Control and Ecology of the Black-Backed Jackal Canis Mesomelas in the Transvaal

Benthic oxygen demand was measured by dark and light bottle technique at two beaches in the Swartkops estuary, near Port Elizabeth. Respiration of nematodes was measured by polarographic micro-rcspirometer technique. Secondary production was 82 g C/m²/y in sandy areas and 863 g C/m²/y in muddy areas rich in the prawn Callianassa kraussi. Meiofauna production was 1,72 g C/m²/y in sand and 0,24 g C/m²/y in mud. The meiofauna] contribution to secondary production was 2,1% and 0,03% for these two areas respectively. The largest proportion of secondary production was due to micro-organisms: 92% in sand and 73,5% in mud. Macrofauna accounted for 5,75% and 24,4%. It is concluded that meiofauna in these exposed sand and mud flat areas is not quantitatively important, but the qualitative importance may be considerable.     

An Ecophysiological Study of the Meiofauna of the Swartkops Estuary

Environmental correlations with mean, as well as seasonal, distribution and abundance of the meiofauna in two exposed beaches in the Swartkops Estuary, near Port Elizabeth, were elucidated. Population densities showed a direct relationship with particle size. Consequent on this, oxygen appeared to be the controlling factor although desiccation played a role in the intertidal distribution of meiofauna in sandy areas. Seasonal fluctuations in numbers were characterized by peaks occurring in spring and autumn. Variations of temperature and oxygen were found to be responsible for this pattern. The presence of the sand prawn Callianassa kraussi affected both vertical penetration and seasonal fluctuation of the meiofauna. Since fluctuation in nitrogen and chlorophyll a content of the substrate bore little relationship to the fluctuation of the meiofauna, it is concluded that food is not limiting in these areas. Biomass determinations revealed that nematodes, which were the dominant taxon, weighed 0,42 μg individual mean ash-free dry mass and harpacticoid copepods 0,47 μg. On this basis the standing crop biomass was 0,40 μm² in the sandy areas and 0,07 g/m² in the muddier areas, both to a depth of 20 cm.     

Conventional versus high-flow oxygen therapy in dogs with lower airway injury

Dogs with lower airway pathology that present in respiratory distress often receive oxygen therapy as the first line of treatment regardless of the underlying cause. Conventional “low-flow” systems deliver oxygen with a maximum flow rate of 15 L/minute. Traditionally, when an animal’s respiratory status does not improve with conventional oxygen therapy and treatments for underlying disease, options might be limited to either intubation and mechanical ventilation or humane euthanasia. High-flow oxygen therapy (HFOT) has been gaining popularity in veterinary medicine as an alternative route of oxygen supplementation for animals that require support beyond conventional therapy. High-flow oxygen therapy can supply a mixture of air and oxygen via a heated and humidified circuit. It is user friendly and can be used in an environment in which mechanical ventilation is unavailable.This review article is written for emergency doctors and general practitioners who lack access to mechanical ventilation. This article briefly reviews pertinent respiratory physiology, traditional oxygen supplementation techniques, the physiology of HFOT, and the limited evidence available in veterinary medicine regarding the use of HFOT, its applications, and limitations. Guidelines for the use of HFOT are suggested and HFOT is compared to conventional therapy.     

A focus on the European hamster to illustrate how to monitor endangered species

Agriculture intensification, marked by the generalization of crop monoculture, by the increase in plot size and by the reduction of plant diversity, has led to huge decline in wildlife in European farmlands. In such habitat, research has long been biased towards birds and invertebrates, while very few studies have investigated the effect on small mammals. Considering the European hamster, Cricetus cricetus, we therefore review the different techniques that can be used to investigate the impact of environmental changes and conservation measures in small and endangered wild mammals. We suggest that only a multidisciplinary approach will allow exploration of these effects, combining experimental laboratory work on captive‐bred animals with the monitoring of wild individuals. In particular, individual energy balance has to be investigated and measured as accurately as possible, through either biochemical or bio‐logging techniques. It is, indeed, the most affected physiological trait in a changing environment, as it determines both the reproductive output and the survival of the individual. We also discuss the inconvenience of capture–release approaches for such an endangered species and emphasize the disturbance that experimental protocols could impose on the hamster.     

