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Abstract Background The distribution of resources can affect animal range sizes, which in turn may alter infectious disease dynamics in heterogenous environments. The risk of pathogen exposure or the spatial extent of outbreaks may vary with host range size. This study examined the range sizes of herbivorous anthrax host species in two ecosystems and relationships between spatial movement behavior and patterns of disease outbreaks for a multi-host environmentally transmitted pathogen. Methods We examined range sizes for seven host species and the spatial extent of anthrax outbreaks in Etosha National Park, Namibia and Kruger National Park, South Africa, where the main host species and outbreak sizes differ. We evaluated host range sizes using the local convex hull method at different temporal scales, within-individual temporal range overlap, and relationships between ranging behavior and species contributions to anthrax cases in each park. We estimated the spatial extent of annual anthrax mortalities and evaluated whether the extent was correlated with case numbers of a given host species. Results Range size differences among species were not linearly related to anthrax case numbers. In Kruger the main host species had small range sizes and high range overlap, which may heighten exposure when outbreaks occur within their ranges. However, different patterns were observed in Etosha, where the main host species had large range sizes and relatively little overlap. The spatial extent of anthrax mortalities was similar between parks but less variable in Etosha than Kruger. In Kruger outbreaks varied from small local clusters to large areas and the spatial extent correlated with case numbers and species affected. Secondary host species contributed relatively few cases to outbreaks; however, for these species with large range sizes, case numbers positively correlated with outbreak extent. Conclusions Our results provide new information on the spatiotemporal structuring of ranging movements of anthrax host species in two ecosystems. The results linking anthrax dynamics to host space use are correlative, yet suggest that, though partial and proximate, host range size and overlap may be contributing factors in outbreak characteristics for environmentally transmitted pathogens.

Background: The distribution of resources can affect animal range sizes, which in turn may alter infectious disease dynamics in heterogenous environments. The risk of pathogen exposure or the spatial extent of outbreaks may vary with host range size. This study examined the range sizes of herbivorous anthrax host species in two ecosystems and relationships between spatial movement behavior and patterns of disease outbreaks for a multi-host environmentally transmitted pathogen. Methods: We examined range sizes for seven host species and the spatial extent of anthrax outbreaks in Etosha National Park, Namibia and Kruger National Park, South Africa, where the main host species and outbreak sizes differ. We evaluated host range sizes using the local convex hull method at different temporal scales, within-individual temporal range overlap, and relationships between ranging behavior and species contributions to anthrax cases in each park. We estimated the spatial extent of annual anthrax mortalities and evaluated whether the extent was correlated with case numbers of a given host species. Results: Range size differences among species were not linearly related to anthrax case numbers. In Kruger the main host species had small range sizes and high range overlap, which may heighten exposure when outbreaks occur within their ranges. However, different patterns were observed in Etosha, where the main host species had large range sizes and relatively little overlap. The spatial extent of anthrax mortalities was similar between parks but less variable in Etosha than Kruger. In Kruger outbreaks varied from small local clusters to large areas and the spatial extent correlated with case numbers and species affected. Secondary host species contributed relatively few cases to outbreaks; however, for these species with large range sizes, case numbers positively correlated with outbreak extent. Conclusions: Our results provide new information on the spatiotemporal structuring of ranging movements of anthrax host species in two ecosystems. The results linking anthrax dynamics to host space use are correlative, yet suggest that, though partial and proximate, host range size and overlap may be contributing factors in outbreak characteristics for environmentally transmitted pathogens. [ABSTRACT FROM AUTHOR]

Meat contamination by microorganisms could occur during numerous processes linked to game meat animal slaughter. These contaminants could pose a risk to product quality and consumer health. Contamination often occurs around the wound caused by shooting. Animal slaughter plants are given a responsibility to identify, evaluate and control the occurrence of hazards in their processing plant. To improve this control plan, the effectiveness of lactic (LA) and acetic acids (AA) for reducing the microbiological load directly around the wound was investigated. After killing by means of an aerial (helicopter) shotgun (n = 12) firing lead pellets and land-based rifle bullet shots (n = 36), samples of the flesh directly around the wounds of impala (Aepyceros melampus) were taken immediately after dressing (AD) before any treatment was conducted. Thereafter, at the step where carcasses are typically washed with potable water, the flesh directly around the wound was subjected to a wash with either ≈5 mL potable water (T1), 5% LA solution (T2) or 5% AA solution (T3) and then chilled overnight. Samples of the flesh directly around the wounds were also taken after chilling (AC). The aim of the study was to determine the effectiveness of each organic acid in reducing the microbiological load (total plate count; E. coli; coliforms and Salmonella) present in the flesh directly around the wounds of impala carcasses. The study found that shotgun pellets caused less body damage with fewer microorganisms recorded compared to samples from rifle-killed carcasses. LA reduced the occurrence of Salmonella during slaughter. The results of the other microorganisms revealed inconclusive outcomes on whether the application of water, 5% LA or 5% AA was effective in the reduction of the microbial organisms on the flesh directly around the wounds.

