high-energy activity during a day of confinement, then on a day of no confinement (18.23% vs 9.14% respectively). This may be a form of compensation, however it was only noted in one horse, and therefore is more likely to be a behavioural response to being isolated to a stable. The proportion of high-energy activity between the hours of 9am-12pm, when confinement would occur, was also not effected by confinement when compared to days of no confinement (8.64% vs 9.80%, respectively), except in Colt 2, who carried out no high-energy activity whilst in confinement between 9am-12pm. The partial confinement of these weanlings appeared to reduce their overall average daily activity, however it did not affect the amount of high-energy activity. Thus partial confinement may not restrict the all-important osteo-inductive high speed activity required to promote optimal musculoskeletal development in weanlings. However, we lacked the experimental design to examine if there was any association of length of confinement and any compensatory activity. Further studies should examine if the length of partial confinement alters the subsequent activity at pasture.
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    Flexural limb deformities in thoroughbred foals in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree Master of AgriScience (Equine) at Massey University, Manawatu, New Zealand
    (Massey University, 2014) Shotton, Amanda Kylie
    The aims of this thesis were to describe the descriptive epidemiology of congenital flexural limb deformities (FLD) in foals on commercial Thoroughbred stud farms, and to describe the management and treatment of these foals. Data were collected on five commercial Thoroughbred stud farms in the Auckland and Waikato regions. Data were collected primarily by stud farm personnel, and assisted by study personnel when on farm. Data were collected on a selective population of 203 foals during the 2013/2014 season. Pre-selection by stud farm personnel towards foals with FLD prevented the calculation of prevalence and resulted in 67% (135/203) of the foals with records having one or more FLD recorded. Laxity was observed to affect 87/135 foals, contracture of at least one joint region 57/135 foals and 6/135 foals were back at the knee; nine foals suffered from multiple forms of deformity. The median score for laxity was 2 (IQR 2-3) on a four point scale. The median score for contracture affecting hoof-ground contact was 2 (IQR 2-3) on a three point scale, while the median score for contracture affecting the fetlock and carpal regions was 2 (IQR 2-2). Multiple scorings over time were provided for 69/135 foals, 64 of these foals showed improvement in the severity of deformities by the final scoring. Inter-observer agreement (between study personnel) was strong when scoring flexural laxity (k=0.95), contracture affecting hoof-ground contact (k=1.00) and contracture in the joint regions (k=0.85). In contrast, inter-observer agreement between study personnel and stud farm personnel was lower when scoring flexural laxity (k=0.69) and when scoring contracture in the fetlock and carpal regions (k=0.14). Treatment data were provided for 40/135 foals. Confinement was the most common form of treatment provided for mild and moderate cases of flexural contracture and flexural laxity; severe cases of flexural contracture required more invasive forms of treatment in combination with confinement. Improvement in the severity of deformities was observed following treatment in 28/42 (67%) cases of contracture observed to effect hoof-ground contact, 33/43 (77%) cases of contracture affecting the fetlock and carpal regions and 36/56 (64%) cases of laxity. This thesis provides insight into the effect of FLD on Thoroughbred foals in New Zealand. The results indicate that foals tend to be mildly or moderately affected by FLD at birth and that treatment by stud farms is pragmatic.
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    Birth weight and growth of New Zealand thoroughbred foals : a thesis presented impartial [i.e. in partial] fulfilment of the requirements for the degree of Master of Veterinary Studies at Massey University, Palmerston North, New Zealand
    (Massey University, 2008) De Freitas Aiex, Luciana
    The success of the New Zealand Thoroughbred horse industry is highly dependant on the production of good foals. The birth weight of the foal, and its weaning weight, is closely associated with maternal factors, such as age, parity, size, and nutrition. Age is associated with endometrosis and limited placentation, which leads to a reduction in foal birth weight. Multiparous mares tend to produce larger foals than primiparous mares because of the priming effect that a first pregnancy has on the uterus. Nutrition affects the size of the mare, which is positively correlated with foal birth weight. The size of the mare is positively correlated with birth size of the foal, and the birth weight of the foal is positively correlated with the mass, gross area and volume of the allantochorion. and the total area of foetomaternal contact. The information available on the maternal effects on foal birth weight is limited. This study attempts to improve our understanding of this relationship by examining data collected from New Zealand Thoroughbred mares, which are held on pasture throughout the year and may receive little supplementary feed during pregnancy. Data were collected from 49 New Zealand Thoroughbred marcs and their foals during the 2004 foaling season. Analyses were conducted to determine whether the age, parity, body condition score, weight pre- and post-partum, and height of the mare, the length of gestation and the allantochorion weight and volume were associated with foal sex ratio (n = 49), foal wet birth weight (n = 27), day 1 weight (n = 49), and foal height (n = 49). The daily growth of a subgroup of 15 foals in their first two weeks of life was monitored. In addition, age and parity data was