The effect of storage on the P50 of feline blood

Objective: To determine the effect of storage on the P₅₀ of feline hemoglobin. Design: Prospective, in vitro, laboratory study. Subjects: Venous blood from 4 clinically healthy cats. Measurements: Blood was collected into CPDA‐1 anticoagulant/preservative and maintained at 4°C for 5 weeks. Measurements were made on Days 0, 2, 4, 7, 14, 21, 28, and 35. The blood samples were equilibrated in a tonometer to gas mixtures containing 2.5%, 4%, 5%, or 8% oxygen, with 5% carbon dioxide balance nitrogen; pH was adjusted to 7.4. Chloride, partial pressure of oxygen, and hemoglobin saturation were measured; P₅₀ was calculated. Results: Chloride decreased from 124.3±2.1 to 88.5±1.9 mEq/L immediately after dilution with CPDA‐1, and did not change for the 5 weeks thereafter. The P₅₀ decreased from an average of 35.0±1.2 to between 31 and 32 mmHg after 7 days, and did not change further for 4 weeks thereafter. Conclusions: The decrease in P₅₀ of feline hemoglobin was minor compared with that of blood from species in which 2,3‐diphosphoglycerate (2,3‐DPG) is a major modifier of hemoglobin affinity for oxygen. The decrease in P₅₀ in the present study was attributed to an initial decrease in chloride and a subsequent loss of modest quantities of red cell 2,3‐DPG.     

Eutrophication,Ammonia Intoxication,and Infectious Diseases: Interdisciplinary Factors of Mass Mortalities in Cultured Nile Tilapia

The present study was designed to assess the possible causes of the mass mortalities of Nile Tilapia Oreochromis niloticus at El-Behera Governorate, Egypt, in relationship to environmental and microbiotic factors. Water samples were collected from fish farms at different locations and from Lake Edku to analyze water temperature, water pH, salinity, biological oxygen demand, dissolved oxygen, total ammonia nitrogen, and un-ionized ammonia. A number of moribund and freshly dead fish were sampled and submitted to our laboratory for microbiological, molecular, and histopathological examination. Water analysis of the fish farms revealed noticeable increases in the previously mentioned physicochemical parameters. Clinical examinations of moribund fish showed severe gill rot and massive external and internal hemorrhages. Ordinary and molecular laboratory findings confirmed the presence of Branchiomyces sp. in gill tissue and mixed bacterial fish pathogens (Streptococcus agalactiae, Vibrio alginolyticus, V. parahaemolyticus, Pseudomonas anguilliseptica, and P. aeruginosa) in visceral organs. The histopathological and transmission electron microscopic examinations revealed severe necrosis of gill filaments and blockage of branchial blood vessels and lamellar capillaries with Branchiomyces sp. hyphae and spores mixed with different shapes of bacteria. Severe inflammations were detected in liver, kidney, heart, and brain tissues. Ultimately, we can conclude that the syndrome of mass fish kills in this area is a consequence of ecological damage to the aquatic environment, which is mainly related to natural and anthropogenic factors, as well as to the presence of infectious agents.

Received September 30, 2015; accepted April 12, 2016 Published online August 2, 2016     

Effects of Formalin and Chloramine-T Treatments on Oxygen Consumption of Juvenile Salmonids

Abstract

The effects of formalin and chloramine-T on oxygen consumption of juvenile brook trout Salvelinus fontinalis at low water temperature were studied with a flow-through respirometer. No changes were found in the oxygen consumption of these fish after exposure to formalin at 200 and 400 μL/L or to chloramine-T at 10 μL/L during 1-h flow-through treatments. Additionally, there was no evidence of chemical oxygen demand exerted by formalin at dose levels up to 1,600 μL/L or by chloramine-T at I0 μL/L. When juvenile rainbow trout Oncorhynchus mykiss were treated with formalin at 200 μL/L for 1 h in an aerated tank simulating a static bath treatment, sham-treated control tanks had a significantly greater maximum decline in dissolved oxygen than formal in-treated tanks. These studies suggest that posttreatment mortalities that occur after low-temperature bath treatments with these chemicals are not directly related to oxygen consumption.     

