Diagnosis and vaccination for Bovine Genital Campylobacteriosis in beef heifers

Bovine Genital Campylobacteriosis is characterized by early pregnancy loss and temporary infertility in cattle. The purpose of this project was to compare diagnostic approaches to detect Campylobacter fetus subsp. venerealis and evaluate the efficacy of vaccination for Bovine Genital Campylobacteriosis. This thesis describes the results of two studies that compared different sample preparation methods for bovine vaginal mucus for real-time PCR and assessed a commercial vaccine in preventing infection and reproductive loss. The first study compared real-time PCR utilizing different bovine vaginal mucus sample preparation techniques to direct culture. The magnetic bead based protocol demonstrated higher sensitivity (48.4%, P=0.02) and lower specificity (78.9%, P=0.01) than the heat lysis protocol which involved an additional dilution step (Sens=29.4%, Spec=88.2%), but did not differ from the heat lysis protocol without sample dilution (Sens=35.0%, P=0.16; Spec=81.1%, P=0.62). The sample preparation method, designed for bovine preputial samples (Chaban et al. 2012. Can J of Vet Res; 76: 166), did not work well for vaginal mucus. All modifications of that method and magnetic bead based extraction technique had low sensitivity compared to culture probably due to the biophysical properties of vaginal mucus, which could cause loss of targeted DNA during processing, or repeated sample freezing and thawing. Release of DNA directly from vaginal mucus by a modified heat lysis protocol with consequent real-time PCR could be a promising rapid screening approach after validating on fresh samples. The second study compared the risk of infection and reproductive failure in heifers, vaccinated with a commercial multivalent vaccine containing C. fetus antigen, to heifers vaccinated with a comparable product without C. fetus, that were exposed to infected bulls. There was no significant difference between groups either in risk of Campylobacter fetus subsp. venerealis isolation (P>0.17) or in the proportion of heifers that cultured positive at least once (P=0.42), as well as in the median number times of cultured positive samples (P=0.24) and the time to first cultured positive (P=0.67). There was no difference by treatment in the weekly proportions of heifers diagnosed pregnant by either ultrasound (P>0.31) or serum concentration of pragnancy specific protein B (P>0.31) during the study, as well as in the time to first pregnancy for heifers ever diagnosed as pregnant (P=0.30) and those that remained pregnant at the end of the study (P=0.70). Similarly, the difference was not detected by treatment in the proportion of animals, ever detected pregnant during the study (P=0.57) and in pregnancy loss rates (P=0.28). However, heifers that aborted were 4 times more likely to be cultured positive than those that did not abort (P=0.01). Heifers that were not pregnant at the end of the study cultured positive 1.5 times more often than pregnant animals in treatment group (P=0.04), while in control group such difference was 4 times (P=0.01). Heifers that were not pregnant at the end of the study did not differ by treatment in the number of times cultured positive (P=0.14). In this study, the mean concentrations of ELISA antibodies to C. fetus after vaccination were more than 2 times higher in treatment group than in control group (P<0.02), but vaccination did not significantly reduce infection or improve pregnancy in heifers when exposed to Cfv-infected bulls. Sample preparation technique is important for successful real-time PCR; release of DNA directly from a CVM sample by a modified heat lysis protocol was easy to perform and could be promising as a rapid screening approach for Bovine Genital Campylobacteriosis after validating on fresh samples. Vaccinating of heifers with a polyvalent commercial vaccine, containing Campylobacter fetus antigen, according to the label, did not significantly reduce infection rate or improve reproductive performance when they were naturally challenged

Isoenzyme characterization of trichomonad parasites

A review of the literature on the history of Trichomonas vaginalis and studies on differences among T. vaginalis strains was carried out. A need for the study of the characteristics that might help identification of trichomonads in general and T. vaginalis in particular was noted. Studies on isoenzyme variants revealed four enzymes that could be useful in distinguishing between different trichomonads and among different strains of T. vaginalis. These were lactate dehydrogenase, malate dehydrogenase, hexokinase and glucose phosphate isomerase. Using these four enzymes, it was possible to divide most strains of T. vaginalis into 5 groups. the isoenzyme results is discussed. It was possible to seek correlation between iso-enzyme differences and other biological properties such as concanavalin A-induced agglutination and generation time of the parasites; stroni correlation between these pro-perties and the previously divided group were found. Isoenzyme studies on flagellates isolated from faeces of monkey showed them to be very different from T. vaginalis; electron microscopy revealed that these organisms are probably a Trichomitus species. The results of isocnzyme and other studies on some unusual T. vaginalis strains are also discussed. Investigation into isolation, cloning and staining for light microscopy studies were also under-taken

