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Item Neurobiological impacts of kiwifruit consumption in a pig model and its effects on sleep and mood in young adults : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Sciences at Massey University, Palmerston North, New Zealand(Massey University, 2024) Kanon, Alexander PutraKiwifruit (KF) positively impacts gut health, specifically in alleviating gastrointestinal symptoms and improving laxation. Emerging evidence also suggests that consuming KF influences sleep and mood, with most studies indicating improvements in subjective measures of these attributes. Previous research has explored the mechanisms behind these effects using in vitro and rodent models, which have considerable differences to human physiology. This study explores the impact of New Zealand KF on various brain physiological aspects in animal models and humans. It explores the antioxidant neuroprotective potential of KF, examines alterations in the gut microbiome composition and bioamine concentrations, analyses temporal bioamine concentration effects in plasma and brain regions, and assesses the acute effects on human sleep quality and mood. Findings reveal that in one week, consumption of both green and gold KF reduced oxidative potential in plasma, increased concentrations of 5-Hydroxyindoleacetic Acid (5HIAA, a serotonin metabolite), and induced changes in the abundance of specific microbial genera along the colon of adult pigs, a more representative model of human physiology. Furthermore, green KF enhances antioxidant protective potential in plasma and various brain regions, while gold KF elevates plasma vitamin C levels and tends to reduce acetylcholinesterase activity across the entire brain. Temporal effects highlight distinct patterns in metabolite concentrations between green and gold KF, with γ-Aminobutyric Acid (GABA) and serotonin exhibiting notable interactions in different brain regions. Good and poor sleepers consuming KF before sleep had improved sleep quality and mood. Fresh KF facilitates easier sleep onset for good sleepers, while freeze-dried KF leads to increased ease of awakening in the morning for poor sleepers. Notably, both forms of KF increase the urinary excretion of 5HIAA and reduce feelings of sleepiness while increasing alertness. The inclusion of the fruit skin appears to increase improvements in sleep quality, suggesting a more noticeable effect. These studies provide valuable insights into the neurobiological effects of KF and support its potential as a functional food to improve sleep in humans.Item Spatiotemporal mapping of spontaneous smooth muscle motility in capacious organs: the ex vivo urinary bladder and in vivo gravid uterus of the rabbit: a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand(Massey University, 2023-08-20) Hulls, CorrinThe temporal and spatial dynamics of propagating myogenic contractions in the wall of the resting ex vivo urinary bladder and in vivo gravid uterus of the rabbit were characterised by spatiotemporal maps of area strain rate, of linear strain rate and contractile patch analysis, and related to cyclic variation in intravesical pressure (pves) in the bladder, and electrophysiological recordings in the gravid uterus. In the urinary bladder, patches of propagating contractions (PPCs) enlarged and involuted with a frequency in near synchrony with peaks in intravesical pressure. Maximum area percentage of the anterior surface of the bladder undergoing contraction and the sizes of individual PPCs also coincided with the peak in pves. Moreover, pves varied cyclically with total area of contraction and with the indices of the size and aggregation of PPCs, indicating that PPCs grew and involuted by a combination of peripheral enlargement or shrinkage and by coalescence or fission with other PPCs, their areas being maximal at or around the peak in pves. Bladder PPCs originated and propagated within temporary patch domains (TPDs) and comprised groups of near synchronous cyclic individual contractions (PICs). The TPDs were located principally along the vertical axis of the anterior surface of the bladder, either to the left or the right of midline and changed in location from one side to side and from side to tip or base. The sites of origin of PICs within PPCs were inconsistent, consecutive contractions often propagating in opposite directions along linear maps of strain rate. Similar patterns of movement of PPCs within TPDs of the same form occurred in areas of the anterior bladder wall that had been stripped of mucosa. The synchronisation and extended propagation of PICs within PPCs and the concurrent variation in pves of the bladder were sometimes lost or diminished, uncoordinated PICs then occurred, propagated shorter distances, and had little effect on pves. There was no evidence that any influence of bladder shape on stress influenced the principal direction of propagation of either PCCs or PICs or the disposition of TPDs. The disposition and dynamics of PPCs and their component individual myogenic contractions in the wall of the resting ex vivo tetrodotoxinized urinary bladder of the rabbit were characterised by spatiotemporal maps and related to cyclic variation in pves before and after the administration of carbachol, isoprenaline, carbenoxolone, and the RhoA-inhibitor Y-27632. The results confirm that