C3d is a sub-fragment of the C3 component of the complement system.  Covalent binding of multiple C3ds to antigen reduces the activation threshold of cognate B lymphocytes by one thousand fold through co-ligation of the BCR and complement receptor 2 (CR2/CD21). Reverse transcriptase polymerase chain reaction (RT-PCR), revealed that, in cattle, four distinct complement receptors are produced from the Cr2 gene by alternative splicing. Cattle express two major variants of the Cr2 gene representing homologues of murine CR1 and CR2, each of which are expressed in both a long and a short form. Expression of CR1 was detected in splenocytes but not in splenic mononuclear cells or monocyte derived macrophages. CR2 was detected only on IgM+ blood cells and unsorted splenocytes but not in CD3+ cells, CD14+ cells or neutrophils. Additionally, the coding sequence of CD19, the CR2 co-signaling molecule was found.

The objectives of this thesis were to investigate 1) the use of behavior and activity monitoring for the identification of heifers at risk of disease, 2) the use of group level management practices to reduce the risk of disease, and 3) the identification of long-term impacts of bovine respiratory disease complex (BRD). For objective 1, lying posture, a decreased willingness to approach an observer and high lethargy scores were associated with diarrhea in calves under 2 weeks of age and a high lethargy score in 4-6 week old calves was associated with decreased average daily gain (ADG) in the first 8 weeks of life (n = 744). In weaned calves (n = 74) increased activity (increase in steps and decrease in lying), standing at the bunk not eating, and lying far from other calves in the first 3 days post-weaning were associated with decreased post-weaning weight gain. For objective 2, separating social mixing from movement to a novel environment, and administering prophylactic antibiotics to calves at high risk of disease, were investigated. Both mixing and movement to a novel environment increased activity levels in newly weaned dairy calves (n = 64). When calves were mixed prior to movement to a novel environment they had a smaller increase in activity compared to calves that were simultaneously mixed and moved. No differences in weight gain or calf starter intake were observed. Administration of a prophylactic antibiotic, tulathromycin, to 3 day old calves upon arrival at a heifer raising facility (n = 788) and 8 week old calves at first movement to group housing (n = 1,392 ) was found to reduce diarrhea and otitis media, and BRD, respectively. Objective 3 was addressed by monitoring calves that received tulathromycin at 8 weeks of age to determine the long-term impacts of BRD. Bovine Respiratory Disease complex was associated with decreased growth to 9 months of age, decreased survival to first calving, increased risk of dystocia and a greater age at first calving. / Natural Sciences and Engineering Research Council of Canada & Pfizer Animal Health

In vitro embryo production (IVP) has been successfully used for infertility treatment, farm animal breeding and preservation of endangered species. Embryo culture media and its composition play an important role in the developmental competency of in vitro produced embryos. To optimize IVP it is important to understand the physiology of the in vivo embryo medium. Previously, we confirmed the presence of thyroid hormones (THs) in the bovine reproductive tract and their beneficial effect on embryo quality in vitro. The aim of this study was to further investigate the developmental effect and mechanisms behind THs function in bovine early embryos by supplementing IVP media with 50ng/ml T3 and T4. In vitro embryo culture (IVC) media fortification with THs significantly improved blastocyst and hatching rates, which was observed in both fast and slow cleaving embryos. THs treatment significantly skewed male/female ratio toward femaleness (43% vs. 57%). Only %60 of supplemented THs was bioavailable in the IVC media. Gene microarray and blastocyst genes expression profile analysis showed that THs supplementation altered mRNA expression profile in blastocysts. 1,234 genes were expressed differentially in the treated embryos and these differences were statistically significant (>1.5 fold at p < 0.05); these findings were confirmed by qPCR. TH-related genes, including THs receptor (TRs) mRNA and deiodinases (DIOs), were expressed in the gene array data of both treated and control groups. TR mRNA was expressed in all stages of early embryo development (EED) and the expression was not inducible by THs. This finding was consistent in both gene array and qPCR. Suppression of embryo gene transcription by α-amanitin resulted in a significantly higher level of TR mRNA from 2-cell to 16-cell treated and control embryos. TR protein was expressed in both treated and control blastocysts but, differentially located and distributed in response to THs in the blastocysts. This study highlights the importance of THs in EED and therefore the need to include these factors in culture media. Furthermore, this study has better characterized THs effects and identified possible regulatory roles of these hormones in EED. Further investigation into embryo competency and pregnancy outcome can provide more details. / Canada Research Chair(CRC), EmbryoGene, Ontario Graduate Scholarship(OGS) and Agriculture and Agrifood Canada.

