The feral horses of Namibia : factors affecting the conversion from domesticated to a feral desert horse

Arbetet syftar till att undersöka de namibiska vildhästanas ursprung och vilka faktorer som bidragit till att de överlevt i Namibias öken i mer än 100 år. Vidare har även hästarnas behov av människan, populationens livsvillkor samt hur populationen vidare bör förvaltas undersökts. Trots att teorierna om hästarnas ursprung är många har genetiska studier visat att den ferala flocken av namibiska vildhästar härrör från domesticerade hästar av arab-typ, eventuellt med sitt ursprung från ett stuteri en gång drivet av Emil Kreplin. Genom historiens förlopp har hästarna utvecklats i ett isolerat område under hårt selektionstryck från miljön, såsom påverkan av perioder av torka, svält och predatorer. Detta i kombination med deras genetiska bakgrund anser jag vara det som gett dem deras ökenadapterade beteende och fysiologiska mekanismer. På grund av sin unika bakgrund har hästarna blivit en populär population att studera på hög nivå, men även ett attraktivt turistresemål som generar ekonomiska intäkter till Namibias turistindustri. Idag finns hästarna att beskåda i Naukluft Park i Namibia och besöks årligen av tusentals turister. De senaste fem åren har det område i Namibia som hästarna lever i utstått en svår period av torka, vilket medfört att naturliga vattenkällor torkat ut och vegetationen försvunnit. Då hästarna stängslats in av staket och öken kan de inte heller vandra ut från nationalparken. Torkan har, i kombination med att antalet hyenor uppförökats i parken, orsakat en drastisk nedgång av antalet hästar, vilket fått till följd att en ny genetisk flaskhals i populationen inte längre går att undvika. Då problemet diskuterats under lång tid av olika grupper i samhället har lösningen blivit mer eller mindre komplicerad. De namibiska vildhästarnas egen officiella organisation, Namibia Wild Horses Foundation, vill flytta hästarna till säker betesmark till dess att regnet återkommit och hästarna har möjlighet att klara sig själva igen. Organiserade grupper från turistindustrin vill istället flytta antingen hästarna eller hyenorna från området, då inträde av nya flockar av hyenor skulle vara lättare att kontrollera samt påverka turismen i lägre grad. Den ansvariga myndigheten Ministry of Environment and Tourism, står i limbo med ambitionen att fatta ett beslut som innebär det bästa för såväl hästarna som turistindustrin. Som en kortsiktig lösning har man stödutfodrat hästarna såväl som hyenorna för att minska predationstrycket, vilket gett en viss positiv effekt. Beslutsfattandet för vad som skall göras för att rädda hästarna har dock dragit ut på tiden till den grad att läget idag är kritiskt och att antalet hästar är nere på cirka 80 individer med inte ett enda överlevande föl på fem års tid. Den lösningen jag ser på problemet är att populationen av namibiska vildhästar behöver ett starkt stöd på myndighetsnivå för att ta sig ur denna svåra situation. Den behöver övervakas rent genetiskt och ha en god praktisk planering för den fortsatta överlevnaden. Flocken kommer också att behöva fortsätta stödutfodras eller flyttas till bra betesmark för att kunna återhämta sig på populationsnivå. Arbetet pryds även av bilder tagna av den professionella naturfotografen Scott Hurd som tillåtit mig att använda hans bilder.The purpose of this thesis is to investigate the origin of the feral wild horses of Namibia and the factors that have contributed to their survival in the Namib desert for more than a century. Even the horses need of human help, their living situation and further management of the population have been studied. Even though the theories of the horses origin are many, genetic studies have concluded that they origin from domesticated horses of arab-based breeds, eventually from the stud once owned by Emil Kreplin. Through the history of time, the horses have developed in an isolated area under difficult circumstances due to the environment, as periods of thirst, starving and predation. This, with the combination of their genetic background, is what I think have contributed to their desert adaption in a behavioral and physiological way. Because of their unique background the horses have for many years been a popular population for studies on a high level of science, but also a very popular tourist attraction that delivers economical profits to the tourist industry. Today the horses are to be seen in Naukluft Park in Namibia and is visited by thousands of tourists every year. During the last five years the living area of the feral horses has gone through a severe drought, which has caused natural water sources to desiccate and the vegetation to disappear. Since the national park is surrounded by fences and desert, the horses can’t migrate from the area of drought. This, with the combination of an increased amount of hyenas in the park has caused a drastically decreased number of horses, which now makes it impossible to prevent a genetic bottleneck of the population. As the problem has been discussed for a long period of time by different groups in the society, it is now clear that the solution is more or less complicated. The Namibian Wild Horses Foundation wants to relocate the horses to better grazing areas until the rain has fallen and the horses can take care of their own again. Organized groups from the tourist industry wants to relocate either the horses or hyenas, since it is easier by their opinion to manage new packs of hyenas entering the park and would affect the tourism in a lesser degree. The responsible authority, Ministry of Environment and Tourism, has been stuck in limbo with their ambition to make a decision that will be the best for both horses and the tourist industry. As a short term solution they have started to feed both hyenas and horses to reduce the pressure on the horses, which has given a positive effect. But - the decision making about what has to be done to save the horses has taken too long. Today the situation is critical and there’s only about 80 horses left, with no surviving foals in a five years period of time. The solution as I see the problem is that the population of the feral horses of Namibia needs a resilient support on authority level due to the situation we see today. It needs to observes genetically and be provided with a suitable practical planning for further existence. The population will however need to be supplemented with feed or be relocated to better grazing areas to rehabilitate on a population level. The thesis also contains photographs taken by the professional nature photographer Scott Hurd who kindly has given me permission to use his pictures