Black-faced impala (Aepyceros melampus ssp. petersi) are endemic to Namibia where conservation management involves immobilisation and translocation, and mortality with current protocols is common. Critically evaluated field immobilisation protocols are needed to maximise animal safety. This prospective study was done in two phases: the first compared etorphine- and thiafentanil-based combinations, the second evaluated the influence of oxygen in impala receiving the thiafentanil-based combination. Animals (10 per group) received 50 mg ketamine (K) and 10 mg butorphanol (B), with either 2.0 mg etorphine (E) or 2.0 mg thiafentanil (T). A third group of ten impala were anaesthetised using TKB with supplemental nasal oxygen (O) at a rate of 5 L/minute. Behavioural, metabolic and physiological variables were assessed within five minutes of recumbency and at 10, 15, and 20 minutes post-recumbency. Statistical analyses for non-parametric data were performed to compare the treatment groups as well as time points; p ≤ 0.05 considered significant. Following darting, 7/10 EKB animals were standing when approached, compared to 2/20 in the thiafentanil treatment groups. Time to first effect was significantly higher for EKB (155 ± 105.7 seconds) compared to TKBO (61.5 ± 21.4 seconds). Time to sternal after darting was significantly higher with EKB (411.6 ± 174 seconds) compared to TKB (160.5 ± 85.4 seconds) and TKBO (166 ± 77.3 seconds). This study builds on previous work investigating the effects of potent opioids on impala and is the first evaluating their use in a field setting. The thiafentanil combination had a faster onset and resulted in a smoother induction than the etorphine combination. Additionally, oxygenation improved in animals receiving oxygen supplementation. [ABSTRACT FROM AUTHOR]

Meat contamination by microorganisms could occur during numerous processes linked to game meat animal slaughter. These contaminants could pose a risk to product quality and consumer health. Contamination often occurs around the wound caused by shooting. Animal slaughter plants are given a responsibility to identify, evaluate and control the occurrence of hazards in their processing plant. To improve this control plan, the effectiveness of lactic (LA) and acetic acids (AA) for reducing the microbiological load directly around the wound was investigated. After killing by means of an aerial (helicopter) shotgun (n = 12) firing lead pellets and land-based rifle bullet shots (n = 36), samples of the flesh directly around the wounds of impala (Aepyceros melampus) were taken immediately after dressing (AD) before any treatment was conducted. Thereafter, at the step where carcasses are typically washed with potable water, the flesh directly around the wound was subjected to a wash with either ≈5 mL potable water (T1), 5% LA solution (T2) or 5% AA solution (T3) and then chilled overnight. Samples of the flesh directly around the wounds were also taken after chilling (AC). The aim of the study was to determine the effectiveness of each organic acid in reducing the microbiological load (total plate count; E. coli; coliforms and Salmonella) present in the flesh directly around the wounds of impala carcasses. The study found that shotgun pellets caused less body damage with fewer microorganisms recorded compared to samples from rifle-killed carcasses. LA reduced the occurrence of Salmonella during slaughter. The results of the other microorganisms revealed inconclusive outcomes on whether the application of water, 5% LA or 5% AA was effective in the reduction of the microbial organisms on the flesh directly around the wounds. [ABSTRACT FROM AUTHOR]

Abstract The majority of Africa's parks and conservation areas have a vast road network, facilitating motorized vehicle game viewing. These roads have an influence that is both road type‐ and species‐specific, on the surrounding ecosystem. Due to their higher traffic volumes, we hypothesized that tar roads and their immediate surrounds within the Kruger National Park, South Africa, are avoided to a greater extent by medium‐to‐large mammals than comparable dirt roads in the park. We systematically recorded the presence of medium‐to‐large mammal species from our vehicle, recording data at 401 tar and 369 dirt road stops in the Kruger National Park. In addition to species presence, we also estimated the proximity of animals to the road, as well as herd sizes. Our results indicate an equal likelihood of viewing the commonly recorded medium‐to‐large mammal species from both road types. The likelihood of observing larger herd sizes was also similar between tar and dirt roads for the three most commonly observed species, African elephant (Loxodonta africana), impala (Aepyceros melampus), and plains zebra (Equus quagga), and the likelihood of viewing impala and zebra close to the road also did not differ between tar and dirt roads. However, elephant was observed more often close to tar roads, compared to dirt roads. We interpreted this as the result of potentially increased woody cover associated with more water runoff in close proximity to tar roads compared with dirt roads. Our results not only have ecological significance, supporting the notion that many of the park's species are habituated to human infrastructure, but also management implications, informing park officials about the influence of road traffic and road type on wildlife distributions.