In dairy cattle, treatment with exogenous growth hormone (GH) affects growth and function of mammary gland. The actions of GH are mediated via interaction with GH receptors (GHR). The first step in signal transduction is homodimerization of two GHR molecules by GH. This step is critical since mutation in either GH or GHR can block dimerization and thus target cell activation. However, association between milk related traits and combination of GH and GHR variations are not known. Accordingly, DNA genotypes in the GH and GHR genes were investigated for association with milk, fat and protein lactation yields in Holsteins. The marker data were obtained on 873 progeny tested bulls by using PCR-RFLP and PCR-SSCP analysis. There were five markers in GH and three in GHR. Estimated breeding values (EBVs) were obtained from Canadian Dairy Network for milk, fat, and protein lactation yields for the 873 genotyped bulls. / There was significant difference among GH6.1 alleles (C-to-G transversion at position 2141) for the milk yield (P < 0.05) and protein yield (p < 0.05). There were significant differences in GHR AluI (A-to-T transversion at -1182) for milk (p < 0.05) and fat (p < 0.05), and GHR StuI (C-to-T transversion at -232) for fat (p < 0.0001) and protein (p < 0.05). Allele frequencies for GH6.1 (C), GHR AluI (A) and GHR StuI (C) alleles in bulls genotyped were 0.95, 0.63 and 0.95, respectively. Bulls with GH6.1 (C/G) genotype had higher milk EBV (p < 0.05) compared to C/C bulls. Bulls with GHR AluI (A/A) genotype had higher milk EBV (p < 0.01) and fat EBVs (p < 0.05). Bulls with StuI (C/C) genotype had higher fat EBV (p < 0.0001) and protein EBV (p < 0.05) compared to StuI (C/T). This study indicates that the combination of GH and GHR markers could serve as a tool to aid in selection for improving milk, fat, and protein production.

The production of gelatine at Gelita N.Z. Ltd. is a time consuming process. The time limiting step in the process is the pre-treatment of the collagen tissue of the raw material in a lime/sodium sulfide solution. The liming solution breaks down the collagen in the tissue to gelatine. This is a necessary step prior to the extraction of gelatine from the hide pieces. The current liming process takes nearly 50 days to complete. Methods were investigated to increase the rate of penetration of the chemicals into the bovine hide raw material. An increase in the penetration of the liming solutions would lead to shorter processing times for this step in the process. The methods that were investigated were temperature controlled mixing, fluidization of the hide pieces and the use of ultrasound. Of all the methods tested, the fluidization of the hide pieces gave the best results. The pretreatment time of the hide pieces was reduced 9 days with this technique. Methods were also investigated to monitor the levels of conditioning in the raw material An accurate technique to measure hide conditioning was important to pilot plant trials. This helped determine how well any of the trail methods increased the penetration of chemicals into the hide pieces. The use of an ultraviolet dye proved an effective method of measuring conditioning for all the pilot plant trials. The level of chemical penetration was monitored by assessing the penetration of the UV dye. The penetration of the UV dye could be quantified by using imaging software. A possible method of monitoring conditioning in full-scale production was tested. It was determined that the glycosaminoglycans and soluble collagen released into the liming solution could be accurately measured, and related to the overall conditioning of the raw material.

