Browsing by Author "Janzen, Eugene"

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    Characterization of the hoof bacterial communities in feedlot cattle affected with digital dermatitis, foot rot or both using a surface swab technique
    (2024-01-22) Wong, Nicholas S. T.; Malmuthge, Nilusha; Gellatly, Désirée; Nordi, Wiolene M.; Alexander, Trevor W.; Ortega Polo, Rodrigo; Janzen, Eugene; Schwartzkopf-Genswein, Karen; Jelinski, Murray
    Abstract Background Lameness is defined as altered or abnormal gait due to dysfunction of the locomotor system, and is a health issue of feedlot cattle, having major economic, labour, and welfare implications. Digital dermatitis (DD—a lesion of the plantar surface of the foot) and foot rot (FR—affects the interdigital cleft) are common infectious causes of lameness in feedlots. These hoof lesions can occur alone or in combination (DD + FR) in the same hoof. A total of 208 hoof swabs were collected from three commercial feedlots located in southern Alberta. Every lesion sample was matched with a corresponding control skin sample taken from a healthy contralateral foot. Control skin samples were also collected from cattle with no lesion on any feet. Bacterial communities of three types of hoof lesions (DD, DD + FR, FR) and healthy skin were profiled using 16S amplicon sequencing. Results Alpha diversity analysis revealed a lower bacterial diversity on DD and FR lesions compared to control skin. Beta diversity analysis showed that bacterial communities of DD, FR, and DD + FR lesions were distinct from those of the control skin. While the impact of feedlot was minimal, lesion type contributed to 22% of the variation observed among bacterial communities (PERMANOVA-R = 0.22, P < 0.01). Compared to the corresponding control skin, there were 11, 12, and 3 differentially abundant (DA) bacterial genera in DD, DD + FR, and FR lesions, respectively. Conclusions The bacterial community description of a DD + FR lesion is a novel finding. Not only did lesions lead to altered bacterial communities when compared to healthy skin, but the composition of those communities also differed depending on the hoof lesion. The 16S amplicon sequencing of surface swabs has significant value as a research tool in separating different hoof lesions and can provide additional insights to the polybacterial etiology of DD and FR in feedlot cattle.
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    Identifying Genetic Factors of BSE Susceptibility
    (2021-09) Dudas, Sandor; Cross, James; Gilch, Sabine; Crowley, John; Janzen, Eugene
    Bovine spongiform encephalopathy (BSE) is a transmissible, neurologic disease of cattle that decimated the cattle industry in many countries when it was discovered to be zoonotic. This disease is caused by a unique pathogen believed to be entirely composed of a misfolded, degradation-resistant form of a host-encoded protein. No therapies or cure currently exist for BSE, and so understanding the pathogenesis and host genes involved in this process could guide work to find ways to prevent or treat this invariably fatal disease. To identify genes playing a role in BSE susceptibility in cattle, genetic analysis was carried out on cattle that were experimentally-infected with BSE and showed variable disease outcomes. Chapter 2 explores potential genetic reasons for an abnormal outcome following oral BSE challenge. This analysis found that breed composition contributes to BSE outcomes in these experimental animals as well as in Canadian BSE field case cattle. In Chapter 3, an in-depth single nucleotide polymorphism (SNP) chip was used to genotype more than 200 experimental BSE challenged cattle with variable disease outcomes. Several genes with the potential to impact cellular calcium levels were identified as contributing to BSE susceptibility. The results also indicated that relatedness of the animals and breed composition are playing a role in the disease status. With several genomic targets identified as important, the research in Chapter 4 explored these genomic regions with targeted next generation sequencing. This analysis flagged additional SNPs in or near genes that can potentially alter the expression of genes involved in BSE pathogenesis. Experimental BSE susceptibility appears to be polygenic, with several genes each contributing a small amount, and this seems to be linked to relatedness and breed. The genes identified are highly expressed in the central nervous system and play a role in the function, maintenance, and survival of cells critical to this tissue. Several genes are linked to intracellular calcium homeostasis, a critical process playing a role in prion and other protein misfolding, neurodegenerative diseases. Additional work to decipher the contribution of the host breed and the breed of the BSE inoculum is warranted to understand the observed breed effects.
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    Impact of Age and Duration of Maternal Separation on Processing Stress and Vaccine Responses in Pre-weaned Beef Calves
    (2022-06) Silas, Haley; Pajor, Edmond; Windeyer, Claire; Galezowski, Angelica; Janzen, Eugene
    Spring processing is a common practice in western Canadian cow-calf herds that involves separating calves from their dams and restraining the calves while they receive a combination of procedures that may include vaccination, castration, branding, and dehorning. Spring processing events are thought to be stressful for the calf; however, the impact of their age and the duration of maternal separation is not known. The first study (Chapter 2) assessed impacts of age and duration of maternal separation on stress experienced by calves at processing. It was found that four- and eight-week old calves had similar behavioural indicators of stress and cortisol concentrations after processing. Calves separated for five hours before processing were less active after processing than calves separated for one hour before processing. This decrease in activity in calves separated for longer could indicate they have become exhausted or acclimatized to their pen. The second study (Chapter 3) assessed the impact of age and stress on immunoglobulin G (IgG) and immunoglobulin M (IgM) antibody responses to intranasal vaccination with a modified live vaccine against bovine herpesvirus type 1 (BHV1), parainfluenza virus type 3 (PIV3), and bovine respiratory syncytial virus (BRSV; Inforce3®, Zoetis Inc., New Jersey, USA). In this study, BRSV, PIV3, and BHV1 IgG concentrations remained relatively similar from baseline to post-vaccination, while BRSV, PIV3, and BHV1 IgM concentrations increased during the same period. Furthermore, this increase was greater in eight-week old calves than four-week old calves, potentially because old calves were more responsive immunologically than the younger calves. Cortisol concentration proved to have minimal association with antibody concentrations after vaccination, with only some weak positive correlations between cortisol at certain timepoints and BRSV IgG or BHV1 IgG concentrations post-vaccination. Overall, there was no difference between vaccinated and unvaccinated calves, suggesting that maternally derived antibodies may have prevented a detectable humoral immune response to vaccination. To our knowledge, this study was the first to consider IgG and IgM immune responses to vaccination at industry-relevant processing ages.