The majority of Africa's parks and conservation areas have a vast road network, facilitating motorized vehicle game viewing. These roads have an influence that is both road type-and species-specific, on the surrounding ecosystem. Due to their higher traffic volumes, we hypothesized that tar roads and their immediate surrounds within the Kruger National Park, South Africa, are avoided to a greater extent by medium-to-large mammals than comparable dirt roads in the park. We systematically recorded the presence of medium-to-large mammal species from our vehicle, recording data at 401 tar and 369 dirt road stops in the Kruger National Park. In addition to species presence, we also estimated the proximity of animals to the road, as well as herd sizes. Our results indicate an equal likelihood of viewing the commonly recorded medium-to-large mammal species from both road types. The likelihood of observing larger herd sizes was also similar between tar and dirt roads for the three most commonly observed species, African elephant (Loxodonta africana), impala (Aepyceros melampus), and plains zebra (Equus quagga), and the likelihood of viewing impala and zebra close to the road also did not differ between tar and dirt roads. However, elephant was observed more often close to tar roads, compared to dirt roads. We interpreted this as the result of potentially increased woody cover associated with more water runoff in close proximity to tar roads compared with dirt roads. Our results not only have ecological significance, supporting the notion that many of the park's species are habituated to human infrastructure, but also management implications, informing park officials about the influence of road traffic and road type on wildlife distributions. [ABSTRACT FROM AUTHOR]

Many protected areas (PAs) have been created globally in response to the dramatic human-induced decline in biodiversity. However, not all PAs successfully preserve their biodiversity and continued monitoring is vital to assess the effectiveness of conservation efforts. Here, we repeated a study done in 2003 to assess whether investments in anti-poaching in two partially PAs (PPAs), Grumeti Game Reserve (GGR) and Ikona Wildlife Management Area (IWMA), have had quantifiable impacts on impala (Aepyceros melampus) populations, compared to the adjacent strictly protected Serengeti National Park. Since 2003, management of the PPAs has changed dramatically under the non-profit organisation Grumeti Fund. We predicted that if conservation management had improved, impala populations in 2018 would have higher local density, less female-skewed sex ratio, larger group sizes, and shorter flight initiation distances (FID). To assess these parameters of the impala populations, we conducted the same road-based surveys in 2003 and 2018. We found that compared to 2003, impala population density doubled in GGR, group sizes were larger in IWMA and nearly doubled in GGR, and that impala had shorter FID in IWMA in 2018. Our results suggest that the changes in conservation management could have led to the observed positive impacts for impala populations. Our study is encouraging for managers and reveals a conservation success story: if proper action is taken to increase the protection of wildlife within PPAs, wildlife populations may respond quickly and positively.

Impalas (Aepyceros melampus) are common African antelope. A retrospective study was conducted of 251 impala cases from game farms, national parks and zoos submitted by veterinarians and pathologists in South Africa (2003–2016). Histopathology slides as well as records of macroscopic lesions and additional diagnostic tests performed were examined. Non-infectious conditions, such as acute pulmonary congestion and oedema, cachexia, traumatic injury and anaesthetic-related mortality were the most common causes of morbidity and mortality. Bacterial sepsis was the most common infectious disease, whilst skeletal muscle and myocardial sarcocystosis and verminous cholangitis and pneumonia were the most common parasitic diseases. Although the retrospective nature of this study limits the significance of the relative prevalence of lesions in the three locations, management decisions and diagnostic plans may be informed by the results. Impala from game farms had significantly more cachexia cases than those from other locations. Impala from zoos had significantly more lymphoid depletion than those from other locations. These findings suggest that nutrition and pasture management, enclosure design, management of intra- and interspecies aggression and improved anaesthetic protocols could improve animal welfare and survival of impala on game farms and in zoos. This report presents a detailed survey of diseases and conditions found in impala that provides baseline data for veterinary pathologists. [ABSTRACT FROM AUTHOR]

Abstract Background In mammals, homeostasis and survival are dependent on effective trans-membrane movement of ions and enzyme function, which are labile to extreme acid-base changes, but operate efficiently within a narrow regulated pH range. Research in patients demonstrating a pH shifts outside the narrow regulated range decreased the cardiac output and systemic vascular resistance and altered the oxygen binding to haemoglobin. These cardiopulmonary observations may be applicable to the risks associated with anaesthesia and performance of wildlife ungulates on game farms. The aim of this study was to compare blood pH changes over time in impala immobilised and anaesthetised with two different drug protocols (P-TMP - immobilisation: thiafentanil-medetomidine; maintenance: propofol-ketamine-medetomidine; P-EME – immobilisation: etorphine-medetomidine; maintenance: etorphine-ketamine-medetomidine). Additionally, we discuss the resultant blood pH using both the Henderson-Hasselbalch and the Stewart approaches. Two data collection time points were defined, Time1 before maintenance of general anaesthesia and Time 2 at end of maintenance of general anaesthesia. We hypothesise that blood pH would not be different between drug protocols and would not change over time. Results Significant differences were detected over time but not between the two drug protocols. Overall, the blood pH decreased over time from 7.37 ± 0.04 to 7.31 ± 0.05 (p = 0.001). Overall, over time arterial partial pressure of carbon dioxide changed from 51.3 ± 7.5 mmHg to 72.6 ± 12.4 mmHg (p

