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Kampmann, S., Hampson, B. A., & Pollitt, C. C. (2013). Population dynamics of feral horses (Equus caballus) following above-average rainfall in a semi-arid environment of Australia. Aust Vet J, 91(11), 482–487.
Abstract: Background Recent record rainfall in much of semi-arid Central Australia is the most likely reason for a feral horse population increase in excess of normal. Uncontrolled numbers of feral horses have habitat degradation and animal welfare implications. Objectives The aims of this study were to investigate the social structure of feral horses and assess their population growth rate following unseasonably high rainfall. Methods The study area was 4000 km2 of unmanaged, semi-arid country in Central Australia (latitude 24.50°S, longitude 132.10°E). Horses were identified by descriptive features from ground searches, movement-activated cameras and ‘hides’ positioned at key water holes. Wherever possible, sex and age categories were documented. Population growth rate was estimated by the number of foals divided by the number of horses older than 1 year in the observed population. Results A total of 1424 horses were identified and categorised, of which 335 were foals born within the current year. Only 123 juveniles were identified. Of the adult horses, 53.4% were male and 46.6% were female and this differed from parity (P = 0.04). Of the mares, 71.9% had a foal at foot and the population growth rate was 29.5%. Conclusions With a sustained population growth rate of 29.5%, this population of feral horses will more than double within 3 years. The high population increase will likely have a detrimental effect on native fauna and flora and the fragile, semi-arid ecosystems of Central Australia. After a period of high rainfall and plentiful resources, ‘normal’ drought conditions will return and many feral horses will starve and die as they compete for limited resources.
Keywords: animal welfare; ecology; horses; reproduction; wildlife
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Hampson, B. A., Morton, J. M., Mills, P. C., Trotter, M. G., Lamb, D. W., & Pollitt, C. C. (2010). Monitoring distances travelled by horses using GPS tracking collars. Aust. Vet. J., 88(5), 176–181.
Abstract: Objective The aims of this work were to (1) develop a low-cost equine movement tracking collar based on readily available components, (2) conduct preliminary studies assessing the effects of both paddock size and internal fence design on the movements of domestic horses, with and without foals at foot, and (3) describe distances moved by mares and their foals. Additional monitoring of free-ranging feral horses was conducted to allow preliminary comparisons with the movement of confined domestic horses. Procedures A lightweight global positioning system (GPS) data logger modified from a personal/vehicle tracker and mounted on a collar was used to monitor the movement of domestic horses in a range of paddock sizes and internal fence designs for 6.5-day periods. Results In the paddocks used (0.8-16 ha), groups of domestic horses exhibited a logarithmic response in mean daily distance travelled as a function of increasing paddock size, tending asymptotically towards approximately 7.5 km/day. The distance moved by newborn foals was similar to their dams, with total distance travelled also dependent on paddock size. Without altering available paddock area, paddock design, with the exception of a spiral design, did not significantly affect mean daily distance travelled. Feral horses (17.9 km/day) travelled substantially greater mean daily distances than domestic horses (7.2 km/day in 16-ha paddock), even when allowing for larger paddock size. Conclusions Horses kept in stables or small yards and paddocks are quite sedentary in comparison with their feral relatives. For a given paddock area, most designs did not significantly affect mean daily distance travelled.
Keywords: behaviour; feral horses; foals; global positioning system (GPS); horses; paddock design
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Hampson, B. A., Zabek, M. A., Pollitt, C. C., & Nock, B. (2011). Health and behaviour consequences of feral horse relocation. Rangel. J., 33(2), 173–180.
Abstract: Despite ongoing projects involving the breeding and release of equids into semi-wild and wild environments, insufficient information is available in the literature that describes strategies used by equids to adapt and survive in a novel environment. The aim of this study was to assess the ability of naïve, feral Equus caballus (horse) mares to cope in a novel feral horse environment and investigate possible reasons why some may not survive this challenge. Four mares taken from a semi-arid desert environment remained in good health but significantly changed their movement behaviour pattern when surrounded by prime grazing habitat in a mesic temperate grassland. Three of the four mares captured from the prime grazing habitat and released in the semi-arid desert habitat died, apparently due to stress and/or starvation, within 8 weeks of release. The fourth mare survived 4 months but lost considerable weight.The group of mares relocated to the semi-arid desert environment had difficulty adapting to relocation and did not take up the movement behaviour strategy of local horses, which required long distance treks from a central water hole to distant feeding areas at least 15 km away. The movement behaviour, range use and health consequences of relocating equids may be of interest to wildlife ecologists, animal behaviourists and horse welfare groups. The observations may be used to guide those intending on relocating managed domestic and native horses to novel habitats.
Keywords: equine, GPS, movement, range.
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Milinovich, G. J., Trott, D. J., Burrell, P. C., van Eps, A. W., Thoefner, M. B., Blackall, L. L., et al. (2006). Changes in equine hindgut bacterial populations during oligofructose-induced laminitis. Environ Microbiol, 8(5), 885–898.
