Browsing by Author "Kastelic, John"

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    Assessment and Impacts of Newborn Beef Calf Vigour
    (2016) Homerosky, Elizabeth Rose; Kastelic, John; Windeyer, Claire; Timsit, Edouard; Pajor, Edmond
    Modified APGAR scores, intended to identify compromised calves with reduced vigour, yield inconsistent results and are not widely adopted. Data were collected from 77 newborn beef calves to determine calving characteristics and clinical examination parameters associated with abnormal blood parameters and a calf’s ability to consume colostrum by 4 h after birth. Calves born to primiparous dams, with increased calving difficulty, a weak suckle reflex, or incomplete tongue withdrawal, had decreased blood pH and increased L-lactate at 10 min after birth (P<0.05). Calves with a weak suckle reflex were 41.6 times more likely to fail to consume colostrum by 4 h compared to calves with a strong suckle reflex (P<0.0001). Calves that failed to consume colostrum by 4 h were 2.8 times more likely to be treated prior to weaning (P=0.03). In conclusion, good newborn beef calf vigour is a vital survival characteristic that helps ensure timely colostrum consumption, contributing to long-term health.
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    Conceptus-derived Fibrinogen and its Implication in Equine Pregnancy
    (2017) Macedo da Silva, Alysson; Klein, Claudia; Wynne-Edwards, Katherine; Kastelic, John; MacPhee, Daniel
    The equine conceptus presents an extensive mobile stage from days 9 to 16 after ovulation, during which it becomes fixed to one of the uterine horns. Throughout mobility, the conceptus secretes fibrinogen (an integrin-binding ECM). We hypothesized that conceptus-derived fibrinogen is converted into fibrin and aids in fixation via integrin receptors. We determined that RGD-binding integrins are expressed in endometrial and embryonic/fetal cells and interact with fibrinogen. Moreover, endometrial and embryonic cells presented the machinery to convert fibrinogen into fibrin and maintain the fibrin network. Overall, we demonstrated that conceptus-derived fibrinogen is likely converted to fibrin at the embryo-maternal interface and mediates cell adhesion via RGD-binding integrins.
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    Consequences of Testicular Heat Stress and Potential Amelioration Strategies
    (2023-01-12) Mohamed, Abdallah Mohamed Shahat; Kastelic, John; Kovalchuk, Igor; Pajor, Edmond; Pearson, Jennifer; Thundathil, Jacob; de Graaf, Simon; Honaramooz, Ali
    Heat stress (HS) is a worldwide problem due to temperature elevations associated with global warming. Monitoring temperature changes in testes and scrotum over time is important to understand thermoregulatory capacity of testes and scrotum. Temperature data loggers (DLs) are reliable devices that can be implanted in scrotal subcutaneous tissues to serially record intrascrotal temperature without altering animal behavior. Testicular HS causes a variety of outcomes, depending on the degree and duration of testicular heating. Some effects of testicular HS on testicular tissues, blood flow and sperm quality and attempts to prevent them, by treating animals or semen extender, have been reported. The overall objective of this study was to investigate impacts of HS on sperm quality and use various ameliorative strategies to mitigate these detrimental effects, using bull and ram models. We validated data loggers as a reliable, less invasive and serial method to measure intrascrotal temperature. Scrotal subcutaneous temperature was significantly increased by scrotal insulation or whole-body heating, but not by scrotal neck insulation; however, all three heat-stress models decreased sperm motility and morphology in bulls and rams. In addition, our hypothesis that melatonin or L-arginine improve quality of frozen-thawed sperm from HS rams was supported; 1 mM of either gave best results, except 0.5 mM minimized DNA Fragmentation Index (DFI%). Moreover, during hot weather, bulls voluntarily accessed shade, significantly lowering scrotal subcutaneous temperatures and improving sperm quality. In rams exposed to testicular HS, slow-release melatonin significantly improved testicular blood flow, protected sperm motility and morphology, and lessened HS-induced reductions in post-thaw sperm quality. Therefore, melatonin has potential for mitigating effects of testicular HS under field conditions.