the bladder wall can exhibit two contractile states that are of similar frequencies to those of the two types of electrophysiological discharge described by previous workers. In the first of these, large low frequency cyclic PPCs predominate. In the second, small irregular, higher frequency PICs predominate. Comparison of the effects of the drugs on the timing and disposition of contraction suggested indicated that the local spatial spread of contractions in PPCs was governed largely by myocytes, whilst the propagation, frequency, and duration of PPCs was likely governed via gap junctions between interstitial cells of cajal- intermuscular (ICC-IM) and myocytes. Spontaneous and oxytocin-induced contractile activity was quantified in the bicornuate uteri of pregnant rabbits maintained in situ, using data from electrophysiological recordings and spatiotemporal maps, and compared statistically. Spontaneous contractions occurred over a range of frequencies in gravid animals at 18-21 and at 28 days of gestation and propagated both radially and longitudinally over the uterine wall overlying each foetus. Patches of contractions were randomly distributed over the entire surface of the cornua and were pleomorphic in shape. No spatial coordination was evident between longitudinal and circular muscle layers nor temporal coordination that could indicate the activity of a localised pacemaker. The density and duration of contractions decreased, and their frequency increased with the length of gestation in the non-labouring uterus. Increasing intravenous doses of oxytocin had no effect on the mean frequencies, or the mean durations of contractions in rabbits of 18-21 days gestation but caused frequencies to decrease and durations to increase in rabbits of 28 days gestation, from greater spatial and temporal clustering of individual contractions. This was accompanied by an increase in the distance of propagation, the mean size of the patches of contraction, the area of the largest patch of contraction and the overall density of patches. Together these results suggest that progressive smooth muscle hypertrophy and displacement with increasing gestation is accompanied by a decrease in smooth muscle connectivity causing an increase in wall compliance and that oxytocin restores connectivity and decreases compliance, promoting volumetric expulsion rather than direct propulsion of the foetus by peristalsis. The latter effects were reversed by the β2 adrenergic receptor agonist salbutamol thus reducing area of contraction, duration, and distance of propagation. The characteristics of smooth muscle contraction that are associated with the maintenance of tone during accommodation appear to be to be similar in the capacious organs discussed. Hence, it appears there is patchy rather than uniform local revision of the state of tonal contraction over the surfaces of the various capacious organs during accommodation that can undergo neural modulation. There appears to be less similarity in regard to the mechanisms that secure the voiding contractions in these capacious structures. Whilst the actuation of the necessary shorter term increase in tone may be ultimately dependent upon a mechanosensitive myogenic reflex, the relative contributions of autonomic, hormonal, mechanical and voluntary reflexes that reset the threshold of this reflex and aid in the relatively rapid expulsion of the contents, appear to vary between organs.Item Genetic and phenotypic aspects of live weight, body condition score and reproductive success of beef cows in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Manawatū, New Zealand(Massey University, 2023) Weik, FranziskaThe productivity of spring-calving beef cows under New Zealand hill country conditions is dictated by the seasonality of the system. With the calf being the primary production output, reproductive success of the cow, alongside growth and carcass merit of the calves, is essential. The objective of this thesis was to quantify live weight (LWT), body condition score (BCS) and reproductive performance of beef breeding cows in New Zealand’s pastoral farming systems, both on a genetic and phenotypic level. This information was used to compare the profitability of cows that differ in their mature live weight (MWT) and other correlated traits exposed to variable feed availability. The BCS of cows is a relevant indicator trait for productivity of the maternal herd on a phenotypic level. Cows in good body condition, particularly in the period leading up to mating, are more likely (P < 0.001) to get pregnant. The curvilinear relationship indicates that most improvement may be obtained by reducing the percentage of low conditioned cows in the herd (75.7% pregnancy rate at BCS 4.5 versus 93.3% pregnancy rate at BCS 8). From a genetic perspective, the correlation between BCS and pregnancy rate was low (rg = -0.10). Pregnancy rate was considered as a separate trait for each of 15-month-old heifers, first-lactation 2-year-old cows and mature cows. Genetic variation and heritability were low for 15-month-old heifers and mature cows (h2 ≤ 0.06), but greater for 2-year-old cows (h2 = 0.12-0.14), indicating that 2-year-old cows offered the greatest potential for selection on pregnancy rate. At all ages, heritabilities were greater for BCS (h2 = 0.26) and for MWT (h2 = 0.48) than for pregnancy rate. Placing