The way we assess readiness for slaughter in beef cattle has not progressed in the past 200 years, with subjective visual and manual assessments of cattle still the primary mechanisms used to determine peak condition, resulting in less than half of all cattle carcases meeting a UK premium classification. Current losses to the UK Beef industry are estimated at approximately £12.5 million per year through the sending of over-fat and poorly conformed cattle to the abattoir. With global population rapidly increasing, there is a fundamental need to provide more food efficiently and effectively from the resources we have. Therefore, successfully reducing wastage and improving carcase quality across the UK beef industry through accurate assessment and selection of beef cattle for slaughter is an important step forwards towards a sustainable future for beef production. The EUROP system of bovine carcase classification dictates which carcases are most desired for the current market, with those failing to meet market specification subject to a penalty. The aim of this research project was therefore to provide farmers with an objective tool using a binary logistic regression model, to combine fat and morphometric measurements taken from live cattle, in order to help predict which cattle are most likely to achieve a desired carcase classification and therefore most suitable for slaughter. Through the use of a series of binary logistic regression models, it was discovered that out of 15 measurements taken from cattle, a combination of pelvis height, pelvis width, 10th and 12th rib fat point readings and the P8 fat point reading were best able to predict the likelihood of cattle meeting a UK premium carcase classification. In a later study, when breed was factored into the model on a larger, more commercial scale, this reduced the number of measurements required to just the pelvis width and 12th rib fat point reading, subsequently increasing the practicality to apply this research on-farm.

Broiler chicken has been bred for meat production and is characterised with a very fast skeletal muscle growth rate, whilst the layer type have been bred for the production of eggs. This study aimed to understand how intense breeding programmes have developed commercial meat type chickens that have resulted in a fast muscle growth phenotype by a comparative analysis of gene expression between fast-growing broiler and slow-growing layer type chicken. Two chicken trials were carried out. In Trial 1 from fast-growing broiler Ross 308 genotype (R) fast-growing breast Pectoralis major (RPM) and slow-growing leg Peroneus tertius (RPT) muscles were collected at day 14, 36 and 42 post-hatch. In Trial 2, from fast-growing broiler Ross 308 (R) or slow growing layer Hy-Line (H) Pectoralis major (either RPM or HPM) and Peroneus tertius (either RPT or HPM) were collected at day 4, 14, 23, 35 and 42 post-hatch. In Trial 1, there was a muscle type x age interaction in muscle weights with the RPM having the highest value at day 43 (P < 0.001). This effect was also reflected in the protein content with RPM having more protein than RPT. However, RPT had a higher DNA content per unit tissue weight (muscle type x age interaction, P=0.003) with highest value seen at day 43. This suggests that muscle cells of RPM are bigger than those in RPT and that as a result they contain more protein, potentially reflecting RPM hypertrophy compare to RPT. In Trial 1, genes associated with glycolysis, GAPDH and -enolase, were significantly higher in the faster growing RPM (P < 0.05). Genes involved in serine biosynthesis PHGDH, PSAT and PSPH, as well as P70S6K involved in protein translation, also had a significantly higher expression in the RPM when compared to the RPT (P < 0.05) indicating a greater rate of protein synthesis in the faster growing RPM. Expression of genes associated with smaller muscles (myostatin) or protein degradation (calpastatin, the specific endogenous inhibitor of calpain proteinases) were not different between muscles. LIM domain proteins, CSRP3 and FHL2, had a higher expression in the slower growing muscle, indicating the possibility of those two genes being negative regulators of muscle growth, or may be involved in the upregulation of muscle regenerative physiological processes, as a result of the strain on the leg muscles induced by physical activities during locomotion. In Trial 2 there was a three-way interaction between genotype, muscle type and age in muscle growth (P < 0.001) with the highest value seen at day 42 in the RPM. There was a 3-way interaction between genotype, muscle type and age in the expression of -enolase (P=0.036) with the highest value seen at day 42 in the HPM. For -Enolase mRNA expression, there was a separate genotype and a muscle type effect (both P < 0.001) with HPM and HPT been