collected via the online Thoroughbred Studbook from 492 mares that were bred to one of the Waikato Stud stallions in the 2001 breeding season. The mean age of mares was 10.8 ± 0.8 years for the Newmarket Lodge population and 11.0 ± 0.2 years for the Waikato Stud population; the mean parity of mares was 4.5 ± 0.4 for the Newmarket Lodge population and 5.9 ± 0.2 years for the Waikato Stud population; and the mean length of gestation was 355.67 ± 1.26 days. The age and parity of the mare and the sex of the foetus had no significant effect on the length of gestation. Primiparous mares had significantly lighter and lower foals than multiparous mares, independently of the age of the mare. The mean wet birth weight of foals was 54.6 ± 1.1 kg and the mean day 1 weight was 55.7 ± 0.8 kg. The range of foal birth weights was from 41.0 to 66.5 kg. The sex of the foal did not significantly affect its wet birth weight and day 1 weight. The mean wet birth weight was 54.1 ± 2.1 for a filly, and 55.0 ± 1.3 for a colt. The mean day 1 weight was 55.2 ± 1.4 for a filly and 56.2 ± 1.1 for a colt. The relationship between the wet weight of the foal and its day 1 weight was highly significant. Mare age and parity affected the weight and volume of the allantochorion. The allantochorions of primiparous and multiparous mares aged 16 years and over were lighter and had lower volumes than those of multiparous mares aged five to 15 years. There was no difference in the weight and volume of the allantochorions of primiparous mares and multiparous mares aged 16 years and over. The mean weight of the allantochorion was 3.68 ± 0.09 kg. and the mean volume was 2.86 ± 0.07 litres. The weight and volume of the allantochorion were significantly associated with the wet birth weight and day 1 weight of the foal. Moreover, the weight of the mare pre- and post-partum significantly affected the wet birth weight, the day 1 weight, and the height of the foal. Mares lost an average of 80.9 kg liveweight with the foaling process. Foals lost on average 1.17 ± 0.94 kg between the wet birth weight and day 1 weight measurements. Seventy percent of foals lost weight between these measurements. The average daily weight gain of foals from day 2 to day 14 of life was 1.71 ± 0.11 kg. The average weight gain of foals was 25.05 ± 1.02 kg in the first 14 days of life. The mean height of foals at birth was 1.028 ± 0.008 m and they grew on average 0.062 ± 0.005 m to reach a mean height of 1.087 ± 0.005 m at two weeks of age. The average daily height increase from day 1 to day 14 was 0.004 ± 0.002 m. There was no significant influence of the sex of the foal on the weight gain and height increase from day 1 to day 14. although the mean wet birth weight, day 1 weight and day 14 weight of colts is slightly higher than that of fillies. Maternal factors influence the birth size of the NZTB foal born to mares kept on pasture. The weight of the mare is closely associated with the size of the allantochorion. which is significantly associated with the birth weight of the foal. Primiparous and older mares (≥ 16 years) produce smaller foals than multiparous mares younger than 16 years. Foals lose weight in the first 24 hours after birth. This early neonatal weight loss probably occurs because of drying off. The sex of the foal did not affect the length of gestation, and it did not influence the birth weight of the foal and its daily growth in the first two weeks post-partum. The information in this study has not been previously reported for horses in New Zealand.
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    Aspects of growth and development of the pasture-fed thoroughbred foal in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand
    (Massey University, 2003) Gee, Erica Kathleen
    In each of 2 years, pregnant mares (n = 10 and n = 23) kept at pasture were divided into copper supplemented or unsupplemented groups, and injected with calcium copper edetate or saline. Their foals were examined, weighed, measured and clinically scored at 2 weekly intervals from birth to 160 days of age to assess growth and development, and evidence of developmental orthopaedic disease (DOD). Foal liver biopsies were harvested by Tru-cut biopsy needle at different ages for determination of copper concentration. At 160 days of age, articular surfaces were examined for cartilage irregularities, which were sampled for histology and histochemistry. Cartilage samples were harvested from irregularities and defined sites for histology. Distal third metacarpal and metatarsal bones (Mc3 and Mt3) were sawn frontally, radiographed and processed for histology. The parenteral copper supplementation had no effect on mare or foal liver copper concentration, and was not associated with reduced evidence of DOD in foals. The prevalence and severity of DOD lesions was very low. Two different patterns of decline in foal liver copper concentration were observed. Enlargements of the distal Mc3 and Mt3 physeal region were present in all foals, but were not associated with pain, lameness, or abnormalities in the metaphyseal growth plate. In vivo techniques to assess body composition could be used to predict chemical body composition, particularly ultrasonographic rump fat thickness measurements. Fillies were significantly fatter than colts at 160 days of age, despite no differences in mean birth weight and weight gain. The only growth parameters associated with the prevalence of DOD lesions was rapid growth rate between 5 and 6 months of age, which was associated with more lesions in the tibiotarsal joint. The New Zealand Thoroughbred industry should weigh and condition score foals at monthly intervals, keeping careful records. Foals can be successfully raised at pasture, with good growth, and a low incidence of DOD lesions at 160 days of age, without being excessively fat. Copper injections should not be given to horses, but oral supplementation with copper should be considered for pregnant mares in late gestation