Determination of P50 for feline hemoglobin

Objective: The objective of this study was to determine the PO₂ at 50% hemoglobin oxygenation (P₅₀) of feline hemoglobin (Hb). Design: Prospective in vitro laboratory study. Setting: Research laboratory. Animals: Blood from 10 healthy cats. Interventions: Individual blood samples were equilibrated with calibrated gases of 95, 21, 8, 5, 4, and 2.5% oxygen for tonometric analysis. Measurements: Partial pressure of oxygen (PO₂), oxygen content, oxyhemoglobin saturation, methemoglobin (MetHb), carboxyhemoglobin (COHb), Hb, packed cell volume, hydrogen ion concentration (pH), and partial pressure of carbon dioxide (PCO₂) were measured in duplicate for each blood sample by tonometry. The P₅₀ was calculated from both PO₂/oxyhemoglobin saturation and PO₂/oxygen content (per gram of Hb) curves. Main results: The P₅₀ from the PO₂/oxyhemoglobin saturation curve was 35.6 mmHg and from the PO₂/oxygen content (per gram of Hb) curve was 36.2 mmHg. Conclusions: The oxyhemoglobin dissociation curve for the cat is shifted to the right, and thus, feline Hb has lower oxygen affinity compared with human and canine Hb.     

Growth and desiccation of Themeda triandra and Sporobolus fimbriatus in relation to diminishing moisture availability

Abstract

Water was withheld from individual plants of Themeda triandra and Sporobolus fimbriatus growing in pots in a greenhouse. Leaf extension growth, followed by successive degrees of tiller desiccation, were monitored on a daily basis and related to diminishing moisture availability. Leaf extension growth ceased after about 40 % soil water depletion in both species on the sandy clay loam used in the trial. Thereafter, leaves and growing points senesced progressively with increasing evaporative demand, despite a relatively small drop in soil moisture content. The tentative conclusion is that active leaf growth in semi‐arid grassveld takes place in short sporadic spells subsequent to each effective rainfall event. It seems, for example, that after a rain of 50 mm in midsummer, the duration of active leaf growth could be no more than a week.     

Behavioral type,in interaction with body size,affects the recapture rate of brown trout Salmo trutta juveniles in their nursery stream

Movement activity levels of wild animals often differ consistently among individuals, reflecting different behavioral types. Previous studies have shown that laboratory‐scored activity can predict several ecologically relevant characteristics. In an experiment on wild brown trout Salmo trutta, spanning from June to October, we investigated how spring swimming activity, measured in a standardized laboratory test, related to relative recapture probability in autumn. Based on laboratory activity scores, individuals clustered into 2 groups, which showed contrasting patterns in the size‐dependency of their recapture probability. Size had a slightly positive effect on recapture probability for passive fish but a clear negative effect on active fish. Our results show that the population structure in a cohort, in terms of relative proportions of behavioral types in different size classes, can vary over time. The results of this study could depend on either selective mortality or migration. However, selective disappearance of individuals with specific phenotypes, regardless of the mechanism, will have implications for trout population management, such as stocking efficiency of hatchery fish with high growth rates or maintenance of fishways past migration barriers.     