higher than RPM and RPT, and PM muscles having a higher expression than PT muscles in both genotypes. When the serine synthesis pathway was examined, there was a genotype x age interaction (P=0.046) for PSAT and PSPH gene expression, with the highest expression at day 35 in both muscles of the Ross 308 genotype for the former, whilst the latter had the highest expression in the RPM at day 35. For ASNS mRNA expression there were significant genotype (P=0.004) and muscle type effects (P=0.014), with the Ross 308 genotype having the higher expression and the PM being greater than PT. For P70S6K mRNA expression, PM was higher than PT (P=0.012). For P70S6K total protein there was a significant muscle type x age interaction (P=0.049), RPM and HPM being higher than RPT and HPT at days 14 and 35. For calpain activity only at day 35 was there significant genotype x isoform interaction (P < 0.001), with the Hy-Line genotype having a higher micro and milli calpain activity than the Ross 308 genotypes, irrespective of muscle. For trypsin, chymotrypsin and caspase – like activities of the proteasome, there was a significant genotype effects (P < 0.001). In all three assays Ross 308 muscles had a higher activity when compared muscles from Hy-Line at both time points. For the ubiquitin ligases there was a borderline muscle type x time interaction (P=0.05) in the expression of MAFbx mRNA, with the RPT and HPT having a higher expression than the RPM and HPM respectively at day 14. For MuRF1 mRNA there was a significant genotype x age interaction (P < 0.001) with the HPM and HPT having a higher expression than the RPM and RPT at day 14 and 35. For CSRP3 there was a genotype x age interaction (P < 0.001), with the highest expression seen in the HPT at day 42. There was also muscle type effect within genotypes with the RPT and HPT having a higher expression than the RPM and HPM (P < 0.001). Trial 2 indicated that there is an increase in protein synthesis which leads to clear increase in protein accretion in faster growing chicken muscles, thereby supporting the wealth of literature detailing protein turnover in chicken skeletal muscles. There also appears to be an interaction between protein synthesis and degradation, however in most cases protein synthesis seems to be more dynamic and these changes seem to appear around day 35. The novel findings of this study were the observed increase in the expression genes that could limit the synthetic capacity of non-essential amino acid (non-EEA) in fast growing muscles.

This thesis presents a sociological analysis of the organisation and significance of thoroughbred horse-racing in Britain. It focuses on both the internal world of racing and the relationship between racing and the wider society. It argues that such an approach is necessary for an appreciation of the full meaning of horse-racing as a social institution. The study finds two major points of articulation between racing and wider social processes: first in terms of the role of racing in elite sociability and structuration; and second in terms of its location in working class culture, particularly as it is mediated through the working class betting tradition. The precise linkages, continuities and changes within these areas are explored in order both to amplify and qualify the conventional observation of a coalescence of interests in racing between otherwise sharply differentiated social strata. The analysis points to the conclusion that while the symbolic legacy of this observation may be strong, the evidence for this symmetry and its pervasiveness is now more tenuous and its implications for the general process of class identification heavily circumscribed. The analysis of the discrete world of horse-racing concentrates first upon the social production of the racehorse as reflected through the position of the stable worker. Evidence is presented which both casts doubt on received images of this process and indicates some erosion of the distinctive cultural output of racing which has customarily attracted a benign curiosity in outsiders. Secondly, attention is focused on developments in the control and administration of racing. In particular, the emergent role of the state in this process is shown to have reverberated through both the production and regulatory sectors of the industry, provoking a profound dislocation in the exercise of power. Such intervention is also demonstrated to have reacted upon the production and consumption of betting, precisely the activity which provided the original rationale for intervention in racing. While there are important elements of continuity in the organisation of racing, the thesis expresses the view that racing has passed over a watershed in the last two decades which in time may prove to have eroded its distinctive contribution to British society.

