Amino acids (AA) are required for protein accretion and the need for a specific AA depends on the physiological status, breed, and the health of the pig. Inasmuch as the AA requirements for growing pigs are given in an ideal AA ratio for protein accretion, the utilization of all AA is beyond growth and at least 30% of the total dietary AA will be used by the splanchnic tissue. A ban in the use of antimicrobial growth promoters (AGP) in piglets’ diets is likely to increase incidences of disease occurrence and exert additional AA requirements. Immune challenge models were used to determine standardized ileal digestible (SID) Lys and sulfur amino acids (SAA):Lys requirements for piglets under an antibiotic-free feeding regime. The first objective was to establish the dietary Lys requirement for piglets raised under both clean and unclean sanitary conditions. The Lys requirement could not be determined in the first experiment. However, from the second and third experiments the dietary SID Lys content for optimal growth of 7 to 16 kg weaned piglets was estimated to be 1.32%. The objective of fourth experiment was to determine the optimum SID SAA:Lys ratio in piglets when reared under clean or unclean conditions. Based on performance parameters, the optimum SAA:Lys ratios were 58 and 61 for piglets raised under clean and unclean conditions, respectively. However, VH estimates were 60 and 66 SAA:Lys under clean and unclean sanitary conditions, respectively. The objective for the fifth experiment was to determine SID SAA:Lys ratio of piglets under an enterotoxigenic Escherichia coli challenge using genes for expression of key products in the Met metabolic pathway. Gene expressions of methionine adenosyltransferase 1 and 2-α, 5-methyltetrahydrofolate-homocysteine methyltransferase, and cystathionine γ-lyase was done for liver and ileal tissue. The gene expressions indicates that the dietary SAA:Lys ratio of 60 was enough to support piglet’s immune response and performance during an immune challenge. Therefore, under an antibiotic-free feeding regime, the Lys requirement recommended by NRC (2012) is sufficient, however, the SAA:Lys should be raised to 60 in diets of both healthy and immune challenged piglets.

Cognition, defined as the mechanism by which an animal acquires, processes, stores, and uses information present in the environment, is a trait that is sensitive to developmental conditions. Existing research supports the idea that the ability to develop and maintain cognitive abilities depends on the physiological condition of the individual, which can be influenced by the early environment. Alterations in maternal care, social stress, and malnutrition are some examples of environmental conditions that impact development and resulting cognitive abilities across taxa. The primary goal of this research was to determine whether immune system challenge during the critical song learning period in zebra finches (Taeniopygia guttata) would lead to long term negative impacts on song quality and learning, spatial learning, and neophobia. Immune challenge during this period of development did not produce long term impacts on learning or memory, nor did it lead to any changes in neophobic responses. However, birds that were hatched later in a clutch performed better on the motoric and spatial tasks, and were less neophobic. Future research in zebra finches that can describe the variation in song attributes as a function of hatching order would be a useful first step in determining a mechanistic link between hatch order and song learning outcomes. / Master of Science

Puberty is a critical period of development characterized by rapid physiological changes and significant brain reorganizing and remodeling. These rapid changes render the developing brain particularly vulnerable to stress and immune challenge. In mice, exposure to an immune challenge (lipopolysaccharide; LPS) during puberty causes enduring effects on stress reactivity, cognitive functioning, and depression- and anxiety-like behaviors later in life. However, the mechanisms underlying these effects are unknown. The gut microbiome can profoundly influence the immune system. There is also close bidirectional communication between the gut microbiome and the central nervous system (CNS) through neural, endocrine and immune signaling pathways, which can alter brain chemistry and emotional behaviour. Thus, we hypothesized that altering microbial composition during puberty could mitigate acute immune responses and prevent enduring outcomes later in life. The current thesis examined the effect of gut manipulation with probiotics during puberty on LPS-induced immune responses and enduring anxiety- and depression-like behaviours, and stress-reactivity in adulthood, in male and female CD1 mice (Article 1). Next, we examined age and sex differences in gut microbial composition before and after exposure to an immune challenge. We also examined the effects of consuming a single strain probiotic bacterium (Lactobacillus Reuteri) during puberty on the immune response and the long-term changes in memory, anxiety-like behavior, and stress reactivity in adulthood (Article 2). Lastly, we examined how microbial colonization between pubertal and adult mice can alter acute peripheral and central inflammatory responses to LPS (Article 3). The current dissertation has addressed sex-specific vulnerabilities to an immune challenge during pubertal development and the moderating influence of the gut microbiome. These studies have demonstrated that manipulating the gut microbiome during puberty can mitigate acute immune responses and prevent enduring neurobehavioural outcomes later in life.