Environmental productivity is important in determining defensive or tolerance traits of plants, with nutrient-rich savannas showing tolerance and nutrient-poor showing defence traits. Animals are affected differently by such traits due to differences in size, and other characters. We studied differences in browsing as a response to plant traits by elephant, giraffe and impala in Mikumi, a nutrient-poor savanna, and Serengeti, a nutrient-rich savanna, both in Tanzania, for a total of 4 mo; 2 mo at each site. Browsing time on a plant, species and height browsed were recorded. Spinesence reduced biting rate by elephant in Serengeti to 3.8 bites min−1, compared with 4.7 without spines, but had no effect on impala or giraffe. Leaf size affected biting rate by giraffe, decreasing with size in Serengeti from 19.8 bites min−1 to 17.4 bites min−1, increasing in Mikumi, from 17.7 to 19.5 bites min−1, but did not differ in elephant and impala. Biting rate by elephant in Serengeti decreased with browsing height from 0.6 m to 4.2 m and by impala in Mikumi decreased from 0.25 m to 1.5 m, while that of giraffe in Mikumi increased with browsing height, peaking at 4.2 m. The effect was comparable for elephant and impala. [ABSTRACT FROM PUBLISHER]

Background: In mammals, homeostasis and survival are dependent on effective trans-membrane movement of ions and enzyme function, which are labile to extreme acid-base changes, but operate efficiently within a narrow regulated pH range. Research in patients demonstrating a pH shifts outside the narrow regulated range decreased the cardiac output and systemic vascular resistance and altered the oxygen binding to haemoglobin. These cardiopulmonary observations may be applicable to the risks associated with anaesthesia and performance of wildlife ungulates on game farms. The aim of this study was to compare blood pH changes over time in impala immobilised and anaesthetised with two different drug protocols (P-TMP - immobilisation: thiafentanil-medetomidine; maintenance: propofol-ketamine-medetomidine; P-EME - immobilisation: etorphine-medetomidine; maintenance: etorphine-ketamine-medetomidine). Additionally, we discuss the resultant blood pH using both the Henderson-Hasselbalch and the Stewart approaches. Two data collection time points were defined, Time1 before maintenance of general anaesthesia and Time 2 at end of maintenance of general anaesthesia. We hypothesise that blood pH would not be different between drug protocols and would not change over time. Results: Significant differences were detected over time but not between the two drug protocols. Overall, the blood pH decreased over time from 7.37 ± 0.04 to 7.31 ± 0.05 ( p = 0.001). Overall, over time arterial partial pressure of carbon dioxide changed from 51.3 ± 7.5 mmHg to 72.6 ± 12.4 mmHg ( p < 0.001); strong ion difference from 44.6 ± 2.4 mEq/L to 46.9 ± 3.1 mEq/L ( p < 0.001); anion gap from 15.0 ± 3.1 mEq/L to 10.9 ± 2.2 mEq/L ( p < 0.001); and total weak acids from 16.1 ± 1.2 mmol/L to 14.0 ± 1.1 mmol/L ( p < 0.001). The bicarbonate changed from 29.6 ± 2.7 mEq/L to 36.0 ± 4.1 mEq/L ( p < 0.001); and lactate changed from 2.9 ± 1.5 mEq/L to 0.3 ± 0.03 mEq/L ( p < 0.001) over time. Conclusions: The profound increase in the partial pressure of carbon dioxide that worsened during the total intravenous anaesthesia in both protocols initiated a substantial metabolic compensatory response to prevent severe acidaemia. This compensation resulted in a clinically acceptable mild acidaemic state, which worsened over time but not between the protocols, in healthy impala. However, these important compensatory mechanisms require normal physiological function and therefore when immobilising ill or anorexic wild ungulates their acid-base status should be carefully assessed. [ABSTRACT FROM AUTHOR]