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    Distribution of Staphylococcus non-aureus isolated from bovine milk in Canadian herds
    (2016) Condas, Larissa; Barkema, Herman; De Buck, Jeroen; Liljebjelke, Karen; Kastelic, John; Middleton, John; De Vliegher, Sarne; Armstrong, Glen
    The Staphylococci non-aureus (SNA) species are among the most prevalent isolated from bovine milk. However, the role of each species within the SNA group still needs to be fully understood. Knowing which SNA species are most common in bovine intramammary infections (IMI), as well as their epidemiology, is essential to the improvement of udder health on dairy farms worldwide. This thesis is comprised of two studies on the epidemiology of SNA species in bovine milk, and used molecular methods to identify of isolates obtained from the Canadian Bovine Mastitis and Milk Quality Research Network. The first study focused on the prevalence of SNA species on Canadian dairy farms and potential associations of SNA positive mammary quarters with bulk milk somatic cell count (BMSCC), barn type, parity, month of lactation and quarter location. Overall SNA represented 9% of the isolates from culture positive mammary quarters and the most common species were S. chromogenes, S. simulans, S. xylosus, S. haemolyticus, and S. epidermidis. Province and barn type were associated with SNA species distribution; Albertan bedded-packs were mostly affected by S. chromogenes, Maritimes free-stall herds by S. epidermidis, and Ontario and Quebec tie-stalls by S. xylosus. Staphylococcus arlettae, S. cohnii, and S. gallinarum were isolated from quarters of herds with high BMSCC. Fresh heifers and cows in later lactation were most frequently infected by S. chromogenes. The second study focused on the distribution of the same species in SNA positive-quarters according to udder inflammation status, classified according to low and high SCC and clinical mastitis. Average somatic cell count (SCC) for the SNA as a group was 70,000 cells/mL, driven mostly by S. chromogenes, S. haemolyticus, S. xylosus and S. epidermidis. Species-specific prevalence of SNA-positive quarters was higher in high (≥ 200,000 cells/mL) than in low SCC (< 200,000 cells/mL) samples for the 11 most frequently isolated SNA species. Staphylococcus sciuri was more frequently isolated from clinical mastitis samples. Considering SNA as a group will misrepresent the role of individual species on farms. Ultimately, adopting molecular identification of SNA species along with future research in species-specific risk factors are necessary to fully elucidate the importance of of the different SNA species on udder health and possible species-specific interventions.
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    Enhancing Antimicrobial Stewardship On Dairy Farms With A Focus On Selective Treatment Of Clinical Mastitis
    (2024-01-16) De Jong, Ellen; Barkema, Herman W.; Orsel, Karin; Kelton, David; Kastelic, John; Sanchez, Javier
    Clinical mastitis (CM) treatment decisions have been the focus of antimicrobial stewardship in the dairy sector, as CM and antimicrobial dry cow treatments account for the majority of antimicrobials used on farms. To improve on-farm antimicrobial stewardship, a selective treatment approach of CM is explored, centering around milk culture-guided decisions. Detailed principles of selective CM treatment and an evidence-based protocol are presented in Chapter 2, alongside an overview of expected cow and farm impacts, impact of proportion of Gram-negative cases on expected reduction in antimicrobial use, adoption rates across the globe, and knowledge and technology gaps. A systematic review and meta-analysis is presented in Chapter 3, evidencing that a selective CM treatment protocol can be adopted without adversely influencing bacteriological and clinical cure, somatic cell count, milk yield, and incidence of recurrence or culling. Chapter 4 presents survey results of 142 farms detailing adoption of various CM protocols among Canadian dairy farmers, demonstrating an association between increased adoption of selective CM protocols and low average cow SCC, as well as a distinction between 3 groups of farmers with similar relative importance of decision factors. Delving further into CM decision-making, Chapter 5 presents considerations of Western Canadian dairy farmers at each decision step from identification of CM to treatment termination, as well as 3 overarching themes impacting each step: Personal attributes, Inter-actor dynamics, and Moving beyond protocols. Chapter 6 describes 4 themes related to perceptions on mastitis-related antimicrobial use: Antibiotic use paradox: Perception vs. reality; Low disease incidence is a badge of honor; In good hands: Veterinarians as safeguards; and “It takes a village to make a change”, alongside 10 proposed interventions designed using the Behavior Change Wheel to mitigate voiced barriers and appeal to facilitators towards milk-culture guided decisions. To advance this research future efforts should be focused on improving selection of CM cases to exclude antimicrobial treatment, discouraging inadequate mastitis-related antimicrobial stewardship practices, enhancing quality and accessibility of milk diagnostic tests, and stimulating and monitoring uptake of selective CM protocols.