Infection data were obtained monthly from June, 1999 to September, 2000 at the University ofKentucky dairy. Quarter foremilk samples were collected for bacteriological determination andsomatic cell counts (SCC). The Livestock Stress Index (LSI) estimated heat stress and is calculatedby combination of temperature and humidity. For uninfected quarters the geometric mean SCC was29,000 cells/ml. For infected quarters the geometric mean SCC was 213,000 cells/ml. Coagulasenegativestaphylococci (CNS) infections comprised 61 percent of the total infected quarters with ageometric mean SCC of 155,000 cells/ml. Staphylococcus aureus infected quarters had a geometricmean SCC of 680,000 cells/ml. There were no significant correlations between log SCC and LSIwhen looking at the total sample period. However, evaluating October, 1999 through September,2000, significant correlations were found for LSI and log SCC of uninfected quarters (P andlt; 0.05) and`infected quarters (P andlt; 0.0001). All correlation coefficients were less than 0.12. The results suggest nomarked changes in SCC were observed in uninfected quarters during hot summer weather. Hotsummer weather may have a minor impact on SCC in infected quarters, but the effect is variable.Thus, infection status of the mammary gland, not heat stress, is the major factor determining SCC.

Our objective was to know how the hepatic transcriptome expression of growing beef (Angus-cross) heifers (0.5 kg gain/day) was affected by the feeding of different sources of dietary (3 mg/day) Se supplements: inorganic Se (ISe, sodium selenite), organic (OSe, Sel-Plex®), or a blend (1.5 mg:1.5 mg) of ISe:OSe (Mix), compared to the adequate but non-Se supplemented “Control”. The biopsied hepatic tissues of these four groups heifers collected at day 168 (when liver Se assimilation had stabilized) after supplements of Se, was subjected to the microarray analysis to assess Se treatment effects. The results suggest that there were clear differences in the hepatic gene expression profile of the four Se treatment groups. 139 significantly treatment-induced differentially expressed transcripts were selected. Among them: 1) the gene expression profiles of Control and OSe appeared to be more similar than Control and ISe, 2) eight distinct gene expression patterns among treatments were identified and each of them indicates affected biofunctions and networks, 3) they were grouped as the expression profile relative to Control, there were solely and commonly affected transcripts for four Se treatments and they indicated different biofunctions, 4) of them, three microRNAs were identified and their predicated mRNA targets showed different biofunctions.

Endophyte-infected tall fescue produces many ergot alkaloids, which have been shown to be vasoconstrictive in various vessel types of bovine. On the other hand, substantial evidence has been reported on the vasodilative effects of formononetin and biochanin A in different vessel types in humans and rats. So, a study was conducted using mesenteric vasculature collected from heifers shortly after slaughter. After 2-h incubation with formononetin (F), biochanin A (B), or an ergovaline-containing tall fescue seed extract (EXT) and their combinations, vessels were mounted in a multi-myograph to determine their ergotamine-induced contractility. Results indicated that F and B at 1 × 10-6 M and their combination did not impact the contractile response to ergotamine in mesenteric vasculature. The pre-myograph incubation of mesenteric vasculature with EXT altered the contractile response manner to ergotamine. However, at higher concentration, F and B may alleviate the reduction of vasoconstriction caused by prior exposure to EXT. To our knowledge, this study was the first to investigate the interaction of ergot alkaloids and isoflavones on in vitro bovine mesenteric vasculature. However, further investigations are necessary to understand the mechanism behind the interaction of ergot alkaloids and isoflavones on vasoactivity.

