Predictors of foaling outcomes in barren and maiden thoroughbred mares in South Africa

Population demographics and reproductive performance of Thoroughbred populations have been described, but the most recent assessment of the South African Thoroughbred population was reported two decades ago. Objectives of this study were to report demographic data for selected Thoroughbred breeding populations and to analyse selected mare-level variables in association with foaling outcomes, as predictors of reproductive performance. The National Horseracing Authority of Southern Africa's stud health scheme requires annual screening of Thoroughbred stallions, maiden and barren mares for venereal pathogens prior to breeding. In 2018 and 2019, 1 065 and 1 207 horses were sampled, respectively. Demographic data were sourced from laboratory sample submission forms that accompanied samples and supplemented by data gathered from the annual Thoroughbred foal identification programme. Univariate analysis of candidate predictors of successful foaling outcomes was performed followed by assessment in a multivariable model. Median ages of mares and stallions tested in 2018 and 2019 were nine and 11 years, respectively. Nearly twice the number of barren compared to maiden mares were tested in each year, and failure to conceive was the most common reported reason for classification as barren. Of mares tested in 2018 and 2019, 68.1% (95% CI 65.1-70.9) and 63.3% (95% CI 60.4-66.1), respectively, subsequently produced foals that were presented for identification. Mare age, rather than reproductive status, was a significant predictor of having a foal presented for identification. In conclusion, novel demographic data were described for South African Thoroughbred populations. Seasonal foaling rate as the selected measure of reproductive performance for sampled mares ranged from 63.3% to 68.1% and declined with increasing mare age.http://www.jsava.co.zaEquine Research CentreProduction Animal Studie

Development of real-time reverse transcription polymerase chain reaction assays to quantify insulin-like growth factor receptor and insulin receptor expression in equine tissue

The insulin-like growth factor system (insulin-like growth factor 1, insulin-like growth factor 2, insulin-like growth factor 1 receptor, insulin-like growth factor 2 receptor and six insulinlike growth factor-binding proteins) and insulin are essential to muscle metabolism and most aspects of male and female reproduction. Insulin-like growth factor and insulin play important roles in the regulation of cell growth, differentiation and the maintenance of cell differentiation in mammals. In order to better understand the local factors that regulate equine physiology, such as muscle metabolism and reproduction (e.g., germ cell development and fertilisation), real-time reverse transcription polymerase chain reaction assays for quantification of equine insulin-like growth factor 1 receptor and insulin receptor messenger ribonucleic acid were developed. The assays were sensitive: 192 copies/μL and 891 copies/μL for insulin-like growth factor 1 receptor, messenger ribonucleic acid and insulin receptor respectively (95% limit of detection), and efficient: 1.01 for the insulin-like growth factor 1 receptor assay and 0.95 for the insulin receptor assay. The assays had a broad linear range of detection (seven logs for insulinlike growth factor 1 receptor and six logs for insulin receptor). This allowed for analysis of very small amounts of messenger ribonucleic acid. Low concentrations of both insulin-like growth factor 1 receptor and insulin receptor messenger ribonucleic acid were detected in endometrium, lung and spleen samples, whilst high concentrations were detected in heart, muscle and kidney samples, this was most likely due to the high level of glucose metabolism and glucose utilisation by these tissues. The assays developed for insulin-like growth factor 1 receptor and insulin receptor messenger ribonucleic acid expression have been shown to work on equine tissue and will contribute to the understanding of insulin and insulin-like growth factor 1 receptor physiology in the horse.http://www.ojvr.orgam201

Polymerase chain reaction-based national surveillance programme to determine the distribution and prevalence of Taylorella equigenitalis in South African horses

REASONS FOR PERFORMING STUDY : The response to the first outbreak of contagious equine metritis in South Africa included pioneering a web-based platform to coordinate key aspects of a national, real-time polymerase chain reaction (qPCR)-based stallion screening programme to determine the distribution and prevalence of Taylorella equigenitalis in stallions and exposed mares. OBJECTIVES : To define the hypothesised pre-existing status of T. equigenitalis in the South African equine population and progression of the epidemiological investigation via the implementation of a molecular diagnostic-based surveillance programme. STUDY DESIGN : Retrospective case series. METHODS : Screening for T. equigenitalis was via a qPCR assay on genital swabs obtained from predilection sites in stallions and mares with subsequent confirmation using bacterial culture according to prescribed methods.Equine Research Centre, University of Pretoria, South Africa and the Department of Agriculture, Forestry and Fisheries, Republic of South Africa.http://onlinelibrary.wiley.com/journal/10.1001/(ISSN)2042-33062017-05-31hb2016Companion Animal Clinical StudiesEquine Research CentreProduction Animal Studie

Detection of equine herpesvirus-4 and physiological stress patterns in young Thoroughbreds consigned to a South African auction sale