downward pressure on MWT may decrease the ability of cows to reach BCS targets (rg = 0.24) which can impact on subsequent reproductive success. Most growth and weight traits in finishing cattle had only limited genetic correlations with rebreeding ability of female herd replacements (rg = 0.11–0.32) or cow BCS (rg = 0.12–0.36) but high genetic correlations were observed with MWT (rg = 0.45–0.92) in the current study. Fat and muscle traits recorded on finishing animals were negatively genetically correlated with MWT (rg = -0.40 - -0.19) but were only weakly correlated with cow BCS (rg = 0.02–0.25). Comparison of simulated cows selected on the basis of MWT estimated breeding values (EBV) from within the current New Zealand Angus population indicated that there was little variation in profitability among different cow MWT types under conditions where supplementary feed in terms of increased pasture allowance was introduced to prevent excessive loss of condition. The cow MWT types in the simulation model differed in MWT EBV and correlated traits such as calf size, and adjustments in stocking rate were made to reflect changes in feed requirements per cow. Overall, this thesis provided evidence that for cow-calf production systems where the primary focus is on enhancing the maternal performance of the cow, selection emphasis should be on improving rebreeding ability of 2-year-old cows as the most heritable reproduction trait, and on BCS of cows. Within the limitations of this study, cow types that differed in their MWT had only minor differences in profitability when simulated under a variable feed supply, such that selection strategies may lean towards prioritising the performance of finishing animals while taking advantage of those larger calves from bigger cows and accepting a correlated increase in MWT. This information can be used to develop guidelines for future genetic evaluation programs for beef cattle in New Zealand.Item Physiological demands of jockeys in relation to injury risk, performance, and career longevity : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at School of Veterinary Sciences, Massey University, Manawatu, Aotearoa, New Zealand(Massey University, 2022) Legg, KylieJockeys work at close to their physiological capacity during a race. However, despite the pivotal role of the jockey in the success of racing, there are limited data published on the physiological challenges of race riding and the influence of muscular fatigue on the jockeys during a race and over their careers. Until the sport-specific physiological demands of race riding are quantified, the development of evidence-based sport specific and potentially performance enhancing jockey training programmes cannot be realised. Successful training interventions require knowledge of the physiological demands and performance characteristics of the specific sport. Therefore, the aims of this thesis were to characterise the injury risk, performance and career longevity of jockeys in relation to their overall and specific, training and competition level physiological demands. Using race-day records of 786 jockeys riding over 14 years (2005 – 2019) of Thoroughbred racing in New Zealand (n = 421,596 starts), descriptive statistics, uni- and multi- variable analyses and Kaplan Meier survival curves, it was determined that jockeys with higher competitive workloads performed better, had fewer falls and longer careers than those with lower competitive workloads. A nationwide online survey completed by 40% of the jockey population in New Zealand identified that the main form of exercise for jockeys was riding in training and racing. This indicated that jockeys with higher competitive workloads may have a greater degree of sport specific fitness from regular competitive riding that jockeys with lower workloads (or apprentice jockeys beginning their career) are unable to gain through simply riding track-work and trial rides. The ride specific physiological demands, body displacements and muscle activities of jockeys were determined by instrumenting jockeys with heart rate (HR) monitors, global positioning system (GPS), accelerometers (body displacement) and electromyographic clothing (recording eight muscle groups: quadriceps, hamstrings, gluteal, lower back, obliques, abdominal, trapezial and pectoral) during a typical day at track-work, trials, and races. The physiological (aerobic) demands of riding increased from low during track-work, to moderate when riding trials, and near-maximal during race-riding. Race-riding jockeys adopted a lower crouched posture with greater hamstring activation than jockeys riding track-work or trials. These studies provide evidence that jockeys need more specificity in training for competitive race-riding. Future studies could use these data to model the optimum level of competition specific fitness for a jockey to maintain to both reduce injury risk and optimise performance, which would in turn, enhance the career longevity of jockeys.Item Factors influencing the exertional heat stress response in athletic females : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy, School of Sport, Exercise and Nutrition, Massey University, Palmerston North, New Zealand(Massey University, 2022) Zheng, HuixinClimate change continues to expose an increasing proportion of the global population to more frequent