<p>Animal behavior observation is a widely used method of detecting when animals are ill or injured, but there are limitations to using behavioral observations. Behavioral observations can be labor-intensive, subjective and unreliable. The development of technologies such as accelerometers, which record acceleration and activity-based data in 3D space, enables faster, more accurate and quantitative methods of detecting changes in animal behavior. Previous research has demonstrated the utility of using accelerometers to detect changes in animals’ health and well-being. However, limited information is available on the use of accelerometers to detect changes in behavior due to heat stress, which is a major poultry welfare concern, or to detect changes in activity levels of turkeys. The overall objective of this study was to determine whether micro-acceleration data loggers (accelerometers) can be used to detect changes in turkeys’ activity levels and to identify changes in turkey behavior that are indicative of changes in turkey well-being. Two trials were conducted. Specific objectives for Trial 1 were to: 1) determine the effects of accelerometers and habituation to accelerometers on turkey gait and welfare, 2) determine age-related changes in gait and welfare, and 3) evaluate the validity of the accelerometers. Thirty-six male commercial turkeys were randomly assigned to one of five groups: accelerometer and habituation period (AH), accelerometer and no habituation (AN), VetRap bandage (no accelerometer) and habituation (VH), bandage (no accelerometer) and no habituation (VN), and nothing on either leg (C). Welfare was assessed prior to video-recording birds as they walked across a Tekscan® pressure pad at 8, 12 and 16 wk to determine effects of treatment on number of steps, cadence, gait time, gait distance, gait velocity, impulse, gait cycle time, maximum force, peak vertical pressure, single support time, contact time, step length, step time, step velocity, stride length, total double support time, and duty factor. Accelerometer validity and reliability were determined by comparing the number of steps detected with the accelerometer to the number of steps determined from video recordings. Several age-related changes in turkey gait were found regardless of habituation, including a slower cadence at 16 wk, shorter gait distance at 8 wk, and slower gait velocity at 16wk. Habituation to the accelerometer and bandage had limited effects on turkey gait: non-habituated turkeys (VN and AN) spent more time standing on two feet (total double support time) compared to C birds, but did not differ from habituated (VH and AH) birds. Accelerometer validity and reliability were affected by both age and treatment. Validity and reliability were lowest for non-habituated birds (AN). Precision and sensitivity of accelerometers decreased with age but were unaffected by treatment. False discovery rate increased, and accuracy and specificity decreased with age. Results demonstrated that micro-data loggers do not adversely affect turkey welfare, but habituation to wearing accelerometers affects accelerometer reliability and validity. Accelerometer validity and turkey gait are also greatly affected by the age of the turkeys. </p> <p> </p> <p>The second experiment used the validated accelerometers to assess changes in walking activity when turkeys were under an immune challenge or mild heat stress. Another objective of Experiment 2 was to identify changes in welfare and behavior associated with mild heat stress and a mild immune challenge. A total of 92 tom turkeys (trial 1: 51 turkeys; trial 2: 41 turkeys) were assigned to 3 different treatments in a crossover design: control (C; no heat stress or immune challenge), heat stress (HS), and immune challenge (IC). HS treatment was induced by slowly heating rooms to a peak temperature before slowly returning the rooms to normal temperatures. IC treatment was induced by a live-virus hemorrhagic enteritis vaccine which was added to the drinking water. Video (walking, sitting, standing, eating, drinking, preening, feather pecking, aggression and heat-stress related behavior) and accelerometer (steps/hr) data were recorded for 5 days at 10, 12, and 14 wk of age in order to gather behavior and walking activity data pre and post treatment, which occurred on day 3 of the 5 day period. Steps/hr decreased with age, treatments HS and IC had lower step counts compared to control groups, and each day proved to have a different step count regardless of whether a treatment was imposed. On the day of the imposed treatments, steps/hr were lower for both HS and IC turkeys. Welfare analysis indicated that tail and wing feather condition was worse at 14 wk compared to 10 and 12 wk. Behaviorally, the amount of time spent sitting increased as birds aged. Treatment also affected behavior: HS and IC turkeys performed less standing and walking compared to C birds on the day of the imposed treatment. Turkeys under a heat stress treatment performed more aggressive interactions and were observed performing heat-stress related behavior, including panting and sitting with their wings spread apart. </p> <p> </p> <p>Results from both trials indicated that accelerometers can be useful tools to assess walking activity of turkeys and that accelerometers have the potential to detect changes in behavior that may be associated with conditions that negatively impact turkey welfare. The process of wearing an accelerometer