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    Nutritional Modulation of Reproductive Potential in Dairy Bulls
    (2016) Dance, Alysha; Thundathil, Jacob; Kastelic, John; Dobrinski, Ina; Klein, Claudia; Van Der Hoorn, Franciscus; Rancourt, Derrick; Sutovsky, Peter
    Holstein bull calves often reach AI centers in suboptimal body condition. Early-life nutrition is reported to increase reproductive performance in beef bulls. The general aim of this thesis was to determine effects of early-life nutrition on reproductive performance of Holstein bulls. We hypothesized that Holstein bull calves on high-nutrition diets during early-life will have larger testes, greater sperm production, and be younger at puberty than those on low-nutrition diets. We determined that bulls fed the high-nutrition diet from 2 to 31 wk were younger at puberty, had larger testes and had higher concentrations of circulating IGF-I than low-nutrition bulls. Furthermore, early-life nutritional modulation did not alter semen quality. The high-nutrition bulls had more proliferating and differentiating Sertoli cells earlier in life than low-nutrition bulls and IGF-I promoted proliferation of bovine Sertoli cells in culture. Overall we demonstrated that IGF-I has important roles in bovine reproduction and we identified key periods during bull development where it appeared that nutritional modulation affected testes development. Therefore, nutritional modulation can be recommended as a management tool to improve reproductive potential of AI bulls. In addition, we inferred that nutritional modulation may serve as a model for studying mechanisms controlling reproductive development in bulls.
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    Ouabain-induced activation of Phospholipase C zeta and its contributions to bovine sperm capacitation
    (2020-10-15) Unnikrishnan, Veena; Thundathil, Jacob; Kastelic, John; Rolian, Campbell
    The objective was to investigate involvement of testis-specific isoform of Na+/K+-ATPase ?4 (ATP1A4) in Phospholipase C zeta (PLC ?) activation during sperm capacitation and contributions of PLC ? activity to the capacitation process. Immunoprecipitation studies were done to confirm the interaction of PLC ? with ATP1A4 and to determine tyrosine phosphorylation of PLC ? during capacitation. Contributions of activated PLC ? to capacitation process were evaluated by determining phosphotyrosine content of sperm proteins (Immunoblotting), proportion of sperm acquiring hyperactivated motility (Computer-Assisted Sperm Analysis) and quantifying filamentous actin (F-actin; Flow cytometry analysis) content. Our results demonstrated that capacitation conditions promoted interaction of ATP1A4 with PLC ?, resulting in tyrosine phosphorylation of PLC ?. Incubation of sperm under capacitation conditions upregulated PLC-mediated biochemical modifications (hyperactive motility, tyrosine phosphoprotein content and increased F-actin content), suggesting that capacitation enhanced PLC activity. We inferred that interaction of ATP1A4 with PLC ? induces tyrosine phosphorylation of PLC ?, enhancing its activity and upregulation of capacitation-associated biochemical events. A capacitation-associated increase in PLC ? activity may enable sperm to initiate oocyte activation immediately after oocyte penetration (during fertilization). Since failure of oocyte activation after sperm penetration is considered a major reason for fertilization failure, results of this study may have important implications for male factor infertility treatments, e.g. improving efficacy of intracytoplasmic sperm injection (ICSI).
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    Re-emergence of canine Leishmania infantum infection in mountain areas of Beijing
    (2023-03-30) Liu, Gang; Wu, Yuanheng; Wang, Lei; Liu, Yang; Huang, Wei; Li, Yifan; Gao, Mengbo; Kastelic, John; Barkema, Herman W.; Xia, Zhaofei; Jin, Yipeng
    Abstract Canine Leishmaniasis (CanL) is an endemic infectious disease in China, causing visceral Leishmaniasis (VL) and resulting in important public health problem. However, in the last 3 y, endemic trends have changed considerably and spatial–temporal aggregation areas have shifted from northwestern to central China. Although Beijing was an endemic area for CanL in the last century, this disease has not been reported in Beijing since control programs were implemented in the 1950s. In the present study, PCR and immunochromatographic (ICT) were used to estimate prevalence of Leishmania infection in domestic dogs living in Beijing, a VL re -emergencearea. In total, 4420 canine blood samples were collected at vet clinics in 14 districts of Beijing. Overall prevalence (percentage of dogs seropositive and/or PCR positive) of CanL infection in Beijing was 1.22% (54/4420). However, prevalence of CanL in the western mountain areas was 4.68% (45/961), significantly higher than that (0.26%, 9/3459) of the plains. In addition, multilocus sequence typing (MLST) of seven enzyme-coding genes was used to examine phylogenetic relationships of CanL strains. Forty-one Leishmania infantum isolates were well separated from the other strains and divided into five major clades (A to E) by MLST analysis. All clades were closely related to strains from Sichuan Province and Gansu Province. A phylogenetic tree, based on the MLST, revealed that L. infantum in Beijing was genetically related to strains from western endemic of Mountain type VL in China. In conclusion, CanL has re-emerged in Beijing, and almost 5% of dogs living in Beijing’s mountain areas were infected with L. infantum. The phylogenetic tree based on MLST effectively distinguished species of Leishmania and reflected geographical origins. Because dogs are considered a natural reservoir, comprehensive control measures including surveillance, phylogenetic analyses and management should be implemented to mitigate or eliminate Leishmaniasis.