In order to develop a long-term anesthesia for flighty antelope species in field situations, two different protocols for induction and maintenance with an intravenous infusion were evaluated in wild-caught impala ( Aepyceros melampus). Ten adult female impala were induced with two induction protocols: one consisted of 0.2 mg/kg medetomidine, 4 mg/kg ketamine, and 0.15 mg/kg butorphanol (MKB) and one consisted of 0.375 mg/kg etorphine, 0.2 mg/kg medetomidine, and 0.2 mg/kg midazolam (EMM). In both treatments, anesthesia was maintained with a continuous intravenous infusion (CII) at an initial dose rate of 1.2 μg/kg per hr medetomidine, 2.4 mg/kg per hr ketaminen and 36 μg/kg per hr midazolam. Partial reversal was achieved with naltrexone (2 : 1 mg butorphanol; 20 : 1 mg etorphine) and atipamezole (5 : 1 mg medetomidine). Evaluation of anesthesia included respiratory rate, heart rate, rectal temperature, arterial blood pressure, oxygen saturation, end tidal carbon dioxide tension, and tidal volume at 5-min intervals, palpebral reflex and response to painful stimuli at 15-min intervals, and arterial blood gases at 30-min intervals. Plasma cortisol concentration was determined after induction and before reversal. Duration and quality of induction and recovery were evaluated. EMM caused a faster induction of 9.5 ± 2.9 min compared to 11.0 ± 6.4 min in MKB. Recovery was also quicker in EMM (EMM: 6.3 ± 5.4 min; MKB: 9.8 ± 6.0 min). However, EMM also produced more cardiopulmonary side effects, including hypoxemia and hypercapnia, and calculated oxygenation indices (PaCO2-PETCO2) were worse than in MKB. One animal died after induction with EMM. The CII provided surgical anesthesia in 7 of 10 animals in MKB and in 9 of 9 animals in EMM for 120 min. In conclusion, the MKB induction protocol had advantages for prolonged anesthesia in impala with significantly less cardiopulmonary depression compared to EMM. The comparably decreased anesthetic depth could easily be adjusted by an increase of the CII. [ABSTRACT FROM AUTHOR]

Objective To characterize a propofolemedetomidine- ketamine total intravenous anaesthetic in impala (Aepyceros melampus). Study design Prospective clinical study. Animals Ten adult female impala. Materials and methods Impala were immobilized at 1253 m above sea level with 2.0 mg thiafentanil and 2.2 mg medetomidine via projectile darts. Propofol was given to effect (0.5 mg kg-1 boluses) to allow endotracheal intubation, following which oxygen was supplemented at 2 L minute-1. Anaesthesia was maintained with a constant-rate infusion of medetomidine and ketamine at 5 mg kg-1 hour-1 and 1.5 mg kg-1 hour-1, respectively, and propofol to effect (initially 0.2 mg kg-1 minute-1) for 120 minutes. The propofol infusion was titrated according to reaction to nociceptive stimuli every 15 minutes. Cardiopulmonary parameters were monitored continuously and arterial blood gas samples were analysed intermittently. After 120 minutes' maintenance, the thiafentanil and medetomidine were antagonized using naltrexone (10:1 thiafentanil) and atipamezole (5:1 medetomidine), respectively. Results All impala were successfully immobilized. The median dose [interquartile range (IQR)] of propofol required for intubation was 2.7 (1.9-3.3) mg kg-1. The propofolemedetomidineeketamine combination abolished voluntary movement and ensured anaesthesia for the 120 minute period. Propofol titration showed a generally downward trend. Median (IQR) heart rate [57 (53-61) beats minute-1], respiratory rate [10 (9-12) breaths minute-1] and mean arterial blood pressure [101 (98e106) mmHg] were well maintained. Arterial blood gas analysis indicated hypoxaemia, hypercapnia and acidaemia. Butorphanol (0.12 mg kg-1) was an essential rescue drug to counteract thiafentanil-induced respiratory depression. All impala regurgitated frequently during the maintenance period. Recovery was calm and rapid in all animals. Median (IQR) time to standing from antagonist administration was 4.4 (3.2-5.6) minutes. Conclusions and clinical relevance A propofolemedetomidineeketamine combination could provide adequate anaesthesia for invasive procedures in impala. The propofol infusion should begin at 0.2 mg kg-1 minute-1 and be titrated to clinical effect. Oxygen supplementation and airway protection with a cuffed endotracheal tube are essential. [ABSTRACT FROM AUTHOR]

