Vitamin A has been studied intensely in its application to the fields of animal and poultry nutrition. Over forty years of investigation have provided extensive data on the chemistry, analysis, deficiency symptoms and nutritional requirements of vitamin A. However, there is still a scarcity of information concerning its mode of action in the body, particularly regarding carotenoid conversion to vitamin A and its absorption, transport, storage and association with disease. As recently as twenty years ago, fish liver oils and alfalfa meals were the major sources for vitamin A supplementation. These natural concentrated sources varied in potency and activity from one batch to another. Some contained impurities which interfered with assays and contributed to the instability of vitamin A activity.

It has long been known that natural or synthetic oxytocin, whether it be endogenous or exogenous, causes a change in the motility pattern of the female genital tract and the let-down of milk in laboratory and farm animals. The important functions in animal reproduction such as sperm transport in the female tract, ovum transportation and phenomena involved in pregnancy and parturition, are believed to be associated and affected by the motility of the female genital tract. It is therefore clear that in order to have a better understanding, hence subsequent control of these factors, a more detailed knowledge of the nature of spontaneous and hormone-induced patterns of genital tract motility is essential.

Megaloblastic anemia is no longer regarded as an uncommon complication of childbearing. A keen interest in this disorder has developed due to reports of increased incidence in the last decade (Giles and Shuttleworth, 1958; Ainley, 1961). Research has shown that most patients with megaloblastic bone marrow changes have either a low serum concentration of vitamin B12 or a low serum folate(1) activity, or both, which appear to be reasonably well correlated with the megaloblastic bone marrow changes (Lowenstein et al., 1962). [...]

The sport of show jumping (SJ) places great physical demands on the equine athlete. Despite this, selection and training strategies for the equine jumping athlete are largely based on anecdotal methods. SJ horses are generally selected at a young age based on quality of movement and jump technique. Numerous studies have provided information on the biomechanical demands of jumping. However, research has not sufficiently investigated how quality jump technique and performance may be improved through training in the SJ horse. The horse’s ability to execute the physical demands required for SJ is greatly influenced by muscular adaptation to training. Scientifically evidenced training programmes incorporate exercises, which mimic the duration, intensity, neuromuscular activity and movement patterns that are experienced during competition. However, a lack of understanding on how equine muscles facilitate the jumping effort represents a major gap in knowledge. Therefore, the aim of this thesis was to explore muscle firing patterns, which facilitate “quality” movement during different phases of the equine jump and to determine whether these support traditional training methods in the jumping horse. Surface electromyography (sEMG) and three-dimensional (3D) kinematic data were collected synchronously from a group of elite and non-elite jumping horses during canter and jump trials over a 1.0m fence. sEMG data were collected from the Superficial Gluteal, Biceps Femoris (vertebral head), Triceps Brachii (long head), Trapezius (cervical head), and Splenius. Lack of standardised methods within equine sEMG research represents a major gap in knowledge. Therefore, four original studies were conducted to develop optimal methods for the acquisition and analysis of sEMG data collected from equine subjects during jumping. These methods were employed in the main study of the thesis. An original questionnaire was designed to define “quality” movement and “traditional” training methods in the jumping horse, based on the opinions and preferences of highly qualified equestrians. Questionnaire results revealed obvious preferences for specific movement traits, which were used to inform kinematic data analysis. The incorporation of questionnaire findings ensured that research had practical application within the equine industry. Kinematic data analysis in the main study of the thesis revealed that “quality” movement traits between elite and non-elite athletes were largely non-significant. These findings suggested that movement alone may not be an accurate method for differentiating between good and poor jump technique and performance. However, sEMG data revealed differences in neuromuscular strategies between groups, which had a direct influence on jump technique. Elite horses exhibited the greatest capacity for generation of muscular force and power, particularly in the hindlimb during jump take-off. This finding was evidenced by greater: integrated EMG (iEMG), average rectified value, and peak amplitude data. As a result, “quality” jump technique was facilitated through greater vertical displacement and velocity of the centre of mass (CM) during jump take-off and suspension phases. These findings provide objective evidence for equestrians to place greater emphasis on strength (anaerobic training), as questionnaire findings revealed a trend for largely aerobic training programmes in the jumping horse. Findings also suggest that equestrians prioritise movement traits, which are indicative of muscular strength when selecting equine jumping athletes. This study has demonstrated the benefits of sEMG for the development of scientifically evidenced training and selection processes in the equine SJ athlete.

The hoof wall is adapted to take most of the weight-bearing of the foot and is anisotropic and homogeneous. Foals appear to be born with symmetrical paired feet which by maturity are frequently unequal in angle and width. They stand within minutes of birth subjecting the hoof wall to loading. Hoof growth rate and hoof compression may be factors affecting hoof shape. The effect of conformation changes during maturation upon loading and differential hoof growth was unknown. The aims were to; quantify and evaluate the epidermal structure, hoof growth rate, hoof renewal, dorsal hoof wall angle, plastic hoof compression, and hoof loading, during paediatric development. Hoof growth rate, renewal, and hoof angle were recorded in foals (n=80) and weanlings/yearlings (n=12) and the hoof wall structure of histological samples of fetuses and paediatric foals (n=15) was determined. Solar loading, hoof growth, and hoof angle was recorded in healthy foals (n=18) and compared to a group with acquired flexural deformity (n=9). Horn tubule size and number increased significantly, and density decreased significantly during maturation. The dorsal hoof wall angle declined with age. Hoof renewal in newborn foals was 145±15 days whereas weaning/yearlings were 283±26 days. A relationship between plastic hoof compression and time was found (r = 0.46, P = 0.002). Hoof compression in foals was 0.039±0.022mm per day and in weanling/yearlings 0.03±0.016mm per day. Hoof growth rate, hoof compression, and dorsal hoof wall angle, all correlated to ageing and differed between the healthy and acquired flexural deformity foals. The original findings in this thesis give a broad understanding of the developing equine hoof wall. Knowledge of renewal times allows predictions of healing in cases of partial hoof wall avulsion. Original data recording the structure of the developing hoof wall may lead to a greater understanding of its response to loading, while improved recognition of the angles of the digit and hoof during maturation will allow a more accurate assessment of conformation. Hoof distortion is affected by loading, hoof compression and hoof growth and comprehending the link between these factors may lead to enhanced treatment strategies for all ages of horse.

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