extreme heat events. Concurrently, our society has seen an increase in the number of women that participate in physically demanding leisure time (exercise and sport) and occupational activity. Yet, limited research has been conducted to understand the female physiological responses to exercise-heat stress, especially when considering their various ovarian hormone profiles. This thesis expands our understanding of the female physiological responses to heat stress from different perspectives. Firstly, previous evidence has demonstrated that ambient heat stress amplifies the increase in the cytokine interleukin-6 following exercise, an up-regulator of hepcidin - the hormone that downregulates iron metabolism. In Chapter Five iron sufficient females’ serum iron parameters and hepcidin levels following a self-paced cycling work trial were compared in temperate and hot conditions, and different menstrual phases. IL-6 and hepcidin both increased post-exercise (198% and 38%, respectively), interestingly, neither were affected by ambient temperature or menstrual phase (all p>0.15). Chapter Six determined the measurement error of a 30-min self-paced cycling protocol in moderate, warm-dry and warm-humid environments using thirty-three athletic women distinguished by their ovulatory status and ovarian hormone concentrations. With an ICC=0.90, p<0.01, and a mean CV of 4.7%, SEM of 3.8 kJ (2.1 W) and reliable bias of -2.1 kJ (-1.2 W), it was confirmed that this protocol has high test-retest reproducibility that is not influenced by ambient environment or a female’s hormonal/ovulatory status. Finally, in order to better predict females’ risk for exertional heat stress, Chapter Seven attempted to clarify the role of the ovarian hormones when explaining the variance of the core temperature response using the 30-min self-paced cycling protocol from Chapter Six in thirty-six trained women. It was found that estrogen contributes minimally, whilst baseline core temperature and power output contribute the most to peak core temperature during exercise. Taken together, this thesis deepens our understanding of females’ physiological responses and testing norms for current sport science practices. Specifically, it details iron metabolism responses when exposed to exercise-heat stress, elucidates the role of ovarian hormones regarding exertional heat strain and adds test-retest norms specific to athletic women to the available literature.Item A study of a strain of albino mice with regard to suitabilty for investigations of the role of the adrenal cortex in mammary gland growth : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in the University of New Zealand(Massey University, 1956) Munford, R EThe experiments reported in this thesis were carried out in the hope that they might assist in the clarification of the role of the endocrine system in the regulation of mammary gland development. A large part of the work was concerned with the elucidation of the general effects of adrenal insufficiency in mice, and with the maintenance of adrenalectomised mice by the injection of cortisol acetate. It is hoped that the results obtained with these mice will be of some assistance in future studies of the endocrine control of the growth of the mammary glands in mice, where it is dersired to exclude any influence mediated by, or originating from the animal's own adrenal cortex. This study w_as prompted by Dr. D.S. Flux, to whom the author is indebted for guidance, encouragement, and patient instruction. The advice of Professor I.L. Campbell, in whose department the work was carried out, and the assistance of Mr D.J. Myers are gratefully acknowledged. The author also wishes to thank the staff of the College Library for their considerable efforts in obtaining a large number of .journals on loan from other institutions, and Mr. K.A. Rose for his work in connection with the reproduction of the illustrations. Thanks are also due to the following for gifts of material to Dr. D.S. Flux: Organon Ltd., England for oestrone (through the courtesy of Mr. G.B. Davis of The Dental and Medical Supply Co. Ltd.) A.M. Satterthwaite and Co. Ltd. for cortisol (through the courtesy of Mr. F.A. Hacking). [From Preface]Item Skin thickness as a potential indirect trait for genetic improvement of lamb survival : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand(Massey University, 2021) Soltanighombavani, MasoudLamb survival, as a trait of great economic importance with low heritability, might show more response to indirect selection for traits of higher heritability that are genetically correlated with lamb survival, as a trait of high economic importance. The main objective of this thesis was to explore if ultrasonographically measured skin thickness (ST) at about nine months of age could be considered as an alternative to direct selection for lamb survival from birth to weaning (SBW). For this purpose, in the first step, the reliability of ultrasonography as an accurate and noninvasive method for measurement of ST was validated using plicometry and histometry. In the second experiment, the heritability of ultrasonographically measured ST at an age of about 9 months was estimated to be 0.21 ± 0.03 and 0.20 ± 0.03, respectively from analyses with and without adjustment for live weight at scanning (LWS), implying that the trait would respond to genetic