Influence of type of enclosure on exercise fitness of dogs

The effect of various confinement conditions on physical fitness in dogs was evaluated. Eighteen 9.5- to 10-month-old female purpose-bred Beagles were maintained individually for 3 months at a time in 1 of 6 confinement conditions: Condition A--an outdoor housing area with a conventional dog house and free access to a 6.1 x 9.1-m pen; condition B--outdoor kennel with a conventional dog house and free access to a 1.8 x 6.1-m run; condition C--indoor environmentally controlled 1.2 x 3.66-m run; condition D-0.9 x 1.2 x 0.84-m conventional laboratory cage in an indoor environmentally controlled room; condition E--0.9 x 1.2 x 0.84-m conventional laboratory cage in an indoor environmentally controlled room with treadmill exercise (7 km/h at a 10% grade) for 30 min/d, 5 d/wk; condition F--0.71 x 0.86 x 0.69-m conventional laboratory cage in an indoor environmentally controlled room. During the final week of each 3-month interval, muscle succinate dehydrogenase enzyme activities and submaximal exercise heart rates (during treadmill exercise) were determined to estimate physical fitness. Also, 5 days after being moved into a different housing condition, blood samples were collected for plasma cortisol determination. The type of confinement condition for dogs had little effect on muscle succinate dehydrogenase activity, but had a modest effect on submaximal exercise heart rates of dogs.(ABSTRACT TRUNCATED AT 250 WORDS)     

鼠类对玛多县草地表层土壤的影响及沙漠化作用

本文通过野外调查、室内试验分析方法研究了鼠类对玛多县草地表层土壤的破坏及沙漠化作用。结果表明,鼠兔挖掘洞穴,破坏草皮层,将下伏沙砾、土壤推于地表。在鼠害严重的地方,覆盖面积占草地面积的7.47%~16.41%,达到了轻度沙漠化水平。鼠洞洞口塌陷形成风蚀浅坑,风蚀浅坑不断发展,相互贯通,最终发展成"秃斑"和"黑土滩",是草地沙漠化形成的因素之一。     

The effect of various Mycoplasma bovis isolates on bovine leukocyte responses

Mycoplasma bovis (M. bovis) contributes to a number of clinical syndromes in cattle; in particular, chronic pneumonia that is poorly responsive to therapy has been increasingly recognized as an important cause of morbidity, mortality, and financial loss. M. bovis impairs host immune function, but little is known about whether field isolates vary significantly in their effect on immune function. This research tested the hypothesis that different field isolates vary in their ability to suppress cellular metabolism and cellular production of radical oxygen species (ROS) by bovine leukocytes. Total blood leukocytes from 6 cattle were exposed to six field isolates, two diagnostic lab isolates, and two high passage laboratory isolates of M. bovis, and ROS production was measured by oxidation of dihydrorhodamine 123 (DHR-123). Cellular metabolism was measured by reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Significant differences in the response to some field isolates were identified. Three field isolates and both diagnostic lab isolates significantly decreased ROS production by leukocytes from multiple cattle, while the high pass laboratory isolates did not. In contrast, MTT reduction was not significantly impaired by any of the M. bovis strains tested. M. bovis impairs ROS production by bovine leukocytes; the magnitude of the effect appears to be isolate-dependent, and is not related to a general impairment of cellular metabolism. Chronic M. bovis infection in some cattle may be related to impaired ability of leukocytes to produce ROS when exposed to M. bovis.     

Comparison of the composting process using ear corn residue and three other conventional bulking agents during cow manure composting under high‐moisture conditions

To elucidate the characteristics of ear corn residue as a bulking agent, the composting process using this residue was compared with processes using three other conventional materials such as sawdust, wheat straw and rice husk, employing a bench‐scale composting reactor. As evaluated via biochemical oxygen demand (BOD), ear corn residue contains 3.3 and 2.0 times more easily digestible materials than sawdust and rice husk, respectively. In addition, mixing ear corn residue with manure resulted in reduced bulk density, which was the same as that of wheat straw and was 0.58 and 0.67 times lower than that of sawdust and a rice husk mixture, respectively. To evaluate temperature generation during the composting process, the maximum temperature and area under the temperature curve (AUC_TEMP) were compared among the mixed composts of four bulking agents. Maximum temperature (54.3°C) as well as AUC_TEMP (7310°C●h) of ear corn residue were significantly higher than those of sawdust and rice husk (P < 0.05), and they are similar to that of wheat straw mixed compost. Along with the value of AUC_TEMP, the highest organic matter losses of 31.1% were observed in ear corn residue mixed compost, followed by wheat straw, saw dust and rice husk.     

