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The active–inactive model predicts temporal variation in the operational sex ratio (OSR) throughout a breeding season, as a function of each male’s optimal strategy for finding mates. I tested the model using data for the raucous toad, Bufo rangeri, collected nightly over three breeding seasons. The numbers of active males and fertilizable females were correlated in two of the three breeding seasons. The OSR, defined as the average ratio of sexually active males to fertilizable females, decreased throughout each season, except for the first, when it rose to a peak before decreasing. The OSR fluctuated towards the end of the season in two of the three seasons, and rose again at the end in only one. Although the equal-performance assumption was violated, the temporal pattern of the OSR in this species complied largely with that predicted by the active–inactive model. Reasons for deviations from the model’s predictions are discussed. Despite the lack of data on mortality rates, this study represents the most comprehensive test of the model yet, as tests on other species have been based on data collected intermittently, as opposed to nightly, over only two breeding seasons. 相似文献
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Marina REYNE Sarah HELYAR Aurélie AUBRY Mark EMMERSON Ferdia MARNELL Neil REID 《Integrative zoology》2021,16(2):240-254
According to the International Union for Conservation of Nature Red List, 41% of the world's amphibian species are threatened with extinction, making them more threatened than any other vertebrate group nowadays. Given the global amphibian crisis, comprehensive understanding of demographics and population trends of declining and threatened species is essential for effective management and conservation strategies. Counting egg spawns is widely used to assess population abundance in pond breeding anurans. However, it is unknown how such counts translate into robust population size estimations. We monitored the breeding activity of the Natterjack toad (Epidalea calamita), combining egg string counts and individual photo-identification with Capture-Mark-Recapture population size and operational sex ratio estimation. Male Natterjack toads were identified by the pattern of natural markings with repeated ID of the same individual confirmed for 10% of the samples using genetic fingerprinting. We identified 647 unique individuals within a closed study population at Caherdaniel, Co Kerry. Population estimates derived from egg string counts estimated a breeding population of 368 females (95% CI 353–384) and Capture-Mark-Recapture estimated a breeding population of 1698 males (95% CI 1000–2397). The female:male sex ratio was conservatively estimated at 1:5 (95% CI 1:3–1:6) where 62% ± 6% of females were assumed to spawn. These substantially departed from any priori assumption of 1:1 which could have underestimated the breeding population by up to 72%. Where amphibian absolute population size estimation is necessary, methods should include empirical survey data on operational sex ratios and not rely on assumptions or those derived from the literature which may be highly population and/or context-dependent. 相似文献
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诱导蟾蜍排卵及蝌蚪生长发育规律的试验研究 总被引：1，自引：0，他引：1
研究了蟾蜍受精卵的孵化过程 ,对蝌蚪的生长、发育、变态及幼蛙的生长特性等方面进行了观察和测量 ,同时 ,采用人工诱导排卵的方法 ,进行了蟾蜍在人工条件下的受精试验 ,并对人工诱导的蟾蜍卵细胞进行了孵化试验。结果表明 ,自然条件和人工诱导条件均能够完成蝌蚪的孵化和发育 ,但是在蝌蚪的变态阶段存在较高的死亡率。 相似文献