Necrotic enteritis (NE) is an important enteric disease in poultry production that has re-emerged as a major problem following an EU wide ban on the use of in-feed antimicrobials. Although the primary aetiological agent of disease is Clostridium perfringens type A, a commensal in the gastrointestinal tract (GIT) of chickens, numerous additional influential factors have been reported that can predispose chickens to NE. These precipitating factors mainly include diet, co-infection with other pathogens particularly coccidia, as well as environmental and management factors. Despite being first described almost more than 50 years ago, a reliable, consistently reproducible experimental model for NE induction is still lacking. Here, a series of experiments were conducted to investigate the importance of the various potential predisposing factors, in isolation and in combination, that are believed to play a role in sub-clinical NE development: feed withdrawal, dietary protein sources, co- infection with coccidia, C. perfringens dose and contact with reused litter. In addition, chicken breed sensitivity to NE was assessed, and last, but not least, blood and gut tissue samples were used to identify novel biochemical markers for sub-clinical NE. Chapter 3 reports an experiment showing that feed withdrawal up to 24 hrs in experimentally challenged birds did not result in NE specific lesions. Chapter 4 shows that replacing dietary soyabean meal with potato protein concentrate or canola meal or adding synthetic trypsin inhibitor to the soyabean meal control diet did not induce sub-clinical NE in birds housed on reused litter, a natural source of C. perfringens challenge. Chapter 5 describes that in vitro growth of C. perfringens on in vitro digested grower diets was prolonged following the addition of fishmeal, suggesting that the role of fish meal as a predisposing factor for in vivo sub-clinical NE cannot be excluded. All subsequent diets therefore contained high levels of fish meal. When this was used in combination with high dose of coccidial vaccine, a repeated in-feed challenge for three days at 102 colony forming units (cfu) C. perfringens per g feed did not result in sub-clinical NE, though at 109 cfu/g resulted in 10% of challenged birds (3 out of 30) showing NE-specific lesions (Chapter 6). Further study is needed to determine if the two Ross birds with gross NE lesions compared to the one Hubbard bird (out of 15 birds each) was due to a lower level of NE resistance. 3 The failure to significantly induce sub-clinical NE in the previous experiments suggests that challenging the birds with C. perfringens in the isolated presence of suspected predisposing factors may not provide a suitable experimental model. Indeed, when birds were dosed twice daily with 108 cfu C. perfringens for three days in the presence of high levels of fishmeal, canola meal as main protein source, coccidial and IBD vaccinations, and feed withdrawal prior to challenge, 40.6% of the challenged birds developed lesions of sub-clinical NE without inducing mortality (Chapter 7). This concurred with reduced growth performance relative to the sham-infected control birds, and thus is a successful model for induction of sub-clinical NE. Finally this work has, for the first time provided novel information on potential biomarkers (Chapter 8). Whilst challenge did not impact on the expression of genes previously shown to be differentially expressed upon C. perfringens toxin exposure, the serum ceruloplasmin concentration increased, suggesting that monitoring this acute phase protein may indicate the presence of C. perfringens infection in poultry. However, as such markers generally lack specificity, further research confirming its role in response to sub-clinical NE is needed to provide a fully effective diagnostic and prognostic marker for flock health and welfare, as well as ultimately helping to gain better understanding of the pathophysiology of sub-clinical NE. Improved knowledge of the effect of different dietary components on the growth of C. perfringens may help in the formulation of broiler diets to assist in further reducing the incidence of NE particularly in the absence of antimicrobial growth promoters. It is hoped that host responses in terms of acute phase proteins, and possibley gene expression, will also provide greater insight into the pathogenesis of NE. Provided that the developed experimental sub-clinical NE model is reproducible, this will benefit the understanding of this billion dollar disease and enable further investigation of various chemical and non-chemical interventions to reduce its severity and impact on poultry production.