退化沙质草地植物群落物种多样性与土壤肥力的关系

研究了科尔沁退化沙质草地不同沙漠化阶段物种多样性的变化,以及不同植被类型物种多样性与土壤肥力的相互关系。结果表明,沙质草地沙生植被的多样性指数很低,从固定沙丘到流动沙丘,草本层Shannon Wiener多样性指数、Simpson指数和Margalef丰富度指数均降低;0～10 cm表层土壤各因子对多样性的影响不同,有机碳、全氮、全磷、有效氮与Shannon Wiener多样性指数、Simpson指数和Margalef丰富度指数达到显著（P＜0.05）或极显著（P＜0.01）相关关系,而Pielou均匀度指数与这几种土壤肥力指标均无显著相关关系。土壤速效磷和pH值与多样性指数也无显著相关关系。     

Detection of singlet oxygen in blood serum samples of clinically healthy lambs and lambs suffering from alveld disease

Alveld is a disease in lambs of domestic sheep (Ovis aries L.), characterized by a combination of photosensitivity and liver damage. Generation of singlet oxygen play a major role in phototoxicity reactions. The compound phylloerythrin (phytoporphyrin) is so far assumed to be the main photodynamic agent in hepatogenous photosensitivity diseases in sheep. Phylloerythrin is a potent photosensitizer and an efficient source of singlet oxygen. The compound accumulates in the peripheral circualtion upon liver damage. Liver dysfunction is also likely to cause an increase in the blood level of bilirubin. Formation of singlet oxygen by bilirubin is reported. In the present work the photosensitizing potential of serum has been measured and related to the bilirubin- and phylloerythrin levels in lambs suffering from alveld and in clinically healthy controls. The singlet oxygen level of the serum was taken as a measure of the photosensitizing potential. The observed singlet oxygen values in serum from alveld lambs were significantly higher than the corresponding values observed in clinically healthy control lambs. This indicates that the serum of the alveld lambs contains an elevated concentration of photosensitizer. The singlet oxygen level was not correlated to the concentration of bilirubin or phylloerythrin. The results indicate that the photosensitizing mechanism is quite complex and may involve other sensitizer(s) than phylloerythrin.     

Cardiopulmonary effects of thoracoscopy in anesthetized normal dogs

Objective To evaluate the effect of an open‐chest condition on oxygen delivery in anesthetized dogs. Study design Prospective, controlled experimental study. Animals Eight clinically normal adult Walker Hound dogs weighing 25.6–29.2 kg. Methods Eight anesthetized dogs underwent an open‐chest operation after the insertion of thoracoscopy cannulae in the lateral chest walls . A Swan Ganz catheter was used to both measure hemodynamic parameters and obtain mixed venous blood samples for blood gas analysis. A dorsal pedal catheter was placed to both measure arterial blood pressure and obtain blood samples for blood gas analysis. Oxygen delivery index and oxygen extraction ratio were calculated. A randomized block anova for repeated measures was used to evaluate the effect of the treatment on hemodynamic and pulmonary parameters. Results Creation of an open chest did not significantly affect oxygen delivery index (DO₂I; p = 0.545). It induced a significant decrease in arterial oxygen partial pressure (PaO₂; p = 0.018) and arterial oxygen content (CaO₂; p = 0.025). It induced a significant increase in shunt fraction (p = 0.023), physiologic dead space (p = 0.015), and alveolar‐arterial oxygen difference (p = 0.019). Arterial partial pressure of carbon dioxide (PaCO₂; p = 0.766) and arterial hemoglobin oxygen saturation (SaO₂; p = 0.178) were not significantly affected. Diastolic (DPAP; p = 0.050) and mean (MPAP; p = 0.033) pulmonary arterial pressures were significantly increased by opening the chest. Other hemodynamic parameters were not significantly affected. Conclusions Opening the thoracic cavity is not detrimental to hemodynamic function and oxygen delivery in normal dogs, although impaired gas exchange does occur. Clinical relevance Close monitoring of patients is recommended during open‐chest thoracoscopy as adverse effects on gas exchange can contribute to hypoxemia.     