BACKGROUND : The prevalence of equine herpesvirus types-1 and -4 (EHV-1 and -4) in South African Thoroughbreds at auction sales is currently undefined. Commingling of young Thoroughbreds from various populations together with physiological stress related to their transport and confinement at a sales complex, may be associated with shedding and transmission of EHV-1 and -4. This prospective cohort study sampled 90 young Thoroughbreds consigned from eight farms, originating from three provinces representative of the South African Thoroughbred breeding demographic to a sales complex. Nasal swabs for quantitative real-time polymerase chain reaction (qPCR) assay to detect EHV-1 and -4 nucleic acid and blood samples for enzyme-linked immunosorbent assay for EHV-1 and -4 antibodies were collected from all horses on arrival and departure. Additional nasal swabs for qPCR were obtained serially from those displaying pyrexia and, or nasal discharge. Daily faecal samples were used for determination of faecal glucocorticoid metabolite (FGM) concentrations as a measurement of physiological stress and these values were modelled to determine the factors best explaining FGM variability. RESULTS : EHV-4 nucleic acid was detected in 14.4 % and EHV-1 from none of the animals in the study population. Most (93.3 %) and very few (1.1 %) of this population showed antibodies indicating prior exposure to EHV-4 and EHV-1 respectively. Pyrexia and nasal discharge were poor predictors for detecting EHV-4 nucleic acid. The horses’ FGM concentrations increased following arrival before decreasing for most of the remaining study period including the auction process. Model averaging showed that variation in FGM concentrations was best explained by days post-arrival and transport duration. CONCLUSIONS : In this study population, sales consignment was associated with limited detection of EHV-4 nucleic acid in nasal secretions, with most showing prior exposure to EHV-4 and very few to EHV-1. The physiological stress response shown by most reflected the combination of stressors associated with transport and arrival and these are key areas for future investigation into management practices to enhance health and welfare of young Thoroughbreds during sales consignment.Racing South Africa (Pty) Ltd, the Equine Research Centre and Departments of Companion Animal Clinical Studies and Production Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, South Africa.http://www.biomedcentral.com/bmcvetresam201

Reversibility of the effects of GnRH-vaccination used to suppress reproductive function in mares

Reasons for performing study: Active immunisation against gonadotrophin-releasing hormone (GnRH) provides a reversible method for control of oestrous behaviour and fertility in mares. Previous reports failed to demonstrate the interval to resumption of cyclic ovarian activity after GnRH-vaccination. Hypothesis: Administration of the GnRH-vaccine ImprovacÒ1 in a large group of mares of various ages will result in effective, reliably reversible suppression of ovarian activity within a two-year period. Methods: The mares, subdivided into three age categories were vaccinated twice (with a 35 d interval) using ImprovacÒ1 and were monitored via blood samples until Day 720 after initial vaccination for serum progesterone concentration determination by radio-immune assay and anti-GnRH antibody titre by enzyme immuno-assay. Samples were collected until individuals resumed cyclic ovarian activity. Results: All mares showed suppression of cyclic ovarian activity (SPC <1 nmol/l) and 92.2% resumed cyclic activity at Day 720 with a mean interval = 417.8 d (SD = 23.19) and median = 344 d. A significant age effect (P=0.028) on the interval, but not on GnRH-AB titre response, was observed between the youngest (11 years) categories. Conclusions: Immunising adult mares of all ages with ImprovacÒ1 resulted in a reversible suppression of cyclic ovarian activity in most mares. An age effect, with the youngest mares showing a longer interval to reversibility was observed.The Equine Research Centre of the University of Pretoriahttp://www.evj.co.uk/journals/hb2013ab201

A PCR-based screening program to assess the prevalence of Taylorella equigenitalis in breeding stallions in South Africa

The first outbreak of Contagious Equine Metritis (CEM) due to Taylorella equigenitalis in South Africa was reported to the OIE in May 2011 subsequent to importation of a stallion, the index case. Two additional positive stallions were identified on an initial trace-back. The outbreak-response prompted determination of the national prevalence and distribution of CEM. A nation-wide PCR-based screening of all breeding stallions motivated by a previous outbreak report [1] was implemented via a mandatory CEM-negative clearance certificate prior to use for natural breeding or semen collection. Compliance from breeders was facilitated by developing a web-based system providing an easily-accessed, rapid and costeffective sampling, testing and reporting process on www.cemsa.co.za. A submission form, information, a breed-indexed list of stallions achieving CEM-clearance and a method for obtaining and submitting two sets of swabs (with an interval > 7d) from the external genitalia were accessible on the website. A duplex PCR was chosen as the assay method due to potential for submission of samples with minimal restrictions on transit time and temperature criteria and rapid, high throughput, cost-effi-ciency and reported sensitivity *1,2+. A clearance certificate was issued via the website after negative results from both sets of samples.http://www.journals.elsevier.com/journal-of-equine-veterinary-sciencehb2016Equine Research Centr

Multi-omics analyses reveal that HIV-1 alters CD4+ T cell immunometabolism to fuel virus replication

Individuals infected with human immunodeficiency virus type-1 (HIV-1) show metabolic alterations of CD4+ T cells through unclear mechanisms with undefined consequences. We analyzed the transcriptome of CD4+ T cells from patients with HIV-1 and revealed that the elevated oxidative phosphorylation (OXPHOS) pathway is associated with poor outcomes. Inhibition of OXPHOS by the US Food and Drug Administration–approved drug metformin, which targets mitochondrial respiratory chain complex-I, suppresses HIV-1 replication in human CD4+ T cells and humanized mice. In patients, HIV-1 peak viremia positively correlates with the expression of NLRX1, a mitochondrial innate immune receptor. Quantitative proteomics and metabolic analyses reveal that NLRX1 enhances OXPHOS and glycolysis during HIV-1-infection of CD4+ T cells to promote viral replication. At the mechanistic level, HIV infection induces the association of NLRX1 with the mitochondrial protein FASTKD5 to promote expression of mitochondrial respiratory complex components. This study uncovers the OXPHOS pathway in CD4+ T cells as a target for HIV-1 therapy

Track E Implementation Science, Health Systems and Economics

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138412/1/jia218443.pd