Abstract: In the horse, carbohydrate overload is thought to play an integral role in the onset of laminitis by drastically altering the profile of bacterial populations in the hindgut. The objectives of this study were to develop and validate microbial ecology methods to monitor changes in bacterial populations throughout the course of experimentally induced laminitis and to identify the predominant oligofructose-utilizing organisms. Laminitis was induced in five horses by administration of oligofructose. Faecal specimens were collected at 8 h intervals from 72 h before to 72 h after the administration of oligofructose. Hindgut microbiota able to utilize oligofructose were enumerated throughout the course of the experiment using habitat-simulating medium. Isolates were collected and representatives identified by 16S rRNA gene sequencing. The majority of these isolates collected belonged to the genus Streptococcus, 91% of which were identified as being most closely related to Streptococcus infantarius ssp. coli. Furthermore, S. infantarius ssp. coli was the predominant oligofructose-utilizing organism isolated before the onset of lameness. Fluorescence in situ hybridization probes developed to specifically target the isolated Streptococcus spp. demonstrated marked population increases between 8 and 16 h post oligofructose administration. This was followed by a rapid population decline which corresponded with a sharp decline in faecal pH and subsequently lameness at 24-32 h post oligofructose administration. This research suggests that streptococci within the Streptococcus bovis/equinus complex may be involved in the series of events which precede the onset of laminitis in the horse.
Keywords: Animal Feed; Animals; Bacteria/classification/*isolation & purification; DNA, Bacterial/analysis; Disease Models, Animal; Feces/microbiology; Foot Diseases/etiology/microbiology/*veterinary; Horse Diseases/*etiology/metabolism/microbiology; Horses; In Situ Hybridization, Fluorescence; Intestines/*microbiology; Oligosaccharides/*administration & dosage/*metabolism; Phylogeny; Polymerase Chain Reaction; RNA, Bacterial/analysis; RNA, Ribosomal, 16S/analysis
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Kampmann, S.: A., Hampson, B.A., & Pollitt, C. C. (2012). Population dynamics of Australian feral horses in a semiarid environment. In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: Introduction: The feral horse population of Australia is the largest in the world and, in average seasons, increases at a rate of approximately 20% per annum. Recent record rainfall in much of semi-arid Central Australia has led to a population increase in excess of normal rates and this project aimed to document the increase. Uncontrolled feral horse numbers have habitat degradation and horse welfare implications and were the reasons for performing the study. Materials and Methods: The study area was an unmanaged 4,000km2 semi-arid area in Central Australia (Lat 24.50, Long 132.10). The population of feral horses within the study area is estimated to be in excess of 10,000. During an 8 week period at the end of the winter season of 2011, horses were identified by ground searches, movement sensored cameras and from hides positioned at key water holes. The area surveyed represented only a small percentage of the overall habitat. Horses were identified by descriptive features and markings. Where possible, sex and age category were documented. Population growth rate was estimated from the observed sample and was expressed as the number of foals born in the current year, divided by the number of horses older than one year. Results: A total of 1,486 horses were identified and categorised, of which 335 were foals born within the current foaling season. Only 129 juveniles, presumably born in the preceding year, were identified. Of the adult horses, 54% were male and 46% were female. Seventy-four percent of mares (n=452) had a foal at foot and the population growth rate was 29%. Conclusion: With a sustained population growth rate of 29%, this population of feral horses will more than double within 3 years. The high rate of increase is concerning because it will negatively impact on the native fauna and flora and fragile semi-arid ecosystems of Central Australia. In addition the feral horses of the study area have experienced an unusual period of high rainfall and plentiful grazing but a return to normal drought conditions is imminent. Starvation, thirst and death from diminished resources will then be a serious welfare concern for horses. KW -
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Hampson, B. A., de Laat, M. A., Mills, P. C., & Pollitt, C. C. (2012). Distances travelled by feral horses in ‘outback’ Australia. In K. Krueger, & (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: Summary Reasons for performing study: The distance travelled by Australian feral horses in an unrestricted environment has not previously been determined. It is important to investigate horse movement in wilderness environments to establish baseline data against which the movement of domestically managed horses and wild equidae can be compared. Objectives: The aim of this study was to determine the travel dynamics of two groups of feral horses in unrestricted but different wilderness environments. Methods: Twelve feral horses living in two wilderness environments (2,000 km2 vs. 20,000 km2) in outback Australia were tracked for 6.5 consecutive days using custom designed, collar mounted global positioning systems (GPS). Collars were attached after darting and immobilising the horses. The collars were recovered after a minimum of 6.5 days by re-darting the horses. Average daily distance travelled was calculated. Range use and watering patterns of horses were analysed by viewing GPS tracks overlaid on satellite photographs of the study area. Results: Average distance travelled was 15.9 ± 1.9 km/day (range 8.1-28.3 km/day). Horses were recorded up to 55 km from their watering points and some horses walked for 12 hours to water from feeding grounds. Mean watering frequency was 2.67 days (range 1 – 4 days). Central Australian horses watered less frequently and showed a different range use compared to horses from central Queensland. Central Australian horses walked for long distances in direct lines to patchy food sources whereas central Queensland horses were able to graze close to water sources and moved in a more or less circular pattern around the central water source. Conclusions: The distances travelled by feral horses were far greater than those previously observed for managed domestic horses and other species of equidae. Feral horses are able to travel long distances and withstand long periods without water allowing them to survive in semi-arid conditions.
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