Low Oxygen Tension and Relative Defined Culture Medium with 3, 4‐Dihydroxyflavone are Beneficial for Yak–Bovine Interspecies Somatic Cell Nuclear Transfer Embryo

With an aim to improve the efficiency of yak–bovine interspecies somatic cell nuclear transfer (iSCNT), this study investigated the effect of different culture systems on the development, quality and gene expression profile of yak–bovine iSCNT embryo. Reconstructed embryos were cultured in modified synthetic oviductal fluid (mSOF) or relative defined culture medium (RDCM) with 5% or 20% oxygen tension. Relative mRNA abundance of Oct‐4, IFNT, IGF‐2, Bax, GPX‐1, SOD‐1, CAT and GSS was analysed in blastocysts with qRT‐PCR. The blastocyst formation rate in RDCM under 5% oxygen tension was significantly higher than that under 20% oxygen tension (P < 0.05). The total cell number of blastocyst derived from RDCM with 20% oxygen tension was lower than that of other groups, whereas the group of RDCM with 5% oxygen tension showed a beneficial effect on apoptosis index and tolerance to cryopreservation (P < 0.05). However, under the same oxygen tension, the mRNA abundance of IFNT of RDCM groups was higher than that of the mSOF groups. In addition, high oxygen tension during in vitro culture (IVC) with RDCM significantly increases the mRNA expression of oxidative stress‐related genes (GPX‐1, SOD‐1, CAT and GSS) (P < 0.05). 3, 4‐Dihydroxyflavone (DHF) during high oxygen tension was able to improve the cloned blastocyst formation rate in RDCM (P < 0.05). These results for the first time showed that low oxygen tension and RDCM could improve the developmental competence and quality and alleviate the oxidative stress for yak–bovine iSCNT embryo during IVC.     

Intermittent positive pressure ventilation with constant positive end-expiratory pressure and alveolar recruitment manoeuvre during inhalation anaesthesia in horses undergoing surgery for colic, and its influence on the early recovery period

Objective To compare, ventilation using intermittent positive pressure ventilation (IPPV) with constant positive end‐expiratory pressure (PEEP) and alveolar recruitment manoeuvres (RM) to classical IPPV without PEEP on gas exchange during anaesthesia and early recovery. Study design Prospective randomized study. Animals Twenty‐four warm‐blood horses, weight mean 548 ± SD 49 kg undergoing surgery for colic. Methods Premedication, induction and maintenance (isoflurane in oxygen) were identical in all horses. Group C (n = 12) was ventilated using conventional IPPV, inspiratory pressure (PIP) 35–45 cmH₂O; group RM (n = 12) using similar IPPV with constant PEEP (10 cmH₂O) and intermittent RMs (three consecutive breaths PIP 60, 80 then 60 cmH₂O, held for 10–12 seconds). RMs were applied as required to maintain arterial oxygen tension (PaO₂) at >400 mmHg (53.3 kPa). Physiological parameters were recorded intraoperatively. Arterial blood gases were measured intra‐ and postoperatively. Recovery times and quality of recovery were measured or scored. Results Statistically significant findings were that horses in group RM had an overall higher PaO₂ (432 ± 101 mmHg) than those in group C (187 ± 112 mmHg) at all time points including during the early recovery period. Recovery time to standing position was significantly shorter in group RM (49.6 ± 20.7 minutes) than group C (70.7 ± 24.9). Other measured parameters did not differ significantly. The median (range) of number of RMs required to maintain PaO₂ above 400 mmHg per anaesthetic was 3 (1–8). Conclusion Ventilation using IPPV with constant PEEP and RM improved arterial oxygenation lasting into the early recovery period in conjunction with faster recovery of similar quality. However this ventilation mode was not able to open up the lung completely and to keep it open without repeated recruitment. Clinical relevance This mode of ventilation may provide a clinically practicable method of improving oxygenation in anaesthetized horses.