Search for New Fertility Markers in Bull Sperm

Sperm are stored for extended periods of time in the epididymis, but upon ejaculation motility is increased and lifespan is decreased. After insemination, sperm must traverse the female barriers and undergo capacitation to complete fertilization; however, there are differences in fertility even among bulls that successfully pass a breeding soundness exam. For any potential marker of fertility, there must be variability expressed among animals. The series of studies in this dissertation had the objective 1) to evaluate differences between epididymal and ejaculated sperm and respective fluids proteins to understand increased longevity of epididymal sperm; 2) to evaluate the potential of dystroglycan (DAG1) and plasma serine protease inhibitor (SERPINA5) as fertility markers; and 3) to evaluate whether post in vitro capacitation changes in sperm could be used to estimate fertility differences between bulls. In summary, it was observed that 1) epididymal sperm was able to maintain viability longer than ejaculated sperm when cultured under the same conditions, also, sperm energy metabolism appears to be more glycolytic compared to sperm in the ejaculate, based on the greater number of proteins related to this pathway only present in epididymal samples. Sperm also has a greater number of antioxidants available in the epididymis that is likely to be maintaining reactive oxygen species (ROS) at low concentrations to inhibit premature sperm activation. This is supported by a greater mitochondrial membrane potential of epididymal sperm compared to ejaculated sperm and the fact that epididymal sperm was able to maintain viability longer than ejaculated when cultured under the same conditions. Then, it was observed that 2) DAG1 and SERPINA5 proteins, that are associated with cell to cell interactions, were localized on the bovine sperm head, also, SERPINA5 was localized on the sperm tail, and concentrations of DAG1 and SERPINA5 on the sperm head were correlated with each other (P = 0.01, r2 = 0.54), also, SERPINA5 was correlated with embryo cleavage rate (P = 0.04, r2 = 0.48), and the percentage of tail labeled for SERPINA5 was correlated with sperm viability (P = 0.05, r2 = 0.44); however, neither protein was associated with sire conception rate (SCR; i.e., field fertility). Thus, SERPINA5 may be related with sperm protection and/or oocyte fertilization while DAG1 may be related to sperm transport or formation of the sperm reservoir in the oviduct. Lastly, it was observed that 3) multiple analyses over time in capacitation media of viability, zinc signature 2, zinc signature 1 + 2, and dead CD9+ were able to estimate differences between low fertility bulls to high and intermediary fertility bulls. The inclusion of a viability, a zinc signature, or CD9 protein assay in artificial insemination (AI) studs’ quality control measurements may have the potential to predict bull fertility; however, a larger number of bulls with known fertility need to be evaluated to validate these results. In conclusion, more research is necessary to understand: 1) the role of the proteins only identified in epididymis and their role in increased sperm longevity; 2) the role of SERPINA5 and DAG1 in vivo; and 3) the potential of viability, zinc signature and CD9 protein analyses post sperm capacitation as predictors of bull fertility

Insights from Animal Reproduction

The chapters in this volume of "Insights from Animal Reproduction" address several, particular hot topics in the field of reproduction. The book begins with a comprehensive overview of the cryopreservation of sheep-produced embryos. The following chapter revises the assisted reproductive techniques available for South American wild mammals. Chapter 3 presents the technical procedures necessary to produce transgenic goats. Chapter 4 provides a comprehensive revision of the major molecular determinants of litter size in prolific species. Chapter 5 examines the germ cell determinant transmission, segregation, and function using the zebrafish as a model for germ cell specification in the embryo. Chapter 6 summarizes the current understanding of the molecular and cellular mechanisms regulating the early stages of folliculogenesis. Chapter 7 examines the sperm motility regulatory proteins as a tool to enhance sperm quality in cryopreservation processes. Chapter 8 discusses contemporary knowledge on the effects of extremely low frequency magnetic fields (ELF-MF) on male reproductive function in rodents. Chapter 9 highlights the importance of the cytogenetic evaluation in searching for causes of infertility of phenotypically normal animals, as well as individuals with an abnormal sex development. The last chapter provides evidence that other uterine diseases may be hidden behind the clinical diagnosis of pyometra that in some case may have a poor outcome