Impala ( Aepyceros melampus) are a notoriously difficult species to manage in captivity, and anesthesia is associated with a high risk of complications including mortality. The aim of this study was to compare an opioid-based protocol with an α-2 agonist-based protocol. Nine female impala were studied in a random cross-over design. Subjects received either an etorphine-acepromazine (EA) protocol: 15 μg/kg etorphine and 0.15 mg/kg acepromazine, or a medetomidine-ketamine (MK) protocol: 109 μg/kg medetomidine and 4.4 mg/kg ketamine on day 1. Anaesthesia was repeated 3 days later with the alternative protocol. Subjective assessments of the quality of induction, muscle relaxation, and recovery were made by a blinded observer. Objective monitoring included blood pressure, end-tidal CO2, regional tissue oxygenation, and blood gas analysis. EA provided a significantly quicker (mean EA, 7.17 mins; MK, 17.6 mins) and more-reliable (score range EA, 3-5; MK, 1-5) induction. Respiratory rates were lower for EA with higher end-tidal CO2, but no apnoea was observed. As expected, blood pressures with EA were lower, with higher heart rates; however, arterial oxygenation and tissue oxygenation were equal or higher than with the MK protocol. In conclusion, at these doses, EA provided superior induction and equivalent muscle relaxation and recovery with apparent improved oxygen tissue delivery when compared to MK. [ABSTRACT FROM AUTHOR]

There is a growing necessity to perform long-term anesthesia in wildlife, especially antelope. The costs and logistics of transporting wildlife to veterinary practices make surgical intervention a high-stakes operation. Thus there is a need for a field-ready total intravenous anesthesia (TIVA) infusion to maintain anesthesia in antelope. This study explored the feasibility of an etorphine-ketamine-medetomidine TIVA for field anesthesia. Ten wild-caught, adult impala ( Aepyceros melampus) were enrolled in the study. Impala were immobilized with a standardized combination of etorphine (2 mg) and medetomidine (2.2 mg), which equated to a median (interquartile range [IQR]) etorphine and medetomidine dose of 50.1 (46.2-50.3) and 55.1 (50.8-55.4) μg/kg, respectively. Recumbency was attained in a median (IQR) time of 13.9 (12.0-16.5) min. Respiratory gas tensions, spirometry, and arterial blood gas were analyzed over a 120-min infusion. Once instrumented, the TIVA was infused as follows: etorphine at a variable rate initiated at 40 μg/kg per hour (adjusted according to intermittent deep-pain testing); ketamine and medetomidine at a fixed rate of 1.5 mg/kg per hour and 5 μg/kg per hour, respectively. The etorphine had an erratic titration to clinical effect in four impala. Arterial blood pressure and respiratory and heart rates were all within normal physiological ranges. However, arterial blood gas analysis revealed severe hypoxemia, hypercapnia, and acidosis. Oxygenation and ventilation indices were calculated and highlighted possible co-etiologies to the suspected etorphine-induced respiratory depression as the cause of the blood gas derangements. Impala recovered in the boma post atipamezole (13 mg) and naltrexone (42 mg) antagonism of medetomidine and etorphine, respectively. The etorphine-ketamine-medetomidine TIVA protocol for impala may be sufficient for field procedures of up to 120-min duration. However, hypoxemia and hypercapnia are of paramount concern and thus oxygen supplementation should be considered mandatory. Other TIVA combinations may be superior and warrant further investigation. [ABSTRACT FROM AUTHOR]

The captive bred animal populations showing centric fusion polymorphism can serve as a model for analysis of the impact of the rearrangement on meiosis and reproduction. The synapsis of homologous chromosomes and the frequency and distribution of meiotic recombination events were studied in pachytene spermatocytes of captive bred male impalas ( Aepyceros melampus) polymorphic for der(14;20) by immunofluorescent analysis and fluorescence in situ hybridization. The chromosomes 14 and 20 involved in the centric fusion were significantly shorter due to the loss of sat I repeats indicating ancient origin of the rearrangement. The fused chromosome and the normal acrocentric chromosomes 14 and 20 formed trivalent in pachynema which showed either protruding proximal ends of the acrocentric chromosomes or single axis with synaptic adjustment in the pericentromeric region. There was no significant difference in the number of recombination events per cell between the group of translocation heterozygotes and the animals with normal karyotype. A significant reduction in the number of recombination events was observed in the trivalent chromosomes compared to the normal chromosomes 14 and 20. The level of the recombination reduction was related to the trivalent configuration. The centric fusion der(14;20) was not apparently demonstrated by any spermatogenic defects or reproductive impairment in heterozygous impalas. However, the high incidence of the chromosomal polymorphism within the captive bred population shows the importance of cytogenetic examinations in captive breeding and wildlife conservation programs, especially in the case of reintroduction of the endangered species. [ABSTRACT FROM AUTHOR]

Intestinal contents were collected from eight impala at three different localities during the winter hunting season (2005–2009), as well as from another 24 animals from a one-year trial at a game farm called Ditholo (2003–2004). Gas production, protozoa counts and several other physiological parameters were measured from both rumen and caecum or colon contents. Only higher ophryoscolecid and Isotrichidae species of protozoa were counted and identified. Ostracodinium gracile was present in all 32 impala. Eudiplodinium maggii was present in 31 animals and Eudiplodinium impalae and Epidinium (either ecaudatum or caudatum) in 30 animals. Dasytricha ruminantium was present in only 11 of the impala. Concentrations of protozoa were correlated with the season of sample collection and highly correlated with the animals living on the game farm. Gas production (mL/g of wet rumen ingesta) was weakly correlated with protozoa concentration but not with the season of collection.