Antimicrobial Resistance in Vaginal Bacteria in Inseminated Mares

Antimicrobials are added to semen extenders to inhibit the growth of bacteria that are transferred to the semen during collection. However, this non-therapeutic use of antimicrobials could contribute to the development of antimicrobial resistance. The objective of this study was to determine changes in the antibiotic susceptibility of vaginal microbiota after artificial insemination. Swabs were taken from the vagina of 26 mares immediately before artificial insemination and again 3 days later. Bacteria isolated from the vagina at both time points were subjected to antibiotic susceptibility testing and whole-genome sequencing. In total, 32 bacterial species were identified. There were increases in the resistance of Escherichia coli to trimethoprim (p = 0.0006), chloramphenicol and (p = 0.012) tetracycline (p = 0.03) between day 0 and day 3. However, there was no significant effect of exposure to antibiotics in semen extenders with respect to the resistance of Staphylococcus simulans and Streptococcus equisimilis (p > 0.05). Whole-genome sequencing indicated that most phenotypic resistance was associated with genes for resistance. These results indicate that the resistance patterns of vaginal bacteria may be affected by exposure to antibiotics; therefore, it would be prudent to minimize, or preferably, avoid using antibiotics in semen extenders

The influence of antimicrobial agents on the development of antibiotic resistance in the vaginal bacterial flora of artificially inseminated mares