selection. Estimates of genetic correlation of ST with SBW from the analyses with LWS considered as a covariate for ST ranged from 0.16 to 0.35 depending on the minimum number of progeny per sire for each trait, while the corresponding estimates from the analyses with LWS excluded ranged from 0.08 to 0.27. When correction was made for LWS, ST showed genetic correlations of 0.21 ± 0.07, -0.13 ± 0.09, -0.32 ± 0.12, -0.23 ± 0.09, -0.10 ± 0.10, 0.02 ± 0.11, and 0.20 ± 0.11 with fat depth (FD), eye muscle depth (EMD), weights at weaning (WWT), 8 months (LW8), scanning (LWS), and 12 months (LW12), and fleece weight at 12 months (FW12), respectively. The corresponding estimates when no adjustment was made for LWS, were respectively 0.24 ± 0.08, -0.08 ± 0.10, -0.01 ± 0.12, 0.09 ± 0.09, 0.19 ± 0.09, 0.30 ± 0.10, and 0.20 ± 0.11. In the third experiment, the role of skin thickness in thermoregulation through its effect on surface heat loss and a few other indices of cold resistance was explored in two groups of new-born lambs with the thickest skin (thick-skinned category) and the thinnest skin (thin-skinned category) exposed to cold-stress. As a result of lower skin surface temperature (as an indicator of heat loss) in thick-skinned lambs compared to thin-skinned lambs, the first group had higher rectal temperature and were more likely to maintain body temperature during cold stress, even though they produced significantly less heat (W Kg-1). This means there is less need to consume body reserves as a source of energy and consequently better conservation of body reserves in the thick-skinned lambs. In the fourth experiment, skin thickness measured at six to eight months of age was revealed to be a moderately reliable indicator of skin thickness at birth. This is of high importance from both practical and economic points of views. Measuring skin thickness at six to eight months of age is much easier than at birth for sheep farmers/breeders. Furthermore, ultrasound measurement of skin thickness at these ages facilitates simultaneous recording of other traits of importance like fat depth and eye muscle depth, which are normally taken at these ages. In the final study, the effects of genetic variation in the uncoupling protein 1 (UCP1), prolactin (PRL), and prolactin receptor (PRLR) genes on the indices of cold resistance were tested in new-born lambs exposed to cold stress. Although significant effects on some of the indices were observed at/during some time-points/periods of the cold stress, they seem to be mostly due to biases resulting from low number of lambs rather than being real. Considering all the findings, it could be generally concluded that ultrasonographically measured skin thickness at about nine months of age could be considered as a supplement to direct selection for lamb survival in genetic improvement programs. Nevertheless, the large standard errors of the correlations of ST with SBW as well as the unfavorable correlation of ST with other traits should also be considered.Item Injury incidence and physiological requirements of a domestic amateur women's rugby union team in New Zealand : a thesis submitted to Massey University in fulfilment of the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand(Massey University, 2021) King, DouglasWomen’s rugby union has undergone a period of transition to become, reportedly, the fastest growing form of the game worldwide. Although the game is played nationally and internationally, it was not until 1991 that the first Rugby World Cup for women (RWC(W)) was held. Despite increased popularity and growth, the published studies investigating the epidemiological aspects of match and training in women’s rugby union is limited. Of the published studies to date, none have reported on aspects related to women’s rugby union participants in New Zealand. Therefore, the overall aim of this thesis was to explore and document the epidemiology of injuries in an amateur women’s rugby union team in New Zealand. As fatigue has been indicated as a possible injury risk factor, the physiological demands of match participation in amateur women’s rugby union were also assessed. Specific aims of the thesis were (1) The identification of the physiological and heart-rate demands of match participation for amateur women rugby union players; (2) The identification of the most common site, type, severity, and frequency of injuries that occur to women in rugby union training and match related activities (Systematic Review); (3) The identification of the most common site, type, severity, and frequency of injuries that occur to women in rugby union training and match related activities in New Zealand. The methodological approaches utilised in this thesis included an epidemiological analysis (Chapter 3), and a prospective observational cohort analysis (Chapters 2, 4 and 5). In measuring the movement demands of amateur domestic women’s rugby union (Chapter 2), player movements were monitored using microtechnology GPS devices. Players’ heart rates were also continuously monitored during match participation using a portable monitor. A mean total distance per match of 3,546.6 ±1,329.2 m was recorded over 28 matches. This resulted in a mean distance of 38.3 ±13.7 m.min-1 which was less than women’s football (79.3 to 118.0 m.min-1: mean 101.0 ±11.9 m.min-1), hockey (79.0 to 115.0 m.min-1: mean: 98.5 ±15.6 m.min-1) and women’s elite rugby union (54.8 to 68.0 m.min-1; mean: 61.4 ±9.3 m.min-1). Although Forwards recorded a lower total distance (3,409.7 ±1,201.9 m vs. 3,692.3 ±1,440.5 m) and m.min-1 (36.7 ±12.4 m.min-1 vs. 40.0 ±14.9 m.min-1) than Backs, they had a similar player-load (PL) (3.8 ±1.3 au.min-1 vs. 3.9 ±1.4 au.min-1), PL 2-dimensional (2.9 ±1.0 au.min-1 vs. 2.9 ±1.1 au.min-1), PL Forward (1.8 ±0.7 au.min-1 vs. 1.7 ±0.7 au.min-1), PL side (1.9 ±0.7 au.min-1 vs. 1.9 ±0.7 au.min-1) and PL vertical (2.9 ±1.0 au.min-1 vs. 3.0 ±1.2 au.min-1) when compared to Backs. Forwards recorded a higher maximum heart rate than Backs (191 b.min-1 vs. 188 b.min-1), indicating a higher cardiovascular stress and physiological strain for Forwards compared with Backs. The results of this study suggested that the physical and physiological profile of the playing group, at the amateur domestic level of women’s rugby union, were quite similar and may be suggestive of generalised, rather than specialised, training regimes that fail to prepare players for the position specific demands needed at higher levels of competition. The systematic review (Chapter 3) of literature reporting on women’s rugby union incorporated both rugby-15 and rugby-7s match and training related published studies. Only 10 articles identified through systematic searches of PubMed, SPORTDiscus, Web of Science Core Collection, Scopus, CINAHL(EBSCO) and ScienceDirect databases using keywords were included in the review. The incidence of injuries in rugby-15s varied from 3.6 (95% CI: 2.5-5.3) per 1,000 match-hr (including training and games) to 37.5 (95% CI: 26.5-48.5) per 1,000 match-hr, with a pooled incidence of 19.6 (95% CI: 17.7-21.7) per 1,000 match-hr. For rugby-7s, the injury incidence varied from 46.3 (95% CI: 38.7-55.4) per 1,000 match-hr to 95.4 (95% CI: 79.9-113.9) per 1,000 match-hr with a pooled incidence of 62.5 (95% CI: 54.7-70.4) per 1,000 player-hr. The tackle was the most commonly reported injury cause, with the ball carrier recording more injuries than the tackler at the collegiate, and RWC(W) levels of participation. Concussions and sprains/strains were the most commonly reported injuries at the collegiate level of participation. The incidence of injury in women’s rugby-15s and rugby-7s was lower than in men’s professional rugby-15s and rugby-7s competitions, but similar to male youth rugby-15s players. Differences in reporting methodologies limited comparisons of results between studies. Of note, the systematic review failed to identify any New Zealand based studies in women’s rugby union. A key finding of the systematic review was that there were no women’s rugby union training-specific studies identified. By conducting a prospective cohort observational study on the training sessions of an amateur women’s rugby union team, over two-years (Chapter 4), it was identified that the total injury incidence was 11.4 (95% CI: 8.3 to 15.6) per 1,000 training hrs. There were 12 injuries that resulted in a time-loss injury incidence of 3.6 (95% CI: 2.0 to 6.3) per 1,000 training-hrs. The tackle was the most common cause for total (3.0 [95% CI: 1.6 to 5.6] per 1,000 training-hrs.) injuries, but collisions (1.5 [95% CI: 0.6 to 3.6] per 1,000 training-hrs.) with the ground or another person were the most common cause for time-loss injuries. The training injuries occurred most often to the lower limb and during the latter part of training sessions. These injuries were mostly minor in nature, resulting in minimal time-loss away from training. The time-loss injury incidence (3.6 [95% CI: 2.0 to 6.3] per 1,000 training-hrs.) for the amateur women’s rugby 15s team players was higher than that reported for National (1.2 [95% CI: 0.4 to 3.1] per 1,000 training-hrs.) and RWC(W) (0.2 [95% CI: 0.0 to 2.2] to 3.0 [95% CI: 1.8 to 5.0] per 1,000 training-hrs.) competitions. The incidence of match injuries (Chapter 5) was conducted utilising a prospective cohort observational study on an amateur women’s rugby union, over two consecutive seasons. A total of 138 injuries were recorded resulting in an injury incidence of 247.0 (95% CI: 209.1 to 291.9) per 1,000 match-hrs. A total of 57 injuries resulted in a time-loss injury incidence of 102.0 (95% CI: 78.7 to 132.3) per 1,000 match-hrs. Although Forwards (261.8 [95% CI: 209.7 to 326.9] per 1,000 match-hrs.) recorded a higher total injury incidence than Backs (230.2 [95% CI: 178.7 to 296.4] per 1,000 match-hrs.), Backs recorded higher time-loss injury incidence (107.4 [95% CI: 74.2 to 155.6] per 1,000 match-hrs.) than Forwards (97.3 [95% CI: 67.6 to 140.1] per 1,000 match hrs). The lower limb sustained the highest injury incidence, with the knee having the greatest proportion of these injuries for both total (48.3 [95% CI: 33.1 to 70.5] per 1,000 match-hrs.) and time-loss (21.5 [95% CI: 12.2 to 37.8] per 1,000 match-hrs.) injuries. Sprains and strains recorded the highest incidence of all the injuries recorded and the lower limb body region recorded the most days lost and had the highest mean days lost per injury. The incidence of concussion (16.1 [95% CI: 8.4 to 31.0] per 1,000 match-hrs.) over the study was higher than previous studies reporting on women’s rugby union at the RWC(W) (3.5 [95% CI: 1.7 to 7.0] per 1,000 match hrs) and collegiate rugby union (1.6 [95% CI: 1.1 to 2.3] per 