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Cloacal swabs and caecal contents sampled from 58 cane toads (Bufo marinus) in St George’s parish, Grenada, during a 7‐month period in 2011 were examined by an enrichment and selective culture method for presence of Salmonella spp. Twenty‐four (41%) toads were positive for Salmonella spp. of which eight were Salmonella enterica serovar Javiana, and eight were S. enterica serovar Rubislaw. The other serovars were as follows: Montevideo, 6; Arechavaleta, 1; and serovar: IV:43:‐:‐, 1. The high frequency of isolation of serovar Javiana, an emerging human pathogen associated with several outbreaks in the recent years in the eastern United States, suggests a possible role for cane toads in transmission of this serovar. Although S. Rubislaw has been isolated from lizards, bats and cases of some human infections, there is no report of its carriage by cane toads, and in such high frequency. The rate of carriage of S. Montevideo, a cause for human foodborne outbreaks around the world was also over 10% in the 58 toads sampled in this study. The antimicrobial drug susceptibility tests against amoxicillin‐clavulanic acid, ampicillin, cefotaxime, ceftazidime, ciprofloxacin, enrofloxacin, gentamicin, imipenem, nalidixic acid, streptomycin, tetracycline and trimethoprim‐sulfamethoxazole showed that drug resistance is minimal and is of little concern. Antimicrobial resistance was limited to ampicillin and amoxicillin‐clavulanic acid in one isolate of S. Javiana and one isolate of S. Rubislaw. This is the first report of isolation and antimicrobial susceptibilities of various Salmonella serovars not identified previously in cane toads in Grenada, West Indies. 相似文献
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试验旨在探讨硫化氢供体硫氢化钠改善疲劳状态下肌力减退的作用。采用脉冲式电流直接刺激腓肠肌作为疲劳模型,对比硫氢化钠和任氏液分别对蟾蜍腓肠肌疲劳的影响。结果表明,硫氢化钠在浓度为5×10-4、1×10-3、2×10-3 mol/L时,离体腓肠肌达到最大收缩幅度90%、50%和10%的时间极显著长于在任氏液作用下的离体腓肠肌(P<0.01);5.6 mg/kg硫氢化钠也极显著延长了在体腓肠肌达到最大收缩幅度90%、50%和10%的时间(P <0.01)。表明外源性硫化氢具有延缓肌肉疲劳的作用。 相似文献
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利用经分类鉴定并保存于固定培养基中的ＡＨ９８０４嗜水气单胞菌株对黑斑蛙和花背蟾蜍进行动物接种感染试验（腹腔接种剂量２ｍＬ、含菌数１４４×１０８个），结果显示，该菌对上述２种动物具有明显的致病作用。同时，使用所制备高免血清作了同种动物免疫保护试验（血清抗体效价１２８０、肌肉接种剂量３０ｍＬ），对其结果进行了验证。 相似文献
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试验旨在探讨盐地碱蓬甜菜红素改善疲劳状态下肌力减退的作用。采用脉冲式电流直接刺激腓肠肌作为疲劳模型,对比盐地碱蓬甜菜红素和任氏液分别对蟾蜍腓肠肌疲劳的影响。结果表明,盐地碱蓬甜菜红素在浓度为0.005、0.01、0.02 mg/mL时,离体腓肠肌达到最大收缩幅度90%、50%和10%的时间显著长于在任氏液作用下的离体腓肠肌(P<0.05);0.02 mg/mL的盐地碱蓬甜菜红素也极显著的延长了在体腓肠肌达到最大收缩幅度90%、50%和10%的时间(P<0.01)。因此,盐地碱蓬甜菜红素具有延缓肌肉疲劳的作用。 相似文献
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Gordon ME McKeever KH Betros CL Manso Filho HC 《Veterinary journal (London, England : 1997)》2007,173(3):532-540
Six Standardbred (STB) mares (11+/-2 years, 521+/-77 kg; means+/-SD) performed an exercise trial (EX) where they underwent an incremental exercise test (GXT) as well as a parallel control trial (CON) to test the hypothesis that short-term, high intensity exercise would alter plasma concentrations of glucose, leptin, adiponectin, ghrelin, insulin and cortisol. Plasma samples were taken before (0 min), during (last 10s at 6, 8m/s, and the velocity eliciting VO(2max)), and after exercise (2, 10, 30, 60 min; 12 and 24h post-GXT). A second set of blood samples was collected before and after an afternoon meal given at 1515 h (at 1500, 1514, 1530, and 1545 h). Data were analyzed using ANOVA for repeated measures and Tukey's test. During the GXT, there were no changes (P>0.05) in the plasma concentrations of glucose, leptin, adiponectin or ghrelin. However, there was a 29% increase (P<0.05) in mean plasma cortisol concentration and a 35% decrease (P<0.05) in mean plasma insulin concentration. Substantial increases (P<0.05) in the mean plasma concentrations of glucose and cortisol of 36% and 102%, respectively, were seen in the EX trial during the first 60 min post-GXT. Plasma leptin concentration, measured at the 24h post-GXT time point, was 20% lower (P<0.05) during the EX trial compared with the parallel time point in the standing control (CON) trial. Plasma ghrelin concentration was 37% lower (P<0.05) in the EX trial compared with CON before and after the afternoon meal, but was 43% higher (P<0.05) 12h post-GXT. There were no differences between EX and CON for plasma concentrations of insulin or adiponectin during recovery. It was concluded that short-term high intensity exercise alters plasma leptin and ghrelin concentrations in STB mares post-exercise, which may signal the exercised animals to alter energy intake. 相似文献