Faculty Day, 7 September 2017 : research overview

Oral presentations: Occurrence and characterisation of big seven Shiga toxin-producing Escherichia coli serotypes in healthy cattle from cow-calf operations in Gauteng and Northwest provinces, South Africa / Mainga A.O., Malahlela M., Tshuma T., Cenci Goga B.T., Karama M. -- Seroprevalence of leptospirosis in slaughtered animals in Gauteng Province abattoirs, South Africa / Dogonyaro B.B., Van Heerden H., Potts A.D., Lötter C., Katsande C., Fasina F.O., Adesiyun A.A. -- Interaction of Tritrichomonas foetus infection with the vaginal bacterial flora of heifers / Martins I.S., Swanevelder Z.H., Irons P.C. -- Prevalence of Clostridium difficile and Salmonella spp. in juvenile dogs affected with parvovirus enteritis / Botha W.J., Schoeman J.P., Marks S.L., Morley P.S., Whitehead Z., Annandale C.H. -- Artificial insemination trial with frozen-thawed semen on exogenous hormone induced oestrus in African lion (Panthera leo) / Callealta I., Luther, I., Ganswindt A., Scheepers G., Kasberg J., Lüders I., Kotze A., Mueller K. --Sir Arnold Theiler Memorial Lecture: "The Research Imperative" / Prof Robert Gilbert -- Seroprevalence and factors associated with Rift Valley fever in domestic ruminants in the Free State and Northern Cape provinces / Avenant A., Ngoshe Y.B., Rostal M., Cordel C., Paweska J.T., Karesh W.B., Thompson P.N. -- Seroprevalence and associated risk factors of West Nile Virus in equine populations in South Africa / Jeal R.E., Gummow B., Venter E.H. -- Evaluation of haemostatic changes in dogs with parvovirus enteritis before and after fluid resuscitation using thromboelastography / Whitehead Z., Goddard A., Pazzi P. -- Leopards and land use: using glucocorticoid metabolites to measure stress / Webster A.B., Burroughs R.E.J., Laver P.N., Ganswindt A. -- Could diclofenac’s toxicity in vultures have been predicted? / Hassan I.Z., Duncan N.M., Adawaren E.O., Naidoo V. -- Interesting research development showcase from Production Animal Studies / Bertschinger H.Poster presentations: 1. Effect of usage of antibiotics on virulence profiles of Escherichia coli in pig production / Abubakar R.H., Madoroba E., Fasina F.O. -- 2. Exploring next generation sequencing on the ION S5 as a basis for investigating the potential role of the CYP 2 gene family in the metabolism of diclofenac in Cape vulture (Gyps coprotheres) / Adawaren E.O., Naidoo V., Mukandiwa L., Suleman E., Du Plessis M. -- 3. PacBio Circular Consensus Sequencing uncovers the haemoparasite microbiome in South African wild and domestic felids / Bosman A.M., Gall C., Peasley A., Pazzi P., Penzhorn B., Wildung M., Oosthuizen M.C., Brayton K.A. -- 4. Methods for repeatable separation of the components of infertile and fertile Nile crocodile eggs for the determination of inorganic elemental constituents / Brown G.J., Forbes P.B.C., Myburgh J.G., Nöthling J.O. -- 5. Cardiopulmonary effects of anaesthesia maintained by propofol infusion versus isoflurane inhalation in cheetah (Acinonyx jubatus) / Buck R.K., Tordiffe A., Zeiler G.E. -- 6. A comparison between manual count, flow cytometry and qPCR as a means of determining Babesia rossi parasitaemia in naturally infected dogs / De Villiers L., Quan M., Troskie M., Fosgate G.T., Leisewitz A.L. -- 7. Preliminary assessment of seven under-investigated South African plants from the Myrtaceae family for activity