La paratuberculose bovine, ou maladie de Johne, est une maladie inflammatoire intestinale chronique provoquant d’importantes pertes économiques chez les producteurs de ruminants du monde entier. Que ce soit chez la vache laitière ou de boucherie, ces pertes sont causées majoritairement par une diminution de la capacité de reproduction, la baisse de production laitière et l’amaigrissement des vaches qui perdent ainsi beaucoup de valeur à l’abattage, en plus d’être sujettes à une réforme précoce. Outre les pertes économiques, le potentiel de transmission à l’humain est un facteur non négligeable en plus d’un risque de contamination de la chaîne alimentaire. Cette maladie est causée par une bactérie intracellulaire obligatoire nommée Mycobacterium avium subspecies paratuberculosis (MAP). II n’existe actuellement aucune stratégie efficace pour combattre l’infection chez les animaux atteints. L’évolution lente de la maladie fait en sorte que les signes cliniques apparaissent tardivement, soit plusieurs années (4 à 7 ans) après l’infection initiale. Au cours de cette progression, les animaux infectés commencent à excréter le pathogène dans leur environnement. Les animaux atteints deviennent infectieux et peuvent contaminer d’autres congénères, ainsi que leur propre veau. Afin de permettre aux producteurs d’éliminer les vaches atteintes avant qu’elles n’atteignent ce stade, il s’avère important d’établir un diagnostic précoce. Actuellement, ce n’est qu’en phase sous-clinique avancée que les tests diagnostiques sont plus sensibles, soit 2 à 3 ans après le début des excrétions fécales chez les animaux infectés. L'incompréhension du manque de sensibilité des tests de dépistage et de l'évolution de cette maladie justifient les efforts de recherche dans ce domaine en vue de mieux comprendre les réponses immunitaires impliquées dans cette maladie. En effet, une meilleure connaissance des processus d’inflammation chronique pourrait aider à développer des outils diagnostiques complémentaires. Nos résultats suggèrent une dérégulation de la réponse immunitaire. Ainsi, en étudiant les composantes et caractéristiques du sang provenant de vaches infectées, il nous a été possible d’observer que les niveaux de cytokines plasmatiques telles l’interleukine 17 et l'ostéopontine se trouvent sécrétées à différents niveaux chez les vaches atteintes de paratuberculose bovine. De plus, l'analyse de la capacité de leur sérum à soutenir efficacement la prolifération des cellules mononucléées du sang périphérique révèle que le sérum de vaches infectées interfère pour atténuer la prolifération cellulaire. II semble qu’un constituant du sérum provoque une diminution de la réponse immunitaire chez les vaches malades. Les résultats offrnt une appréciation des dérèglements immunitaires provoqués par la paratuberculose bovine.

The overall objective of this thesis is to provide an enhanced understanding of the epidemiology of Mycobacterium bovis in the Greater Riding Mountain Ecosystem (GRME) and provide a scientific basis for disease management from a systems perspective now and into the future. M. bovis prevalence has been consistently higher in elk compared to white-tailed deer, and higher within a defined Core area compared to areas outside. Prevalence in both species declined significantly between 2003 and 2013. Only one infected elk was detected in 2013; the last infected white-tailed deer was detected in 2009 and the last infected cattle herd was detected in 2008. Parallel interpretation of three blood-based assays resulted in effective selective culling of elk within Riding Mountain National Park (RMNP) with predictive value negative of 100%. A lymphocyte stimulation test (LST) was the most sensitive single blood-based assay, but was difficult to perform under field conditions. Combinations of humoral antibody tests and cell-mediated tests performed better than any single test, likely detecting the broad spectrum of host pathology present. Seven of 14 risk factors were identified for wild cervids testing culture positive with the three being most strongly associated with culture positivity being geographical location (within core area), elk density and year category (sampling phase). Age, sex, and surveillance method were also significant factors, but species was not. A rapid decline in elk density in combination with fencing of hay storage yard and non-selective culling were likely key factors resulting in the M. bovis prevalence decline observed in elk, and an overall decline in prevalence from 1997 for both species. Elk were the primary reservoir species in this episystem, but are now considered a spillover host, while white-tailed deer have always been a spillover host due to lower densities and shorter life expectancy. Very limited strain diversity exists within the GRME with one spoligotype restricted to cattle and associated with a limited outbreak in five herds in the early 1990’s, and three other shared strains between cattle and wildlife. A single monomorphic type was present in white-tailed deer. Significant spatial overlap of wildlife and cattle isolates delineated a core area where management activities are now focused. The relative simplicity of this episystem has allowed significant progress on control and management to be achieved, despite being located within a national park. Wildlife surveillance will need to continue until at least 2022 in order to achieve a 95% probability of freedom using three different surveillance streams. Latent cases are likely to be extremely rare in future and unlikely to result in ongoing transmission as the factors that created this wildlife reservoir no longer exist. Wild cervids should not be considered ideal maintenance hosts for M. bovis in North America but rather facultative hosts; acting either as a reservoir or spillover host dependent on regional/local density and presence/absence of baiting and feeding.