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Serologic prevalence of toxoplasmosis in cattle, sheep, goats, pigs, bison, and elk in Montana 总被引：2，自引：0，他引：2
J P Dubey 《Journal of the American Veterinary Medical Association》1985,186(9):969-970
Serum samples from 2,539 cattle, 649 sheep, 123 goats, 413 pigs, 93 bison, and 56 elk from Montana were examined for antibody to Toxoplasma gondii in the Sabin-Feldman dye test or the modified agglutination test (MAT). Cattle, bison, and elk serum samples were treated with 0.2 M-mercaptoethanol before examination in MAT. In the dye test, 13.2% of sheep, 5.0% of pigs, and 22.7% of goats had antibody at a dilution of greater than or equal to 1:16. In the MAT, 3.2% of cattle, 3.1% of bison, and none of the elk were positive at a dilution of greater than or equal to 1:128. 相似文献
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Sun M Zhuo W Guo S Liao S Shi D Liu J Cheng Z Liu Y Niu X Wang S Yang D 《Veterinary parasitology》2012,185(2-4):225-228
The present study conducts a serological survey on the presence of canine dirofilariosis in domestic dogs using an enzyme-linked immunosorbent assay (ELISA) kit. A total of 310 household dogs (166 females and 144 males) in Chongqing, Kunming, Nanchang, Fuzhou, Guangzhou, Shenzhen, and Nanning in Southern China were examined. Of the 310 dogs, 42 (13.5%) were seropositive for dirofilariosis. No statistically significant difference was observed in terms of sex in the seroprevalence of dirofilariosis using the ELISA kit. The positive rates for dirofilariosis were 6.6% in the 0-1-year-old group, 13.8% in the 1-4-year-old group, and 21.6% in the less than 4-year-old group. The statistical analysis revealed that significant differences were observed in the 1-4-year-old group (P=0.037, OR=0.441, 95% CI=0.170-1.144) and less than 4-year-old group (P<0.001, OR=0.256, 95% CI=0.095-0.693). In the regional comparison, the shoreline city Shenzhen (18.8%) had a significantly higher prevalence than urban and mountain areas (P<0.05, OR=0.310, 95% CI=0.066-1.445). In conclusion, Dirofilaria immitis infection in domestic dogs was present in Chongqing, Kunming, Nanchang, Fuzhou, Guangzhou, Shenzhen, and Nanning. Therefore, heartworm treatment and/or chemoprophylaxis for the captured domestic dogs are necessary in these areas. To the best of our knowledge, the present study is the first using serological methods to examine D. immitis infection in domestic dogs in Mainland China in the recent years. 相似文献
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Six insulin-sensitive and 6 insulin-insensitive mares were used in a replicated 3 by 3 Latin square design to determine the pituitary hormonal responses (compared with vehicle) to sulpiride and thyrotropin-releasing hormone (TRH), 2 compounds commonly used to diagnose pituitary pars intermedia dysfunction (PPID) in horses. Mares were classified as insulin sensitive or insensitive by their previous glucose responses to direct injection of human recombinant insulin. Treatment days were February 25, 2012, and March 10 and 24, 2012. Treatments were sulpiride (racemic mixture, 0.01 mg/kg BW), TRH (0.002 mg/kg BW), and vehicle (saline, 0.01 mL/kg BW) administered intravenously. Blood samples were collected via jugular catheters at −10, 0, 5, 10, 20, 30, 45, 60, 90, and 120 min relative to treatment injection. Plasma ACTH concentrations were variable and were not affected by