on the leg did not adversely affect turkey welfare, but habituation is important to ensure that accelerometers are accurately and reliably recording turkeys’ steps. In addition, it was determined that changes in behavior, such as decreased walking and standing, can be indicative of potential welfare issues, such as heat stress and an immune challenge in turkeys. Further research is needed to explore the best step threshold for particular turkey ages in order to get the most accurate data in future analysis of walking activity. Furthermore, sex differences were not a factor in these studies as only male turkeys were used which may differ from females in terms of gait and behavior under heat stress and an immune challenge. It may also be beneficial to further explore turkey gait as there were discrepancies in the literature and this study concerning age related differences in gait (duty factor). Future research should focus on the early detection potential accelerometers can provide to the turkey industry for welfare concerns. As shown by our results, walking activity decreases under both a mild heat stress and immune challenge, so future studies should now determine if this decrease in activity level is detectable before overt visual behavioral signs. If accelerometers can detect signs of stress more objectively, accurately, and quicker than visual inspection, then both farmers and researchers could benefit from utilizing these devices to improve animal welfare in the future.</p>

<p>Immune-brain communication has important influences on stress circuitry and stress-related behaviours. Adaptive immune deficiency through loss of lymphocytes or an absence of gut bacteria has been linked to anxiety behaviours and stress responsiveness. In these models, there is a common deficit of T lymphocytes leading to the central hypothesis that T lymphocytes influence stress responsiveness and stress-related behaviours. This project considers the effects of T lymphocyte deficiency on anxiety and fear related behaviours as well as stress responsiveness in the hypothalamic pituitary adrenal (HPA) axis. Mice lacking T lymphocytes through knockout of the T cell receptor (TCR) β and δ chains, and B lymphocytes through knockout of the immunoglobulin M μ chain, were obtained and compared to C57BL/6 control mice. Activity, exploration, anxiety, fear and spatial learning tests were employed. Separately, gene expression was assessed for genes related to stress circuitry following chronic restraint stress. Additionally, lipopolysaccharide was used to determine the stress response to an innate immune challenge that was previously shown to elicit an exaggerated stress response in mice lacking Class I Major Histocompatibility Complex (MHC) and CD8+ T lymphocytes. It was found that mice lacking T lymphocytes, but not B lymphocytes, have reduced anxiety-like behaviour but an increased fear response. TCRβ-/-δ-/- mice also had altered expression of components of the HPA axis, serotonergic receptors and NMDA receptor subunits indicating an altered response to chronic stress. Finally, TCRβ-/-δ-/- mice do not display an exaggerated stress response to an innate immune challenge suggesting a central role for Class I MHC in the stress response that is not due to the CD8+ T lymphocyte deficiency that accompanies the functional loss of Class I MHC. These studies reflect an important role for T lymphocytes specifically in the development of the stress system and stress-related behaviours and enables a deeper understanding of neuroimmune influences on stress.</p> / Doctor of Philosophy (PhD)

L'étude porte sur l'allocation de ressources aux œufs d’oiseaux selon les caractéristiques du male partenaire ou de l’environnement. les données étudiées sont : taille de la ponte et caractéristiques des œufs (masse, masse des constituants, concentration de testostérone, lysozyme, ovotransferrin). les caractéristiques du male prises en compte sont s'il est choisi ou non par la femelle et son statut social. en plus, l’effet du bruit et d’un vaccination couple avec un surproduction des œufs sont pris en compte. Deux expériences ont été menées sur le canari domestique (Serinus canaria) en laboratoire, au sein du LECC de Paris Ouest Nanterre. Deux expériences ont eu lieu en milieu semi-naturel au DiSIT de l’Università degli Studi del Piemonte Orientale (Italie) sur la perdrix grise (Perdix perdix) et rouge (Alectoris rufa).Chez la perdrix grise, nous observons effets positifs de la préférence et du statut social sur la testostérone et sur le taux d’éclosion. cette hormone peut rendre les oisillons nidifuges plus compétitifs vis-à-vis des couvées voisines. Chez le canari, on observe un effet positif de la préférence sur le poids des œufs et sur le lysozyme, important substance antimicrobienne. en plus, on a trouvé un influence négative du bruit sur la sélection sexuelle et sur le numéro des œufs pondues.Chez la perdrix rouge, nous observons variations significatives des components de l’oeuf en relation a la surproduction des œufs (épuisement des ressources). En conclusion, la femelle n'est pas seule à déterminer les caractéristiques des œufs. le male partenaire et l’environnement ont aussi une influence sur leur composition et donc sur le développement des jeunes. / The study focuses on the allocation of resources to eggs of birds according to the characteristics of the male partner or the environment. The data studied are: clutch size and egg characteristics (mass, mass constituents, testosterone, lysozyme, ovotransferrin). Male characteristics taken into account are if it is selected or not by the female and his social status. In addition, the effect of noise and a vaccination coupled with an overproduction of eggs are taken into account.Two experiments were conducted on the domestic canary (Serinus canaria) in the LECC laboratory of Paris Ouest Nanterre.Two experiments were carried out in semi-natural condition to DiSIT laboratory of the Università degli Studi del Piemonte Orientale (Italy) on grey partridge (Perdix perdix) and red-legged partridge (Alectoris rufa).In the grey partridge, positives effects of preference and social status are observed on testosterone and hatchability. This hormone can make precocial chicks more competitive with neighboring broods.In canaries, there is a positive effect of preference on egg weight and lysozyme, an important antimicrobial substance. In addition, a negative influence of noise is found on sexual selection and number of eggs laid.In the red-legged partridge, significant changes in the egg components are observed in relation to the overproduction of eggs (depletion).In conclusion, the female is not only to determine the characteristics of eggs. The male partner and the environment also have an influence on their composition and therefore on the development of chicks.

Le récepteur activé par les proliférateurs de peroxysomes (PPAR) b/d est un facteur de transcription impliqué dans l’activation de la voie d’oxydation des lipides qui possède également une fonction anti-inflammatoire. Étudié chez les macrophages, son rôle reste très peu connu dans d’autres cellules immunitaires comme les lymphocytes T. Nous avons généré un nouveau modèle murin où PPARb/d est surexprimé spécifiquement dans les lymphocytes T (souris Tg T-PPARb), afin d’étudier l’effet de sa surexpression sur le développement ainsi que la fonction des lymphocytes T grâce à deux types de challenges : métabolique et immunitaire. Nos résultats ont permis de mettre en évidence un rôle de PPARb/d dans le développement des lymphocytes T ab (blocage de leur développement) mais pas des lymphocytes T gd. On observe alors une diminution de 70% du nombre de lymphocytes T ab dans les organes lymphoïdes conduisant à une diminution du ratio de Lymphocytes T ab/gd. Les lymphocytes T ab qui arrivent tout de même à se développer ne surexpriment pas PPARb/d. Au cours d’un challenge métabolique (régime hyperlipidique), nous avons observé que les souris Tg T-PPARb sont partiellement protégées contre l’obésité. Elles présentent également une amélioration de leur phénotype métabolique (sensibilité à l’insuline et au glucose, stéatose hépatique) et inflammatoire (diminution de l’inflammation des dépôts de tissus adipeux). Au cours d’un challenge immunitaire (injection de LPS), nous observons une diminution du nombre de macrophages pro-inflammatoires M1 dans la cavité péritonéale des souris Tg T-PPARb dès 1h post-injection. Chez les souris contrôles, ce phénomène est visible à partir de 3h postinjection de LPS. Il semble ainsi que la réponse immunitaire des souris Tg T-PPARb soit plus précoce que celle des souris contrôles en réponse à un challenge immunitaire. En conclusion, la surexpression de PPARb spécifiquement dans les lymphocytes T semble provoquer une altération des populations de lymphocytes T ainsi qu’une potentielle modification de leur fonction qui pourraient expliquer que les souris Tg T-PPARb réagissent mieux que les souris contrôles lorsqu’elles sont soumises à différents types de challenges (immunitaire ou métabolique). / The Peroxisome Proliferator Activated Receptor (PPAR) b/d is a transcription factor involved in the activation of the lipid oxidation pathway that also has an anti-inflammatory function. While well-studied in macrophages, its role in other immune cells like in T cells remains largely unknown. We have generated a new mouse model in which PPARb/d is specifically overexpressed in T cells (Tg T-PPARb mice) and studied the effect of its overexpression on the development and the function of T cells through two types of challenge: metabolic and immune. Our results show a role of PPARb/d in the development of ab T cells (blocking their development) but not gd T cells. There is then a 70% decrease in the number of ab T cells in lymphoid organs leading to a decrease in the ab/gd T cell ratio. ab T cells that are still able to develop do not overexpress PPARb/d. During a metabolic challenge (high fat diet), we observed that Tg T-PPARb mice are partially protected against high fat diet inducedobesity. They also show an improvement in their metabolic (insulin and glucose sensitivity, hepatic steatosis) and inflammatory phenotype (decrease in inflammation in adipose tissue depots). During an immune challenge (LPS injection), we observed a decrease in pro-inflammatory M1 macrophage number in the peritoneal cavity of Tg TPPARb mice at 1h post-injection. In control mice, this phenomenon is seen at 3h post-injection of LPS. Thus, it appears that the immune response in Tg T-PPARb mice is faster than the one in control mice in response to an immune challenge. In conclusion, PPARb/d overexpression specifically in T cells appears to cause an alteration in T cell population as well as a potential change in their function which could explain that Tg T-PPARb mice respond better than control mice when they are subjected to different types of challenges (immune or metabolic).