In Sweden and in many other countries, artificial insemination (AI) is frequently used in horse breeding. The technology makes it possible to use genetic material from horses in different geographical locations in an effective way, minimizing the risk of infection or even injury to both horses and stud personnel. Semen collection is performed with a high hygienic standard but despite this, it is seldom possible to obtain an ejaculate that does not contain bacteria. Bacteria in the ejaculate can cause disease in the mare, or result in a deterioration in sperm quality, thereby reducing the chance of the mare becoming pregnant after insemination. To ensure disease control and maintain sperm quality, addition of antibiotics to the semen is therefore required to reduce the number of bacteria in the ejaculate. To protect the spermatozoa during storage, a semen extender containing both buffering and nutrient-rich components, but also antimicrobial substances (AMS) is added. During insemination, the semen dose is deposited in the mare's uterus, which initiates a response from the local immune system. This results in an immunological and mechanical cleansing of the deposited material through the cervix uteri, which is an important function for maintaining a healthy uterine environment and enabling a pregnancy. The mare's vaginal bacterial flora is therefore exposed to the antibiotics contained in the extender, which could theoretically increase the risk of developing antibiotic resistance in the bacterial flora. In this study, vaginal swabs were obtained from 39 mares of varying breeds and ages in northern Sweden, with the aim of investigating the normal vaginal bacterial flora and how its resistance pattern is affected by the exposure to the antibiotics (penicillin and gentamicin) contained in the semen extender INRA-96, and if resistant bacteria are present in the normal vaginal flora of mares. The mares were categorized into either an exposed group consisting of breeding mares at a stud farm, or a control group consisting of mares that had never been inseminated. Swabs were taken from a predetermined area in the cranial vagina just before the first insemination of the season (D0), with a follow-up sample after three days (D3). The control group was sampled only once, as far as possible in connection with estrus. The samples were sent by post to the Department of Biomedical Science and Veterinary Public Health, SLU, Uppsala for analyses. Isolated bacteria were identified by Matrix-Assisted Laser Desorption / Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS). Bacterial species that could be isolated from both D0 and D3 in the same mare were analysed regarding antimicrobial resistance. A comparison was also made between the bacteria and resistance pattern of bacteria from mares that had never been inseminated. A total of 971 bacterial isolates were isolated from the 39 mares, with E. coli being by far the most common isolated bacterium (48.6%). The bacteria included in the antimicrobial susceptibility testing were Staphylococcus simulans, Streptococcus equi ssp. zooepidemicus, Streptococcus dysgalactiae and Enterococcus faecalis. Resistant isolates were identified in all species except Enterococcus faecalis. These isolates showed resistance to penicillin, oxacillin, fusidic acid, trimethoprim, erythromycin, clindamycin, nitrofurantoin and tetracycline, depending on species. Exposure to antibiotics did not affect the resistance pattern in the vaginal bacterial flora in this study, but there was a difference in the bacterial species obtained before and after insemination and between the exposed group and the control group. Resistant bacteria were found in the vaginal flora of both groups.I Sverige och i många andra länder är det vanligt att använda sig av artificiell insemination (AI) inom hästaveln. Tekniken gör det möjligt att på ett smittskyddssäkert och effektivt sätt använda sig av genetiskt material från hästar som befinner sig på olika geografiska platser, med minskad risk för skador på såväl hästar som stuteripersonal. Spermasamling utförs med hög hygienisk standard, men trots de höga kraven på strikt hygien går det sällan att framställa ett ejakulat som inte innehåller bakterier. Bakterier riskerar att orsaka infektioner och försämra spermakvalitén, vilket minskar chansen för stoet att bli dräktigt. För att säkerställa smittskyddet och bibehålla spermakvalitén krävs därför en efterföljande beredning av sperman för att reducera mängden bakterier i ejakulatet. För att skydda spermierna under tiden spermadoser lagras och transporteras tillsätts därför en spädningsvätska innehållande dels buffrande och näringsrika komponenter, men även antimikrobiella substanser (AMS). Vid inseminationen av stoet initieras en respons från det lokala immunförsvaret, vilket resulterar i en immunologisk och mekanisk rensning av det deponerade materialet ut genom cervix uteri. Detta är en viktig funktion för att upprätthålla en hälsosam livmodermiljö och därav möjliggöra en dräktighet. Stoets vaginala bakterieflora exponeras i och med livmoderns mekaniska rensning för de i spädningsvätskan ingående antibiotikumen, vilket teoretiskt kan öka risken för utveckling av antibiotikaresistens hos bakterierna. I denna studie provtogs 39 ston av varierande raser och åldrar i norra Sverige, med syftet att undersöka den normala vaginala bakteriefloran hos ston och hur dess resistensmönster påverkas av exponeringen för de i spädningsvätskan INRA-96 ingående antibiotikumen (penicillin och gentamicin) samt undersöka om resistenta bakterier förekommer i den normala vaginala bakteriefloran. Stona kategoriserades i antingen en exponerad grupp bestående av avelsston på stuteri, samt en kontrollgrupp bestående av ston som aldrig inseminerats. Den exponerade gruppen provtogs från ett förutbestämt område i kraniala vagina just innan den för säsongen första inseminationen (D0) samt med ett uppföljande prov efter tre dagar (D3). Kontrollgruppen provtogs enbart en gång, i högsta möjliga mån i samband med att stoet brunstade. Proverna skickades via post och analyserades på Institutionen för biomedicin och veterinär folkhälsovetenskaps laboratorium vid Sveriges lantbruksuniversitet (SLU) i Uppsala. Påvisade bakterier identifierades via Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS). Bakteriearter som kunde isoleras från både D0 och D3 hos samma sto resistenstestades. Resistensmönstret för dessa bakteriearter jämfördes sedan mellan D0 och D3 samt mot kontrollgruppens resistensresultat av samma bakterieart. Totalt påvisades 971 bakterieisolat från de 39 stona, av vilken E. coli var den överlägset vanligast isolerade bakterien (48.6%). De bakterier som valdes ut för resistensundersökning var Staphylococcus simulans, Streptococcus equi ssp. zooepidemicus, Streptococcus dysgalactiae och Enterococcus faecalis. Resistenta isolat konstaterades hos alla inkluderade bakteriearter utom Enterococcus faecalis mot (beroende på bakterieart) penicillin, oxacillin, fusidinsyra, trimetoprim, erythromycin, clindamycin, nitrofurantoin och tetracyklin. I denna studie påverkade inte exponering av antibiotika i spädningsvätskan resistensmönstret hos den vaginala bakteriefloran. Däremot påverkades vilka bakteriearter som isolerades innan och efter insemination samt mellan den exponerade gruppen och kontrollgruppen. Resistenta bakterier förekom i den vaginala bakteriefloran hos de båda grupperna