Active immunisation against GnRH inhibits reproductive function by inducing a hypogonadotropic condition associated with gonadal atrophy. Despite economic, ethical and environmental advantages of GnRH immunisation in cattle over conventional castration methods, the technology has not yet been commercially adopted. Primarily because of the requirement for numerous booster vaccinations because of the reversibility of physiological effects, the commercial efficacy of immunocastration is currently poor. However, neonatal GnRH immunisation in sheep can result in a permanent suppression of reproduction (Brown et al., 1994; 1995; Clarke et al., 1998). These findings and a study in pigs (Molenaar et al., 1993) indicate that, the hypothalamic/pituitary gland unit (HPU) may be particularly susceptible to GnRH antibodies during a specific window of development in the pre-pubertal animal, but no long-term studies in cattle have been conducted. Therefore the primary objective of this project was to determine the effect of neonatal immunisation against GnRH in cattle. Beef cross bull (n=9; Chapter 3) and heifer calves (n=9; Chapter 4) were vaccinated against a newly developed (Pfizer®) GnRH construct vaccine at -2, 6 and 13 weeks of age. Nine calves of each sex served as negative controls, receiving saline injections only. The GnRH vaccine had proved effective (Dr. A.R. Peters, personnel communication 2000) in inducing immune responses and reducing variation between animals in unpublished industrial studies, compared to earlier vaccines, and hence was reasoned to be capable of raising GnRH antibodies despite the relative immaturity of the neonatal immune system. Following vaccination, circulating GnRH antibodies and reproductive hormones, such as FSH (Chapters 3 and 4), testosterone (Chapter 3), progesterone (to assess onset of puberty) and oestradiol (Chapter 4) were measured and additional intensive serial bleeds were carried out to assess LH parameters up to and beyond puberty (puberty defined by testes circumference in bulls). Gonadal (antral follicles and testes growth) and accessory gland development was quantified throughout the trial using ultrasound scanning. Sexual behaviour (Chapter 3) was studied from 38 weeks of age, while an assessment of sperm quality (Chapter 3), and anabolic response to vaccination was also performed post-mortem (Chapters 3 and 4). GnRH immunisation in neonatal calves did not permanently impair reproduction. A temporary suppression in reproductive function was evident through the disruption of pituitary gland function, as indicated by a reduction of LH pulse amplitude and mean plasma LH concentrations (Chapters 3 and 4). In addition, a reduction in medium- sized follicle numbers, testes growth, plasma testosterone concentration, vesicular gland length and juvenile aggression occurred. Some beneficial anabolic effects were observed e.g., carcass composition grades. Changes all occurred subsequent to increased GnRH antibody titres in immunised cattle. Despite some evidence of prolonged effects on LH amplitude and circulating testosterone after anti-GnRH titres had dissipated, all inhibited parameters, except carcass quality, returned to levels comparable to control animals by 72 weeks of age. No treatment effects on FSH concentrations, large follicle numbers, reproductive tracts (post mortem) or peri- and post-pubertal behaviours were observed following treatment. Sperm morphological abnormalities tended to be more prevalent in GnRH immunised bulls. A significant increase in GnRH antibody titres occurred at -23 weeks of age (Chapter 4), this may have been a rebound in antibody titre, possibly caused by an anti-idiotype immune response (antibody response to GnRH antibodies), or due to significant maturational changes in immune function at this time causing a delayed response to vaccination. Alternatively a novel "auto-immune" response may have been detected, which if confirmed/repeatable might be incorporated into an immunisation protocol to act as a "self-booster". However, no previous reports of such an event have