against Bacillus anthracis Famuyide / I.M., Fasina F.O., Eloff J.N., McGaw L.J. -- 8. Evaluation of several tree species for activity against salmonella / Gado D.A., Ahmed A.S., Botha F.S., Ehlers M., McGaw L.J. -- 9. Shotgun genome sequence and population diversity of Mannheimia haemolytica isolates from sheep in South Africa / Gelaw A.K., Cutler S., Guthrie A., Fosgate G.T. -- 10. The pathology of the spleen in canine Babesia rossi infection / Henning A., Clift S.J., Leisewitz A. -- 11. The effect of preconditioning on the health and production of calves in a South African feedlot / Hentzen A.H.R., Thompson P.N., Holm D.E. -- 12. Towards a yellow tulp vaccine: preliminary studies exploiting the potential for cross-reactivity with related bufadienolides / Isa H.I., Ferreira A., Crafford J.E., Botha C.J. -- 13. Gross morphology and basic histological structure of the Apparatus lacrimalis of the ostrich (Struthio camelus) and emu (Dromaius novaehollandiae) / Kleyn E., Groenewald H.B., Soley J.T. -- Genetic variability of Anaplasma phagocytophilum strains circulating in wild rodents in Bushbuckridge, Mpumalanga, South Africa / Kolo A.O., Chaisi M.E., De Boni L., Collins N.E., Brayton K.A., Oosthuizen M.C. -- 15. Prevalence of brucellosis in slaughter animals in Gauteng province abattoirs, South Africa: food safety implications / Kolo F.B., Adesiyun A.A., Katsande C., Fasina F.O., Van Heerden H. -- 16. Effects of chemical and mechanical stimulation on laryngeal motion during anaesthetic induction with alfaxalone, thiopentone or propofol in healthy dogs / Labuscagne S., Zeiler G.E., Dzikiti T.B. -- 17. Phylogenetic analysis of 2015-2016 Nigerian highly pathogenic avian influenza (HPAI) H5N1 viruses / Laleye A.T., Joannis T.M., Shittu I.A., Meseko C.A., Zamperin G., Milani A., Zecchin B., Fusaro A., Monne I., Abolnik C. -- 18. Effect of climatological factors on the bulk milk somatic cell count on South African dairies / Lategan A., Nielen M., Vernooij H., Fosgate G.T., Van der Leek M. -- 19. Dietary supplementation of conjugated linoleic acids on sperm quality and freezability in bovines / Liman M.S., Cardoso C.L., Holm D.E., De Bruyn S., Gasparrini B., Franco V., Longobardi V., Esposito G. -- 20. Herd-level prevalence of bovine leukaemia virus infection and associated risk factors in commercial dairies in five provinces of South Africa / Maboe S.J., Gratwick W., Thompson P.N. -- 21. Prevalence of Salmonella spp. in slaughter cattle, the abattoir environment and meat sold at retail outlets in Gauteng province / Manqele A., Adesiyun A.A., Madoroba E., Onyeka L.O., Thompson P.N. -- 22. Magnetic resonance imaging of the muscle tendons in the carpal region of the southern white rhino (Ceratotherium simum simum) / Meusel E.G., Crole M.R., Marais J. -- 23. Investigation of antimicrobial, antioxidant, and anti-inflammatory activities of two Newtonia spp. with potential for alleviating infectious diarrhoea symptoms / Motlhatlego K.E., Njoya E.M., Abdalla M.A., Eloff J.N., McGaw L.J. -- 24. A comparative study of the infundibular epithelium in laying and moulting commercial hens / Mpango M.M., Madekurozwa M.