1,000 player match-hrs.) levels of participation. The tackle was recorded as being the most common injury cause and this was expected. Upon further analysis, it was identified that the action of being the ball carrier, rather than the tackler, during a tackle situation was associated with a notably higher injury incidence than any other match event. Future research is warranted to identify risk factors involved in the tackle unique to women participants. This PhD thesis has contributed knowledge regarding the incidence of injuries in amateur women rugby union players in New Zealand which has not been undertaken before. In addition, this PhD thesis has contributed further knowledge regarding the physiological demands of amateur women’s rugby union match participation (see Chapter 6).Item Effect of processing on muscle structure and protein digestibility in vitro : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand(Massey University, 2021) Chian, Feng MingThe objective of this thesis was to investigate the effect of processing on meat protein properties, muscle structure and in vitro protein digestibility of beef. Meat processing techniques including pulsed electric field (PEF), shockwave (SW) processing, exogenous enzyme (actinidin) treatment, and sous vide (SV) cooking were explored, either alone or in combination, in this project. This thesis also aimed to study the diffusion of enzymes (actinidin from kiwifruit and pepsin in the gastric juice) into the meat. The first experiment investigated the effect of PEF processing alone on the ultrastructure and in vitro protein digestibility of bovine Longissimus thoracis, a tender meat cut (Chapter 3). It was observed that the moisture content of the PEF-treated samples (specific energy of 48 ± 5 kJ/kg and 178 ± 11 kJ/kg) was significantly lower (p < 0.05) by 1.3 to 4.6 %, compared to the untreated samples. The pH, colour, and protein thermal profile of the PEF-treated muscles remained unchanged. Pulsed electric field treatment caused the weakening of the Z-disk and I-band junctions and sarcomere elongation (25 to 38 % longer) of the muscles. The treatment improved in vitro meat protein digestibility by at least 18 %. In this thesis, the protein digestibility was determined in terms of the ninhydrin-reactive amino nitrogen released during simulated oral-gastro-small intestinal digestion. An enhanced proteolysis of the PEF-treated meat proteins (such as α-actinin and β-actinin subunit) during simulated digestion was also observed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The improvement in protein digestibility of the PEF-treated meat was supported by more severe disruption of Z-disks and I-bands observed in PEF-treated samples, at the end of simulated digestion. In the second experiment, PEF treatment (specific energy of 99 ± 5 kJ/kg) was applied to bovine Deep and Superficial pectoral muscles in conjunction with SV cooking (60 ℃ for 24 h) (Chapter 4). This muscle cut was tested as it is a tough cut and requires slow cooking. There was no significant difference detected in the specific activities of the sarcoplasmic cathepsins present in the cytosol between the control and PEF-treated samples, both before and after cooking. In addition, similar micro- and ultrastructures were observed between the control SV-cooked and PEF-treated SV-cooked pectoral muscles. The combined PEF-SV treatment increased the in vitro protein digestibility of the pectoral muscles by approximately 29 %. An improvement in proteolysis of the treated meat proteins (e.g. myosin heavy chains and C-protein) during simulated digestion was also observed using SDS-PAGE. More damaged muscle micro- and ultrastructures were detected in PEF-treated SV-cooked muscles at the end of in vitro oral-gastro-small intestinal digestion, showing its enhanced proteolysis compared to the control cooked meat. Next, the effect of SW processing and subsequent SV cooking on meat protein properties, muscle structure and in vitro protein digestibility of bovine Deep and Superficial pectoral muscles were investigated (Chapter 5 and 6). Shockwave processing (11 kJ/pulse) alone decreased the enthalpy and thermal denaturation temperature of the collagen (p < 0.05) when compared to the raw control, studied using a differential scanning calorimeter. The purge loss, pH, colour, and the protein gel electrophoresis profile of the SW-treated raw muscles remained unaffected. Shockwave processing led to the disorganisation of the sarcomere structure and also modified the protein secondary structure of the myofibres. After subsequent SV cooking (60 ℃ for 12 h), more severe muscle fibre coagulation and denaturation were observed in the SW-treated cooked meat compared to the cooked control. An increase in cook loss and a decrease in the Warner-Bratzler shear force were detected in the SW-treated SV-cooked meat compared to the control cooked meat (p < 0.05). The in vitro protein digestibility of the SW-treated SV-cooked meat was improved by approximately 22 %, with an enhanced proteolysis observed via SDS-PAGE, compared to the control SV-cooked meat. These results were supported by the observation of more destruction of the micro- and ultrastructures of SW-treated cooked muscles, observed at the end of the simulated digestion. The effect of the kiwifruit enzyme actinidin on muscle microstructure was studied using