been published and further investigation is urgently required. A more prolonged or permanent suppression of reproductive function may be possible following an earlier, greater and more sustained elevation of antibody titres during the neonatal period. Further development of GnRH vaccines and/or protocols (prime-boost, cytokine modulation vaccines, concomitant passive and active immunisation and pregnant cow GnRH vaccination), and studies of performance and GnRH antibody mechanism(s) of action in cattle are required. Chapters 3 and 4 provide a comprehensive study on pubertal development and neonatal GnRH vaccination, thus contributing significantly to knowledge in these fields. Currently, the vaccine used in this trial may be used to delay puberty in older calves or transiently suppress reproductive function to aid management. The economical viability of animal production systems such as beef and lamb are closely related to rates of reproduction. The Fec B gene in ewes increases ovulation rate and litter size, possibly through the development of precocious follicles, which can switch their primary dependence from FSH to LH. As a result, more follicles are selected to continue growth to an ovulatory size. The precise mechanisms by which these processes occur have recently been shown to involve oocyte follicle interactions (see section 1.1.5). Follicle development is modulated by GHIIGF and inhibin, however attempts to increase follicular development and ovulation through active inhibin immunisation alone have been variable and hence not commercially attractive. To develop successful protocols to induce twin ovulations in cows· and ewes, without superovulation, a clearer, more details understanding of follicullogenesis is required. The objective of the current study was to better understand these mechanisms through investigating interactions of GH/GF and inhibin in the ovary, follicle development, steroidogenesis, and receptor populations using an anoestrous sheep model. Spring born Mule x Charolais ewe lambs were actively immunised (n=8) against porcine inhibin α-C 1-26 peptide conjugated to KLH in NUFCA (primary and 3 boosters (NUFA», while 8 served as negative controls. Seven days following the final booster, the ewes were subdivided to give four groups: (1) controls + saline (n=4); (2) controls + rbGH (4ml s.c; 1mg. mr1; n=4); (3) inhibin immunised + saline (n=4); and (4) immunised + rbGH (n=4). Recombinant bovine growth hormone (rbGH) was given (Lm.) for 6 days. On day 4 GnRH (Receptal®; 1 ml) was injected s.c, to all animals to initiate the beginning of a new follicular wave. Blood samples were collected fortnightly to measure inhibin antibody titres, IGF-I, FSH and steroids. On the seventh day ensuing slaughter serum antibodies and ovaries were harvested. Left ovaries were intended for ISH (mRNA for P450arom) and/or immunohistochemical analysis. Follicles from right ovaries were dissected out, counted, measured and cultured in M199 at 37°C for 2 hours. Culture media was then assayed for oestradiol. Follicle shells were stored at -180°C for LH receptor binding studies. This work reports on the influence of different treatments on follicle populations. All immunised animals produced antibodies, which bound to 1251-inhibin. Using ANOVA to compare treatments it was observed that, Inhibin immunisation significantly (P<O.05) increased the number of follicles >3.5mm in diameter, but did not affect the smaller <3.5mm population. In contrast, rbGH administration led to a significant (P<O.05) elevation of follicles <3.5mm, without increasing the >3.5mm follicle numbers. These findings are in agreement with previous research. The molecular studies of left ovaries are not presented herein as due to time constraints the work was not completed and is currently on going. In conclusion, additional results of this study are required to meet the objectives of the experiment. Further research is required on dominant follicle selection if superovulatory programmes in both livestock and humans are to be more precisely controlled and readily accepted.