<p>  </p> <p>In commercial settings, piglet weaning and transportation occur concurrently due to the expansive application of multi-site production systems across the United States and the combination of these events can be defined as an early life stressor. Early life stress is known to reduce pig performance, efficiency, and immune resilience contributing to reduced welfare and increased production losses. To combat the deleterious effects of stress on pigs, the essential amino acid tryptophan (Trp) supplemented above current National Research Council (NRC 2012) recommended levels, improves neuroendocrine responses to stress, lowers plasma cortisol and norepinephrine concentrations, and improves hypothalamic-pituitary-adrenal axis recovery time following stress. However, there are discrepancies concerning the Trp requirement for nursery pigs, suggesting the 2012 recommendations for Trp may be inaccurate for optimizing growth performance and health in modern pigs. Three experiments were conducted to determine the effects of supplemented standard ileal digestible Trp above NRC (2012) recommended levels on performance, feed efficiency, immune vigor, and stress tolerance. The objective of experiment 1 was to eliminate or reduce short- and long-term, transport-induced reductions in piglet feed efficiency and growth by supplementing Trp above NRC (2012) recommendations pre-weaning and/or during the nursery phase. An oral gavage of Trp or a control milk carrier was provided to pre-allotted piglets beginning at day 5 of lactation and continuing to weaning. At weaning all pigs were blocked by sex, weaning weight and pre-wean treatment and randomly assigned to transport and post-wean treatments. Pigs were fed in four nursery phases with diets containing 1X or 2X NRC recommended concentrations of SID Trp and a common grower diet fed in 6 phases during the grow-finish period. At market, loin characteristics were measured via ultrasound and carcass data was collected from the packing plant. Pre-weaning Trp supplementation had no effect on pre-weaning growth performance; however, post-wean Trp increased overall body weight and average daily gain in nursery pigs when Trp was supplemented pre-wean. The objective for experiment 2 was to mitigate the adverse effects of early life transport stress on subsequent immune challenges by providing supplemental Trp during the nursery period. At weaning, pigs were transported for 8 hours and assigned to treatments of vaccine-induced immune challenge and dietary treatment. Pigs were fed standard nursery diets, in four phases, over 35 days with pigs receiving 1X or 2X the NRC (2012) recommended Trp concentration. Half the pigs on each dietary treatment were subjected to a 3-wk vaccine challenge consisting of circovirus, mycoplasma, and influenza vaccines administered in wk 2, 3, and 4 post-wean, respectively. At market, loin characteristics were measured via ultrasound and carcass data was collected.  At the culmination of the nursery period, unchallenged pigs supplemented with Trp were heavier compared to control pigs. This resulted from an overall improvement in average daily gain for 2X Trp fed pigs. However, increasing Trp did not affect market weight, loin eye area, or lean percent in market pigs, although 2X Trp increased back fat. The objective of experiment 3 was to determine what ratio of SID tryptophan, relative to lysine, maximizes growth performance and feed efficiency in weaned pigs during the nursery period. Pigs were blocked by sex and weaning weight and randomly allotted to one of five dietary treatments with Trp increasing stepwise by 0.33%-units, respectively. Pigs were fed standard nursery diets, in four phases, over 35 days with pigs receiving 1X, 1.33X, 1.66X, 2X, or 2.33X the NRC (2012) recommended Trp concentration.  Overall, there were no differences in performance or efficiency across dietary treatments during a 35-day nursery period in unstressed healthy pigs.  In conclusion, increasing Trp in swine diets prior to and/or following stress events can mitigate stress-related perturbations in performance and efficiency.      </p>