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    Relaxin's Potential Implications in Early Pregnancy in Mares
    (2016) Schwinghamer, Rose Anna-Marie; Klein, Claudia; Yates, Robin; Thundathil, Jacob; Kastelic, John; Chenier, Tracey
    Relaxin is expressed at high levels from the conceptus during the first 16 d of pregnancy in mares. The overall objective was to determine the potential implications of relaxin in equine endometrium, and the expression of RLN, RXFP1, RXFP2, RXFP3 and RXFP4 in pregnant and non-pregnant equine endometrium as well as in the conceptus. The location of RXFP1 in pregnant endometrium was examined and effects of relaxin on inhibition of PGF2α were detailed. The hypothesis that relaxin inhibits endometrial release of PGF2α and is the maternal recognition of pregnancy factor in mares was tested. This hypothesis was rejected with the conclusion that whereas relaxin is important in equine pregnancy, it is not the maternal recognition of pregnancy factor.
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    Subtyping Virulence Genes of Pathogenic Escherichia coli Isolated from Beef Cattle and Clinical Cases in Alberta
    (2016) Ferreira Tostes, Renata; DeVinney, Rebekah; Stanford, Kimberly; Reuter, Tim; DeVinney, Rebekah; Stanford, Kimberly; Reuter, Tim; Kastelic, John; Gannon, Victor
    The objective of this study was to subtype virulence genes of pathogenic E. coli isolated from cattle and human clinical cases in western Canada. We identified a variety of virulence profiles among strains and most serogroups presented a dominant genotype. Many O157 and non-O157 isolates lacked stx genes; the absence was greater in non-O157 and O157:nonH7 than in O157:H7 strains. Overall, virulence profile of cattle isolates were very similar to those reported in clinical cases, although it was not possible to establish a clear relationship between strains’ genotype and season collected or place-of-origin. Monitoring stx (e.g. stx1a and stx2a) and eae (e.g. λ/γ1-eae) subtypes can be a valuable tool for risk assessment and prediction of disease outcome. Microbial contamination may occur throughout the food production chain. Therefore, monitoring pathogenic E. coli is crucial to ensure food safety across the farm-to-fork scope.
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    The Sodium Pump Regulates Sperm and Sertoli Cell Function
    (2016) Rajamanickam, Gayathri Devi; Thundathil, Jacob; van der Hoorn, Frans; Dobrinski, Ina; Kastelic, John; Sullivan, Robert; Vijayan, Mathilakth
    Abnormalities in sperm function at the submicroscopic level (not detectable during routine semen evaluation) influence bull fertility and therefore the efficiency of cattle production. New knowledge regarding the molecular basis of spermatogenesis and sperm function will enable us to develop evidence-based approaches for improving fertility. The overall aim of this thesis was to investigate role of Na/K-ATPase (the sodium pump) isoforms in sperm function, Sertoli cell function and male fertility. In fresh bovine sperm, I identified two distinct pools (raft and non-raft) of the testis-specific isoform of Na/K-ATPase (ATP1A4) in the plasma membrane. The raft pool of ATP1A4 interacted with caveolin-1 and EGFR, whereas the non-raft pool of ATP1A4 interacted with EGFR, Src and ERK1/2 in capacitated sperm. In addition, a comprehensive analysis revealed that the ATP1A4 interactome differed between raft and non-raft fractions of capacitated sperm. Specifically, ATP1A4 interacted and co-localised with plakoglobin (member of β-catenin family of proteins involved in cell adhesion) in the equatorial segment of capacitated sperm; this suggests a potential role for these proteins in sperm-oolemma fusion. During investigation of ATP1A4 involvement in lipid rafts, I determined that ATP1A4 content and activity were increased during capacitation, perhaps due to translation of ATP1A4 mRNA in mitochondrial or mitochondrial-type ribosomes. In frozen-thawed sperm, content and activity of ATP1A4 was greater in high- versus low-fertility bulls and significantly correlated with fertility. Additionally, ATP1A4-induced ROS, calcium, actin polymerization and tyrosine phosphorylation were also involved in regulating post-thaw sperm function in these bulls. My results also demonstrated that prepubertal rat Sertoli cells expressed ATP1A1 (the ubiquitous isoform of Na/K-ATPase) and that ATP1A1-ouabain interaction regulated formation (modulation of claudin 11 and connexin 43 expression) and function (transepithelial electric resistance) of Sertoli cell junctional complexes through Src-EGFR-ERK1/2- CREB pathway in a dose-dependent manner. Overall, results demonstrated that isoforms of Na/K-ATPase have unique roles in controlling several aspects of sperm and Sertoli cell physiology, acting through its well-established enzyme activity and signaling functions. Consequently, isoforms of Na/K-ATPase are potential candidates for reversible male contraception and a biomarker for male fertility.