The thesis examined the effects of climatic change on livestock production within Scotland. In order to achieve this, a systems model of the dairy, beef and sheep enterprises was developed. Climatic change primarily affects livestock production through its effects on forage production. Under climatic change, the model predicted that the length of the growing and grazing season will increase with the extensions occurring at both ends of the season. Relative to current climatic conditions elevated CO2 concentrations coupled with the associated changes in climate resulted in an enhancement in harvestable dry-matter yield that ranged from 20% to nearly 60% and increases in the percentage of white clover in the harvestable material by up to 126% In general, global warming is predicted to increase forage and livestock production within Scotland. However, the location of the site is also important in determining the effect of climate change as the magnitude and, in some cases, the directions of the changes varied between sites. The effects of climate change were also dependent on the actual level of changes in temperature. In addition, there were interactions between CO2 concentration and both temperature and rainfall, as well as interactions between temperature and rainfall. Although the three enterprises showed similar trends in their response to climate change, there were differences in the magnitude of the response as well as differences in the factors that resulted in significant changes. There were also differences in the response of the grazed and the ungrazed swards. This underlines the complexity of the interactions and the difficulty of extrapolating the results to other locations and to other levels of climatic conditions. The advantage of developing a model is that all these complex interactions can be captured and potentially the site - specific consequences of climate change on forage and livestock production predicted.

Malignant catarrhal fever (MCF) is caused by two closely associated gamma herpes viruses namely alcelaphine herpesvirus 1 (AlHV-1) and ovine herpesvirus 2 (OvHV-2) and characterised with lymphocyte infiltration in non-lymphoid tissues, vasculitis and epithelial damage. The mechanism by which the viruses cause the disease is not fully understood. The hypothesis of this project was that MCF is initiated by aberrant gene expression in endothelium, epithelium and infected T cells of susceptible animals, because they are not the natural hosts for the viruses and the viruses will not have evolved in them. The first goal was to examine whether rabbit epithelium and bovine endothelium can be infected in vitro and in vivo with AlHV-1 using q PCR and, if infected whether viral transcripts could be identified in these tissue cells using q PCR and in situ hybridisation (ISH). The results revealed that endothelium and epithelium can be infected and latent infection can be established in them. This suggests the likelihood of establishing a similar type of infection in vivo. Secondly, the trial to identify latency-associated transcripts using 5-azacitidine treatment on bovine turbinate fibroblast (BT) cells and rabbit large granular lymphocytes (LGLs) was only partially successful. However, pan T antigen was expressed in 5-azacitidine treated but not untreated LGLs cells. This may indicate a function of the drug either directly or through the latency state. Transcriptome analysis in the infected and treated LGLs and BT cells showed that several pathways were affected by 5-aza although a possible latency (low transcript levels) was only seen in the BTs. Transcriptome analysis revealed similar pathways to those described for MCF in the tissues in vivo, and an effect of 5-aza on these. Viral transcripts analysis showed that genes related to productive/lytic cycles were higher than latent ones on day 17 of the in vivo experiment demonstrating that the virus may replicate at this stage of the disease. The attempt to localize the viral transcripts on the rabbit infected tissues using ISH was unsuccessful due to a lack of time.

The overall objective of this thesis was to study the effects of regular and high (super-) doses of phytase in the gut of broilers, with the aim of documenting the mechanism of their action leading to improvements in animal health. Phytase is often supplemented to commercial broiler diets to facilitate the hydrolysis of plant phytate and release of phosphorus for utilisation. Although not the original intention of its addition, phytase supplementation leads to improvements in growth performance parameters and enhanced nutrient utilisation. Further benefits have also been observed following the addition of super-doses of phytase which are not explained by an increase in phosphorus release, and thus have been termed ‘extra-phosphoric effects’. Using diets formulated