The physiological condition of animals connects resources in the environment to demographic responses through reproduction, survival and abundance, and it provides critical information for conservation and management of wildlife populations. We used archived data (early-wet season 1987, late-wet and early-dry season 1988) from culls of impala (Aepyceros melampus) to compare how the kidney fat index (KFI, short-term index of body condition) and carcass mass (long-term index) varied seasonally. For females, KFI increased across seasons, a pattern similar for all age classes. For males, KFI was low and relatively invariable for juveniles and yearlings. For adults, KFI varied with reproductive cycle; highest KFI occurred early in the rut for males and around the second trimester for females. Carcass mass increased over time for growing juveniles and yearlings. For adults, female carcass mass varied according to reproductive cycle and was highest when KFI was highest. Male carcass mass was highest toward the end of the rut when KFI was relatively low. Although changes in body condition can be associated with seasonal changes in forage and activity, KFI and carcass mass are most useful when comparing across years with varying conditions, but within age, sex, and season. [ABSTRACT FROM AUTHOR]

Research has increasingly established that mesoherbivores influence the regeneration of woody plants. However the relationship between mesoherbivore density and degree of impact, and the spatial component of this impact, has not been well established. Using a novel sampling design, we assessed in iMfolozi Park, South Africa, the impact of impala (Aepyceros melampus) across the full complement of woody species within the home range, evaluating its spatial component and relationship to impala density. We used four GPS collars, in separate breeding herds, and a GIS to detect zones of different density of impala in the landscape, thus defining a fine-grain browsing gradient. We assessed impact on woody recruits (≤ 0.5 m height) across this gradient by means of 1600 random 1 × 1-m quadrats. Densities of woody seedlings, and mean percentage of remaining canopy, were significantly less in areas of high impala density versus low-density areas. There was a significant correlation between increasing impala density and decreasing density of favoured woody recruits. We propose a hypothesis of impala-induced patch dynamics. It seems likely that the ubiquitous impala may create and sustain a shifting mosaic of patches, and thus function as a key determinant of landscape heterogeneity. [ABSTRACT FROM PUBLISHER]

Group foraging can be beneficial for ungulates by decreasing the time required for vigilance, but it can also prove costly because of competition. To determine responses to gregarious behaviour, we studied foraging activity and vigilance of impala ( Aepyceros melampus) near Kruger National Park, South Africa. We measured time spent foraging, vigilant, moving, grooming, engaging in social interactions and determined herd size and group distribution (i.e. density). We calculated accepted food abundance (AFA), food ingestion rate, steps per minute and percent vigilance for female, bachelor male and herd male impala. There was no relationship between herd size and vigilance, but vigilance decreased with increasing density ( t1,311 = 4.91, P <0.0001). Additionally, AFA decreased ( t1,61 = 5.96, P <0.0001) and steps per minute increased ( t1,311 = 14.38, P < 0.0001) as more individuals fed in close proximity to each other. Impala could be altering their behaviour to accommodate a perceived change in resources because of intraspecific competition and these adjustments might be related more to the distribution of herd members than to herd size. Further studies should examine the behaviour of gregarious animals in relation to the distribution of herd members in addition to group size. [ABSTRACT FROM AUTHOR]

We investigated the variation in birth synchrony displayed by impala Aepyceros melampus populations across their distribution from southern to eastern Africa. Our analysis was based on field data from Chobe National Park in Botswana and Mala Mala Private Game Reserve in South Africa (4 and 13 years of monitoring, respectively). We compared our results with those from other studies conducted across the impala species range. Impala lambing was highly synchronized in Chobe with 90% of lambs born within 2 weeks in mid-November. Variation in rainfall in the preceding wet season explained 74% of variation in the dates of the first lamb observation in Mala Mala. In Chobe, the earliest birth peak occurred after the highest rainfall and the body condition of lambs in that cohort was also best for both males and females. No association was found between the lunar cycle and the estimated onset of the conception period, despite previous studies having found an association between the lunar cycle and the rutting behaviour in males. On a regional scale, impalas in areas with a marked dry season (several months with no rain) tend to synchronize births with the onset of the rains, when grass quality is highest. Number of months with rain explained 78% of the regional variation in birth synchrony. Neither latitude nor total rainfall contributed significantly to a stepwise multiple regression model. These data support the theory that impalas synchronize births in areas with a highly seasonal food supply, and temporally space births in less seasonal (equatorial) areas to reduce predation risks. [ABSTRACT FROM AUTHOR]