treatment or insulin sensitivity category. Plasma melanocyte-stimulating hormone (MSH) concentrations responded (P < 0.01) to both sulpiride and TRH injection and were greater (P < 0.05) in insulin-insensitive mares than in sensitive mares. Plasma prolactin concentrations responded (P < 0.01) to both sulpiride and TRH injection, and the response was greater (P < 0.05) for sulpiride; no effect of insulin sensitivity was observed. Plasma thyroid-stimulating hormone (TSH) concentrations responded (P < 0.01) to TRH injection only and were higher (P < 0.05) in insulin-sensitive mares in almost all time periods. Plasma LH and FSH concentrations varied with time (P < 0.05), particularly in the first week of the experiment, but were not affected by treatment or insulin sensitivity category. Plasma GH concentrations were affected (P < 0.05) only by day of treatment. The greater MSH responses to sulpiride and TRH in insulin-insensitive mares were similar to, but not as exaggerated as, those observed by others for PPID horses. In addition, the reduced TSH concentrations in insulin-insensitive mares are consistent with our previous observation of elevated plasma triiodothyronine concentrations in hyperleptinemic horses (later shown to be insulin insensitive as well). 相似文献
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Leandro Maia Maria Vernica de Souza MV MS DS Raphael Bragana Alves Fernandes BS MS DS Maurício Paulo Ferreira Fontes BS MS PhD Matheus Werner de Souza Vianna Walcrisley Vercelli Luz BS MS 《Journal of Equine Veterinary Science》2006,26(12):578-583
Pollution is a subject of worldwide concern and discussion and various areas of science are seeking to integrate their knowledge in an attempt to improve understanding of the harmful effects of modern human activities. Thus, the objective of the current study was to assess the potential for using the horse as a bio-indicator of environmental pollution. Blood and serum samples from 120 horses from locations with different degrees of urbanization and industrialization and the feeds used for these animals were analyzed to determine their heavy metal (Cd, Pb, Ni, Cu, and Zn) content. The data obtained were compared. The results did not show increases in heavy metal concentration in the blood and serum of the horses with the intensification of urbanization and industrialization around the farms. Only Cd, as determined in the blood of the animals, showed a certain potential for using horses as bio-indicators of environmental pollution. The data for sex, age, and chemical composition of the foodstuffs supplied to the animals were not determinants in explaining the variation in the concentrations of heavy metals observed. 相似文献
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Franz S Kahlbacher H Schuh M Schmerold I 《Berliner und Münchener tier?rztliche Wochenschrift》2004,117(3-4):153-159
The aim of this study was to investigate in 20 healthy pigs the practicability of the oesophagogastroduodenoscopic examination technique in regard to equipment, method of examination, indications and its suitability as a diagnostical tool for the assessment of the oesophagus, stomach and upper duodenum in one procedure. Preparation of the patient for endoscopy, the procedure of the endoscopic examination as well as the topographical findings of the upper intestinal tract including the duodenum until the flexura duodenojejunalis are described. Flexible oesophagogastroduodenoscopy is a suitable method for the observation and natural visualisation of mucosal surfaces and for the digital documentation of peristaltic movements. The procedure is easy to perform in anaesthetized animals, is in most cases completed within 15 min, and can be repeated in the same animal. Indications of this interesting diagnostic imaging technique are discussed. 相似文献