to be adequate or marginally deficient in available phosphorus (aP) forming the negative control, NC), phytase was supplemented at 1,500 and 3,000 FTU/kg phytase in the first study (both super-doses) and the partitioning of nutrients within the body was investigated. It appeared that there were some metabolic changes between 1,500 and 3,000 FTU/kg, switching between protein and fat accretion, potentially as a consequence of nutrient availability, although these changes were not reflected by changes in growth performance parameters. However, the loss of the NC treatment without phytase on day 12 limits the comparison of the phytase within the NC treatment, but does allow for comparison of each dose at adequate or low dietary aP levels. As expected, a greater degree of phytate hydrolysis was achieved with 3,000 than with 1,500 FTU/kg phytase, but changes in carcass accretion characteristics were greater with 1,500 than 3,000 FTU/kg. Using these findings and the observation that there were no further changes in the parameters measured by increasing phytase from 1,500 to 3,000 FTU/kg (aside from phytate hydrolysis), 1,500 FTU/kg phytase was selected as the super-dose to be used in subsequent studies. The next study considered the influence of regular (500 FTU/kg) and super doses (1,500 FTU/kg) of phytase from within the gut. Overall, it was observed that changes were occurring to the gut environment, which ultimately would influence the absorptive capacity and conditions for further phytate hydrolysis. Dietary treatment influenced gut conditions such as pH, intestinal morphology and bacterial populations which can subsequently influence nutrient utilisation and potential for growth. The subsequent study was designed to investigate the effects within the gut in more detail. The release of nutrients from phytate hydrolysis and their bioavailability within the digesta can influence conditions within intestine, facilitating enhanced absorption. One of the parameters investigated was the expression of genes involved in the transport of nutrients in the intestine. Overall, there were few significant dietary treatment influences on gene expression in the intestine, however there was a dose-dependent response of phytase on the expression of the jejunual divalent mineral transporter. This indicates a change in divalent mineral bioavailability in the intestine, with correlations with inositol phosphate esters (IPs) being identified. This is likely explained by the IPs produced by phytase hydrolysis and accumulating in the digesta, differing between regular and high doses of phytase. It became apparent that interactions between the products of phytate hydrolysis (IP3, IP4) and minerals in the digesta had the potential to influence the gut environment and subsequent nutrient bioavailability and overall phytase action. The final study was designed to increase the content of the IPs, and investigate the influence of phytase under these conditions. As the complete hydrolysis of phytate to myo-inositol has been reported to be beneficial due to its proposed insulin mimetic effects, myo-inositol was also supplemented to one of the diets to see if any further benefits would be observed when supplemented alongside super-doses of phytase. Neither increased concentrations of the higher IP esters (IP6, IP5 and IP4) nor myo-inositol (myo-) had any effect on broiler growth performance, however there were still apparent beneficial influences of phytase supplementation. The results suggest considerable and important interactions between minerals and IP esters within the digesta, which ultimately have the potential to influence gut conditions and thus nutrient utilisation and growth performance. Reduced concentrations of blood glucose in the high IP ester diet with additional phytase supplementation suggest some insulin-like effects of myo- production. Additionally, the lack of effect of myo- supplementation on blood glucose and insulin concentrations suggests a difference between the structure of phytase-produced myo- and supplemented myo-. Although there were no improvements in growth performance by increasing phytase from 500 to 1,500 FTU/kg, there were changes occurring at the level of the gut and expression of genes in the intestine, influencing nutrient utilisation and the partitioning of nutrients within the body. There are many factors to be considered when supplementing phytase, with dietary nutrient content and nutrient release and IP production during phytate hydrolysis having an influence on phytase action, nutrient absorption and conditions within the gut. Super-doses of phytase may be beneficial for maintaining optimal gut conditions, clearing IP esters from the digesta, reducing their potential to form complexes with minerals and other nutrients, ultimately influencing the efficiency of production.