-C. -- 25. Rift Valley fever, Congo fever and brucellosis: human seroprevalence and behavioural exposure in central South Africa (2015-2016) / Msimang V., Paweska J.T., Weyer J., Rossouw J., Jansen van Vuren P., Thompson P.N. -- 26. Aspects of plant variety protection (plant breeders’ rights), in relation to seed crops, that may impact on policy and legislative development in South Africa / Netnou-Nkoana N.C., McGaw L.J., Eloff J.N. -- 27. Ovarian dynamics and injection site reactions associated with immunocontraceptive zona pellucida (ZP) and GnRH vaccination of domestic horse mares (Equus caballus) / Nolan M.B., Bertschinger H.J., Schulman M.L. -- 28. Anti-inflammatory activity of selected southern African medicinal plants with possible application against parasitic nematode infections / Ondua M., Njoya E.M., Abdalla M.A., McGaw L.J. -- 29. Prevalence and characterization of Shiga toxin-producing Escherichia coli in beef carcasses and beef products in Gauteng province / Onyeka L.O., Adesiyun A.A., Madoroba E., Manqele A., Thompson P.N. -- 30. Mycobacterium bovis infection in cattle at the wildlife/livestock interface in northern KwaZulu-Natal province, South Africa / Sichewo P.R., Etter E., Michel A.L. -- 31. Vaccine matching: a different pathway to foot-and-mouth disease control / Sirdar M.M., Blignaut B., Heath L., Gummow B., Fosgate G.T. -- 32. Serum albumin level of donor cows as indicator of development competence of oocytes / Smuts M.P., De Bruyn S., Thompson P.N., Holm D.E. -- 33. The preventive and failure costs of mastitis in South Africa / Leenaerts L., Hogeveen H., Schlimmer N., Van der Leek M. -- 34. A survey of mastitis management practices used on South African dairies / Schlimmer N., Leenaerts L., Hogeveen H., Van der Leek M. -- 35. Adaptation of SAT1 and SAT2 foot-and-mouth disease virus in cattle and goats / Van der Merwe, D., Sirdar, M.M., Van Heerden, J., Heath, L., Fosgate, G.T., Blignaut, B. -- 36. Seroprevalence of Rift Valley fever virus in domestic and wild ruminants in far northern KwaZulu-Natal, South Africa / Van Loggerenberg C., Thompson P.N., Swanepoel R., Venter E.H. -- 37. Important trace element concentrations in ovine liver as determined by energy dispersive handheld X-ray fluorescence spectrometry / Van Loggerenberg D.E., Myburgh J.G., Laver P., Botha C.J. -- 38. Thromboelastographic platelet mapping findings in dogs with complicated Babesia rossi infection / Van Rooyen L.J., Hooijberg E.H., Schoeman J.P., Goddard, A. -- 39. Carnivore population dynamics on two reserves, comparable or not? / Wentzel J.M., Camacho G.C. , Bourn M., Fosgate G.T.Abstracts of the oral and poster presentations delivered at the 2017 Faculty Day held at the Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa.Organising Committee: Dr Rebone Moerane (Chairperson), Prof Vinny Naidoo, Prof Marinda Oosthuizen, Prof Geoffrey Fosgate, Dr Gerhard Steenkamp, Mr Chris Van Blerk, Ms Margaret Louw, Ms Daleen Anderson, Sr Ingrid de Goede, Ms Alet Wannenburg, Ms Maude da Cal, Ms Fransie Lottering, Ms Rene PerridgeScientific Committee: Prof Peter Thompson (Chairperson), Prof A Goddard, Prof John Soley, Prof Melvyn Quan, Dr Adrian TordiffeIncludes a list of scientific, peer-refereed articles, published in 2016, of which a member or student of the Faculty of Veterinary Science, University of Pretoria, was an authorWhitehead Scientific (Pty) Ltd ; Labotec ; Bayer HealthCare Animal Health ; DIAG ; Zeiss ; Sky Information Suppliers ; AXIM ; The Scientific Group ; Cipla Vet Animal Health ; Onderstepoort Biological Products ; MSD Animal Health ; Zoetis ; Wirsam Scientific & Precision Equipment (Pty) Ltd ; Inqaba biotecab201