Antimicrobial resistance in equine reproduction

Bacteria develop resistance to antibiotics following low-level “background” exposure to antimicrobial agents as well as from exposure at therapeutic levels during treatment for bacterial infections. In this review, we look specifically at antimicrobial resistance (AMR) in the equine reproductive tract and its possible origin, focusing particularly on antibiotics in semen extenders used in preparing semen doses for artificial insemination. Our review of the literature indicated that AMR in the equine uterus and vagina were reported worldwide in the last 20 years, in locations as diverse as Europe, India, and the United States. Bacteria colonizing the mucosa of the reproductive tract are transferred to semen during collection; further contamination of the semen may occur during processing, despite strict attention to hygiene at critical control points. These bacteria compete with spermatozoa for nutrients in the semen extender, producing metabolic byproducts and toxins that have a detrimental effect on sperm quality. Potential pathogens such as Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa may occasionally cause fertility issues in inseminated mares. Antibiotics are added during semen processing, according to legislation, to impede the growth of these microorganisms but may have a detrimental effect on sperm quality, depending on the antimicrobial agent and concentration used. However, this addition of antibiotics is counter to current recommendations on the prudent use of antibiotics, which recommend that antibiotics should be used only for therapeutic purposes and after establishing bacterial sensitivity. There is some evidence of resistance among bacteria found in semen samples. Potential alternatives to the addition of antibiotics are considered, especially physical removal separation of spermatozoa from bacteria. Suggestions for further research with colloid centrifugation are provided

Vaginal Bacteria in Mares and the Occurrence of Antimicrobial Resistance

Antibiotics are added to semen extenders in insemination doses but their effect on the vaginal microbiota of the inseminated female is unknown. The objectives of this study were to define the equine vaginal microbiota and its antimicrobial resistance, and to determine whether it changes after exposure to antibiotics in semen extenders. Vaginal swabs were taken prior to sham-insemination (day 0), and again on days 3, 7, and 14 after insemination. Isolated bacteria were identified by MALDI-TOF and tested for antimicrobial susceptibility by microdilution. The bacteria isolated from the vagina differed according to reproductive status (brood mare or maiden mare), location (north or middle of Sweden), and the stage of the estrous cycle. Five bacterial species were frequently isolated from mares in both locations: Escherichia coli, Staphylococcus capitis, Streptococcus equisimilis, Streptococcus thoraltensis, and Streptococcus zooepidemicus. Overall, vaginal bacteria isolated from inseminated mares showed higher antibiotic resistance than from non-inseminated mares, suggesting a possible link between exposure to antibiotics in the semen extender and the appearance of antimicrobial resistance. The whole-genome sequencing of E. coli isolates from inseminated mares revealed some genes which are known to confer antimicrobial resistance; however, some instances of resistance in these isolates were not characteristic of induced AMR

A relationship between phages and organic carbon in wastewater treatment plant effluents

With stringent effluent requirements and the implementation of new processes for micropollutant removal, it is increasingly important for wastewater treatment plants (WWTPs) to understand the factors affecting effluent quality. Phages (viruses infecting prokaryotes) are abundant in the biological treatment processes. They can contribute to organic carbon in the treated effluent both because they are organic in nature and occur in the effluent and because they cause lysis of microorganisms. Today very little is known about the effects of phages on effluent quality. The goal of this study was, therefore, to determine the relationship between phages and organic carbon in WWTP effluents. We also examined the diversity, taxonomy, and host-association of DNA phages using metagenomics. Effluent samples were collected from four WWTPs treating municipal wastewater. Significant differences in both organic carbon and virus-like particle concentrations were observed between the plants and there was a linear relationship between the two parameters. The phage communities were diverse with many members being taxonomically unclassified. Putative hosts were dominated by bacteria known to be abundant in activated sludge systems such as Comamonadaceae. The composition of phages differed between the WWTPs, suggesting that local conditions shape the communities. Overall, our findings suggest that the abundance and composition of phages are related to effluent quality. Thus, there is a need for further research clarifying the association between phage dynamics and WWTP function