Adipose tissue is found in two main forms: white (WAT), which stores energy; and brown (BAT), which dissipates energy as heat by means of a unique mitochondrial protein, UCP1. In large mammals, BAT is rapidly replaced by WAT after birth, but it has recently been found that functional BAT is present in human adults, which raises the possibility that it could be manipulated to burn off excess fat. The main aim of this thesis was to investigate, using sheep as a model, the effect of early nutritional interventions on fat mass and on the expression in adipose tissue of genes involved in adipogenesis, metabolism, thermogenesis and development. A secondary aim was to study their ontogeny in sternal adipose tissue. Study A examined the effect of fat supplements given to lactating ewes on the sternal adipose tissue of their offspring. Ewes were allocated to one of three feeding groups, one control and two supplemented (sunflower or canola oil), for 28 days after parturition, and their lambs were sampled at 7 and 28 days of age. Study B investigated the effect of late gestational and postnatal diet on the sternal and subcutaneous adipose tissue of 6 month-old lambs. Twin-pregnant ewes were divided into three dietary groups for the last 6 weeks of gestation: undernourished, control or overnourished. One lamb from each twin pair was fed a control diet, and the other a high-carbohydrate, high-fat (HCHF) diet. In the first month after birth, changes in gene expression in sternal adipose tissue were comparable to those previously described in perirenal adipose tissue, with the expression of most thermogenic genes declining to almost undetectable levels by 28 days of age. There was a disparity in the expression profiles of the two principal regulators of adipogenesis, PPARγ and C/EBPα, with expression of the former increasing with age, and that of the latter peaking at 7 days of age. A sunflower, but not canola, oil supplement fed to lactating ewes increased the relative adipose tissue weight of female, but not male, lambs at 28 days of age. Both supplements increased the plasma concentration of leptin at 7 and 28 days of age in females, but not males. Supplementation had a greater effect on gene expression at 7 than at 28 days of age, but no overall pattern emerged. Maternal undernutrition reduced birth weight in males, but not females, although body weight was unaffected by 6 months of age. A postnatal HCHF diet increased fat mass in all adipose tissue depots tested, and reduced expression of most adipogenic and metabolic genes in sternal and subcutaneous adipose tissue by around 50 %. Expression of thermogenic genes was barely detectable in either tissue at 6 months of age. In conclusion, expression of thermogenic genes in sternal adipose tissue declines with age, a response that is unaffected by maternal fat supplementation during lactation or a sustained postnatal HCHF diet.

The objective of this work was to investigate whether or not olfactory clues play a role in host plant location by the polyphagous moth, Helicoverpa armigera. Volatiles collected from flowers of African marigold, Tagetes erecta, and sweet pea, Lathyrus odouratus, were found to elicit electroantennographic (EAG) responses from the antennae of female H. armigera. Compounds active in GC-EAG analyses of T. erecta floral headspace samples, identified by GC-MS and comparison of retention times on polar and non-polar GC columns with authentic standards, were (E)-myroxide, benzaldehyde, (f)-linalool, phenylacetaldehyde and (-)- piperitone. EAG-active compounds in L. odouratus floral headspace samples were identified as diacetone, (-)-linalool, phenylacetaldehdyde and benzyl alcohol. Increases in upwind flight to air entrained extracts of floral odours indicated that these cues caused attraction when presented to female H. armigera. A synthetic T. erecta blend comprising benzaldehyde, (f)- linalool, phenylacetaldehyde and (+)-limonene gave significant increases in upwind flight approaches. Limonene (either (+)- or (-)-) was found to be important for the behavioural response despite having low EAG-activity. There was no significant difference in upwind flight response to odours from the live flower and the synthetic floral blend. Significant increases in upwind flight were also obtained when insects were presented with a synthetic L. odouratus blend which contained the four EAG-active compounds identified from GCEAG studies. In field trapping experiments in Israel there was a significant difference in H. armigera catches in traps with a standard 4-component T. erecta lure compared with unbaited traps over the whole season. Mean H. armigera catch per trap per night (both sexes) over the whole season in unbaited traps, floral odour traps, pheromone traps and light traps were 0.004,0.11,8.8 and 1.35 respectively. The floral baited traps were non-selective catching large numbers of Ilymenoptera and Diptera as well as other moth species. Field trapping experiments in Pakistan indicated that the floral lure was significantly attractive to Earias spp. and other Lepidoptera although very few H. armigera were caught due to low population density. Olfactory cues are discussed in relation to host-plant finding behaviour of H. armigera. They are involved in early stages of host seeking behaviour prior to alighting on the plant and stimulate searching behaviour.