The influence of superstimulation protocol on oocyte developmental competence in dairy cattle

Thesis (MScAgric)--Stellenbosch University, 2024.ENGLISH ABSTRACT: The increasing demand for dairy products globally, places increasing pressure on dairy producers to select animals for higher milk yield. In South Africa, market forces and the resulting economic pressure have resulted in a decline in the number of dairy producers, which necessitates that existing producers need to increase the average herd size and select dairy animals for a high milk yield, to remain sustainable in the South African dairy sector and to meet the ever-increasing demands of the consumer. The negative impact of selecting dairy animals for high milk yield is reflected in the decline in fertility of dairy animals, not only in South Africa, but globally. The purpose of this study was to evaluate the effects that age, lactation stage, and superstimulation program have on the fertility of Holstein dairy cows. The effect these factors have on fertility was assessed by looking at oocyte developmental competence in an in vitro embryo production system. The selection of the Holstein breed as donor animals, is based on the substantial representation of this dairy breed in the dairy industry. Twelve Holstein cows were selected as oocyte donors and allocated to three different age categories, i.e.3-4 years, 5-8 years, and 10-11 years; and according to stage of lactation, i.e. dry (non-lactating), early lactation (120 Days in milk). The donor animals were then randomly allocated into four different FSH-concentration superstimulation treatment groups (i.e. Control: 0 mg, Low: 150 mg, Medium: 180 mg, High: 240 mg). The superstimulation program and transvaginal oocyte retrieval (TVOR) were repeated every 28 Days, for four repetitions, to ensure that each donor was subjected to each treatment. In this study, the age of the donor and the FSH concentration had no significant effect on follicular wave response, oocyte developmental competence, or embryo yield in an in vitro embryo production system. Lactation stage, although not having a significant effect on follicular wave response, significantly influenced the number of embryos, with non-lactating cows producing 5.63 ± 0.76 embryos, compared to early-lactation cows (2.96 ± 0.53 embryos), and mid-lactation cows (1.97 ± 0.72 embryos). The findings from this study highlighted the impact of dairy cow nutrition on the quality of oocytes, which was more pronounced than the influence of cow age and FSH treatment. The high demand for nutrients in lactating animals disrupts the delicate physiological balance that is required to ensure oocyte developmental competence, in vivo as well as in vitro. The negative impact of lactation on oocyte developmental competence, and the partitioning of nutrients in favour of milk production at the cost of reproduction is clearly highlighted in this study.AFRIKAANSE OPSOMMING: Die toenemende aanvraag na melk en melk-produkte wêreldwyd, plaas suiwelprodusente onder druk om diere te selekteer vir hoër melkproduksie. In Suid-Afrika, het markkragte en ‘n verwante toenemende ekonomiese druk op suiwelprodusente tot ʼn afname in die aantal -produsente gelei, wat tot gevolg dat bestaande suiwelprodusente gedwing word om hulle kuddes te vergroot en diere te selekteer vir hoër melkproduksie, om ekonomies volhoubaar te bly en om aan die toenemende aanvraag vir suiwelprodukte te voldoen. Die benadering in die suiwelbedryf om diere met ʼn hoër melkproduksie te selekteer, het ʼn negatiewe invloed op melkbees vrugbaarheid in Suid-Afrika, sowel as in die res van die wêreld. Die doel van hierdie studie was om die effek van ouderdom, laktasie stadium en superstimulasie program op die vrugbaarheid van Holstein melkkoeie, te evalueer. Die effek wat die onderskeie faktore op vrugbaarheid het, is bepaal deur na oösiet ontwikkelingsvermoë in 'n in vitro embrio produksie program te kyk. Die keuse van die Holstein ras as skenkers is gebaseer op die aansienlike verteenwoordiging van hierdie beesras in die suiwelbedryf. Twaalf Holstein melkkoeie is as oösietskenkers geselekteer en in drie verskillende ouderdomskategorieë, d.i. 3-4 jaar, 5-8 jaar en 10-11 jaar en ook volgens stadium van laktasie, d.i. droog (nie- lakterend), vroeë laktasie (<120 dae in melk) en mid-laktasie (>120 dae in melk), ingedeel. Die skenkerdiere is toe ewekansig in vier verskillende FSH-konsentrasie superstimulerings-behandelingsgroepe verdeel (d.i. Kontrole: 0 mg, Laag: 150 mg, Medium: 180 mg, Hoog: 240 mg). Die superstimulasie program en transvaginale oösietherwinning (TVOR) is elke 28 dae, vir vier herhalings, herhaal om te verseker dat elke skenker aan elke behandeling onderwerp is. In hierdie studie het die ouderdom van die skenker en die FSH-konsentrasie geen betekenisvolle effek op follikulêre golfrespons, oösiet ontwikkelingsvermoë of aantal embrio’s in 'n in vitro embrio produksie program gehad nie. Laktasie stadium, hoewel dit nie 'n beduidende effek op follikulêre golfreaksie gehad het nie, het die aantal embrio's beduidend beïnvloed, met nie-lakterende koeie wat 5.63 ± 0.76 embrio's geproduseer het, in vergelyking met vroeë laktasie koeie (2.96 ± 0.53 embrio's), en mid-laktasie koeie (1,97 ± 0,72 embrio's). Die bevindinge van hierdie studie het die belang van melkkoei voeding op die kwaliteit van oösiete uitgelig, wat ‘n groter invloed as koei-ouderdom en FSH-behandeling, gehad het. Die hoë aanvraag na voedingstowwe in lakterende diere versteur die delikate fisiologiese balans wat oösiet ontwikkelingsvermoë beide op ‘n in vivo en in vitro vlak, sal verseker. Die negatiewe invloed van laktasie op oösiet ontwikkelingsvermoë en die verdeling van voedingstowwe ten gunste van melkproduksie, ten koste van reproduksie, word duidelik in hierdie studie uitgelig.Master