Picro-Sirius Red staining (Chapter 7). Meat samples were subjected to two different conditions, simulating meat marination (pH 5.6) and gastric digestion in humans (pH 3). Actinidin was found to have a greater proteolytic effect on the myofibrillar proteins than the connective tissue under both conditions. When compared with pepsin under simulated gastric conditions, actinidin had a weaker proteolytic effect on the connective tissue of cooked meats. Nevertheless, incubating the cooked meat in a solution containing both actinidin and pepsin resulted in more severe muscle structure degradation, when compared to muscles incubated in a single enzyme system. Thus, the co-ingestion of kiwifruit and meat could promote protein digestion of meat in the stomach. In addition, both actinidin and pepsin were successfully located at the edges of the muscle cells and in the endomysium using immunohistofluorescence imaging. The observations suggest that the incubation solutions penetrate into the muscle through the extracellular matrix to the intracellular matrix, enabling the proteases to access their substrates. Overall, the present work demonstrated that there were strong interactions between processing, muscle protein properties and structure, and in vitro protein digestibility of the meat. Processing induces changes in meat protein properties and muscle structure, which in turn affects the digestion characteristics of muscle-based foods.Item The physiology of the keratin plug formation in the teat canal of dairy cattle and its interaction with current and novel methods for prevention of intramammary infections : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science, Massey University, Turitea, Palmerston North, New Zealand(Massey University, 2021) Notcovich, ShirliThe incidence of intramammary infections (IMI) in dairy cows in the early dry period is the highest of the lactation cycle when methods to prevent IMI are not applied. This high incidence is comparable only with that observed near calving. At the end of lactation, the teat is sealed by a plug formed mainly by keratinised cells, detritus and proteinaceous material. Research suggests that the keratin plug acts as a physicochemical barrier throughout the dry period that impedes the entrance of bacteria. However, the physiological mechanism of keratin plug formation is still uncertain. The main objectives of this thesis were to characterise the physiological functions of the teat canal (TC) during the early dry period and assess how they associate with the presence of IMI. A further objective was to evaluate the modes of action of a current mastitis preventative containing bismuth subnitrate and a novel formulation of micronized keratin that is under investigation as a teat seal for preventing IMI during the early dry period. To address these objectives a novel biopsy method was developed to allow investigation of the physiological characteristics of the epithelial tissues of the TC. A transcriptomic analysis of the TC epithelium after drying off showed that epithelial cells decreased expression of mitotic and immune-response related genes. A Streptococcus uberis strain was used in a challenge study aiming to examine mechanisms of colonization in the TC and the response of the epithelial tissue to progressing infection. This Streptococcus uberis challenge did not result in colonization of the TC nor in IMI with S. uberis. Nevertheless, a reduction in the thickness of the stratum granulosum and the keratin layer of the TC epithelium was observed. This coincided with an increase in TC colonization by non-pathogenic bacteria and a decline in the concentration of certain cytokines after drying off. These changes observed in the TC epithelium support previous reports showing increased incidence of IMI by non-pathogenic bacteria during the early dry period. Antimicrobial effects and neutrophil cell responses were evaluated in vitro in two studies to test previously hypothesised action mechanisms for bismuth subnitrate and a novel keratin-based internal teat sealant (ITS) formulation. Bismuth subnitrate showed an inhibitory effect on bacterial growth, contrary to the current description of ITS as non-pharmacological, inert physical barriers. No activation of a cellular response was observed for keratin or bismuth formulations in vitro. Bismuth subnitrate and keratin were also tested in vivo for their effect on the formation of the keratin plug. The hypothesis of this study was that these treatments induce expression of mitogenic genes that induce a faster sealing of the teat canal. There was no modification of gene expression after treating cows with bismuth subnitrate or the novel keratin-based ITS formulation during the formation of the natural keratin plug, and no modification of the closure status of the teat canal lumen, suggesting that neither of the two treatments induced an improved sealing of the teat canal after drying off through increased keratin production. These findings contribute to the knowledge of keratin plug formation and physiological characteristics of the TC during involution. They align with and partially explain some of the literature-reported events observed during the early dry period. The knowledge gained provides support for future product development aimed to increase protection of the mammary gland during the dry period.