The role of territoriality was investigated by studying 25 impala rams at a reserve in the Waterberg region of South Africa (23°45′S, 28°23′E). Mean territorial tenure was 67.25 days (range 23–99), with a mean territory size of 21.0 ± 11.27 ha, compared with home ranges of 34.1 ± 9.03 ha for territorial rams and 58.8 ± 33.35 ha for bachelor rams, using the fixed kernel method. Territory boundaries remained constant, whilst the area surrounding important features such as water holes, appears to be neutral in terms of territoriality. The rut, as evidenced from peaks in chasing and roaring, lasted for 2 months from 10 April to 10 June 2001, with intensified behaviour including matings observed from 16 May to 4 June 2001. Territorial rams chase and roar more than bachelors. Flehmen and display behaviours are performed by all rams, whilst fights and other reproductive behaviours are generally rare. Bachelors browse more than territorial rams. Only bachelors spar and allogroom, and orally groom themselves more than territorial rams. [ABSTRACT FROM AUTHOR]

The single species of Aepyceros, Aepyceros melampus (impala), is native to central and southern Africa, from Uganda to South Africa. It inhabits open woodlands, sandy bush country and acacia savannah. This study tested the morphological and geographical variation among specimens of impala and their possible relation with described subspecies. Nineteen skull and horn measurements were taken. A multivariate analysis was used and size and shape were explored. Facial coat patterns were also coded. The results supported four out of five traditionally described subspecies: Aepyceros melampus petersi from Angola/Namibia, Aepyceros melampus melampus from South Africa, Aepyceros melampus suara from East Africa and Aepyceros melampus johnstoni from Zambia and Malawi. We consider Aepyceros melampus rendilis to be a synonym of suara. A revised synopsis is suggested, with comments on the geographical ranges of the subspecies. Skull dimensions also allowed us to estimate the geographical origin and subspecies of some individuals of unknown provenance. Coat patterns showed no clear relation with subspecies or geographic location, with the exception of A. m. petersi. [ABSTRACT FROM AUTHOR]

This study investigated the influences of various natural and anthropogenic factors on the vigilance and flight behaviour of impalas in the Save Valley Conservancy, Zimbabwe, using multivariate statistical techniques. The factor that most significantly affected the proportions of time that individuals spent being vigilant and their rates of vigilance was the position of a focal animal in the group; impalas on the periphery of a group were more vigilant than central impalas. Both measures of vigilance were also negatively related to group size. Males spent more total time being vigilant but females raised their heads more often. Impalas spent more time being vigilant in the late afternoon than in the early morning, when greater than ten metres from cover, and when predators had been nearby within the previous six hours. Impalas spent more time vigilant at the property where more impalas were hunted, possibly reflecting the differences in the intensity of hunting by humans on the two properties. Flight distances at the approach of humans were significantly greater at one property than the other, and were also greater for small groups. Further research into the effects of hunting by humans on animals' antipredator behaviours would provide valuable insights for wildlife managers. [ABSTRACT FROM AUTHOR]

In sub-Saharan Africa, the widespread practice of corralling livestock overnight in thorn-scrub "bomas" creates nutrient-enriched patches within rangelands that can subsequently support unique plant communities for decades to centuries after boma abandonment. These nutrient-rich patches (glades) may be preferentially used by native ungulates that coexist with livestock. To evaluate the potential link between cattle management via bomas and habitat for impala (Aepyceros melampus), I examined seasonal patterns of habitat selection by impala and landscape variation in grass nutrient content on a commercial cattle ranch in central Laikipia, Kenya. Studies using automated, infrared camera monitors showed that impala selected nutrient-rich glades 2.6 times more frequently than surrounding Acacia bushland habitat during dry seasons, and 9.6 times more frequently during wet seasons. Significantly greater impala presence in glade versus bushland habitat during dry seasons suggests that impala presence may be related to reduced predation risk in shrub-free glades. The large, significant increase in impala presence in glades from dry to wet seasons suggests that impala distribution also is linked to the availability of nutrient-rich forage. In particular, grass nutrient analyses showed that wet-season phosphorus (P) concentrations in grasses throughout the bushland landscape (x = 2,125 mg P/kg dry matter, varying from 1,789 to 2,922 mg P/kg across topographic positions and from 1,508 to 3,215 mg P/kg among grass species) were below recommended levels for pregnant and lactating ruminants, while mean P concentrations in glade grasses (x ± SE = 5,346 ± 2.92 mg P/kg) exceeded recommended levels. Results suggest that management to increase the relocation rate and distribution of current cattle bomas can have a positive, long-term effect on the local distribution and abundance of impala. [ABSTRACT FROM AUTHOR]