Viability of Tritrichomonas foetus Following the Freeze-Thaw Cycle Used for Freezing Bovine Semen

Although past research has proven the organism, Tritrichomonas foetus, can survive freezing technologies utilized in the 1950’s, it is unknown if it can survive freezing in liquid nitrogen, the current freezing media for bovine semen. Live organisms were identified after thawing in fiveof the twelve straws evaluated. Between 0.5 and 6 liveorganisms were identified in the samples taken from thesestraws. The number of live organisms within each of these 0.5 mL straws was estimated to be between 25 and 300 live organisms. The ability of T. foetus organisms to survivecurrent freeze-thaw techniques for bovine semen suggeststhat artificial insemination using semen from T. foetuspositive bulls poses a significant risk for spreading thispathogen to other cattle in breeding herds</p

Applied Reproductive Strategies in Beef Cattle

These proceedings summarize historical and current research on the physiological processes of the estrous cycle, procedures for synchronizing estrus and ovulation, and the proper application of these systems for artificial insemination. There is also a review of the biological and managerial factors that affect fertility in bulls and cows

Investigating the early interaction between Mycobacterium avium ssp paratuberculosis and the host using a bovine enteroid system

Mycobacterium avium ssp paratuberculosis (MAP) is the causative agent of Johne’s disease (JD), a chronic granulomatous enteritis of ruminant’s prevalent world-wide. Infection of calves occurs through the faecal oral route, typically in animals <6 months old. Animals are asymptomatic for 2-5 years before clinical signs begin to show, which typically present as emaciation and chronic diarrhoea. In the subclinical phase, animals will have decreased milk yield, increased susceptibility to other diseases and decreased feed conversion. This has a severe impact on the farming economy and animal welfare, as affected animals are often prematurely culled. Infected subclinical animals are extremely difficult to identify but can still act as a source of transmission for the rest of the herd by shedding MAP in their faeces. There is no treatment for JD, and the current diagnostic tests are ineffective. By investigating the initial interaction between MAP and the host at the intestinal lining, a greater understanding of MAP pathogenesis can be gained and better diagnostic and therapeutic targets can be identified. In this work, proteins expressed on the surface of MAP were assessed for their ability to aid attachment, invasion and intracellular survival in epithelial and phagocytic cells when expressed on the membrane of a non-invasive E. coli host strain. The proteins investigated were encoded by mammalian cell entry (mce) genes, mce1A, mce1D, mce3C and mce4A, which have been implicated in attachment and invasion of epithelial cells by other mycobacteria. Interestingly, E. coli expressing Mce1A had enhanced uptake by phagocytic cells and E. coli expressing Mce1D had enhanced attachment and invasion of epithelial cells, but neither protein conferred this phenotype in both eukaryotic cell types investigated. To identify key intestinal cell types involved in MAP pathogenesis, bovine intestinal organoids (enteroids) were assessed for their ability to model a MAP infection in a physiologically representative system. Baso-out 3D enteroids, apical-out 3D enteroids and 2D monolayers were created, and the cell types present were compared to bovine intestinal tissue samples using RT-PCR and immunofluorescence microscopy. The models contained the mature epithelial cell types of the intestine including goblet cells, enteroendocrine cells, Paneth cells and enterocytes. 3D baso-out enteroids and 2D monolayers also contained proliferative cells, but the 3D apical-out enteroids did not and so could not be maintained past 2 weeks of culture. The models were infected with two strains of MAP over the course of 72 hours, the reference strain K10, and a recent clinical isolate C49. MAP C49 was shown to be present in all three intestinal models in consistently higher numbers than MAP K10, quantified using qPCR of the genomic DNA. This indicates that MAP C49 was better able to infect these models than K10, which may suggest a loss of virulence in MAP K10. Overall, the data presented has increased our understanding of MAP pathogenesis by emphasising the need for multicellular models which accurately represent the pathogen target cell type/s in vivo and the confirmation of the role of two hypothetical MAP proteins in cellular interactions