RESUMEN
Rumen content stratification and the degree of dissociation of particle and fluid retention in the reticulorumen differ between 'moose-type' and 'cattle-type' ruminant species. These differences are not strictly linked to diet, except for a seeming limitation of 'moose-type' ruminants to a browsing niche. Nevertheless, these differences can be plausibly linked to other observed differences in ruminants, such as the intraruminal papillation pattern, or the size of the omasum. However, many of the corresponding measures are still only available for a restricted number of species. Here, we investigated the dry matter (i.e., the inverse of the moisture) concentration in forestomach contents of 10 blackbuck (Antilope cervicapra) and 7 Arabian sand gazelle (Gazella subgutturosa marica), and quantified the rumen papillation pattern. The blackbucks had distinct rumen contents stratification, with more moisture in ventral than in dorsal contents (difference 3.6% units, P < 0.001), whereas this difference was much less pronounced in the sand gazelles (0.6% units, P = 0.227). While reticulum contents were particularly moist in both species, omasum contents were particularly dry in sand gazelles, but did not differ in moisture from rumen contents in the blackbuck. This species is an outlier among ruminants due to its extremely small omasum. The intraruminal papillation pattern did not differ between blackbucks and sand gazelles and showed a surface enlargement factor (SEF) in the dorsal rumen of 27-28% of the SEF in the Atrium ruminis. Compared to data on digesta retention in the same species, the findings are in line with the overall concept of a high fluid throughput causing a distinct stratification of rumen contents and intraruminal papillation, and necessitating a large omasum for fluid re-absorption. However, the data also show that individual species may not correspond to all the assumptions of the concept, suggesting taxon-specific differences between species. Reasons for these differences cannot be linked to a dietary grass-browse spectrum, but may lie in evolutionary contingency.
Asunto(s)
Antílopes/fisiología , Ciervos/fisiología , Estómago/metabolismo , Alimentación Animal , Animales , Bovinos , Dieta , Femenino , Tracto Gastrointestinal/fisiología , Masculino , Filogenia , Rumen/metabolismo , Rumen/fisiología , Rumiantes/fisiología , Especificidad de la EspecieRESUMEN
The black rhinoceros (Diceros bicornis) is a critically endangered species facing multiple anthropogenic pressures in its natural home range across Africa. Black rhinoceros are difficult to maintain ex situ and subject to diseases that are linked with captive dietary factors. Hemochromatosis is of particular concern, as it is a common finding at necropsy of captive adults, and has been linked to excessive dietary iron intake. This intake study investigates the select nutrient composition of the diets offered to and consumed by five captive black rhinoceros in a UK zoo to evaluate, ensure adequacy, and/or make adjustments if necessary. Alfalfa hay, pellets and six browse species offered were analyzed for iron (Fe), copper (Cu), vitamin E, and tannic acid content. Intakes were quantified and evaluated against levels found in wild diets and the currently available feeding guidelines for black rhinoceros. Diets eaten by five individual rhinoceros (1.4%-2.3% of bodyweight dry matter [DM] intake), comprising 68%-82% hay, 6%-13% pellets, and 13%-27% browse, contained 76-98 mg/kg Fe (on a DM basis), fell within the ranges of plants eaten by free-ranging rhinoceros (45-140 mg/kg DM), as well as values recommended for captive-fed browsing rhinoceros (50-100 mg/kg DM). Consumed diets were found to be marginal to adequate in Cu (9-11 mg/kg DM) compared with the recommended 10 mg/kg DM; dietary vitamin E ranged from 54 to 79 IU/kg DM, and tannic acid measured 13-14 g/kg DM. Commercial pellets were the primary contributor of dietary Fe, Cu, and vitamin E, containing up to 10 times more of each of those nutrients than the forages. Native browses were important sources of lower Fe ingredients, as well as appropriate levels of dietary Cu and vitamin E (dependent on species). Interestingly, pellets (23 g/kg) and alfalfa hay (14 g/kg) contained higher concentrations of tannic acid compared with any of the browses fed (4-13 g/kg). All nutritional parameters evaluated were close to recommended dietary levels, diets resembled values consumed in the wild, and the animals remained clinically healthy throughout the study. Overall, diets were considered nutritionally adequate for captive feeding of black rhinoceros; evaluating the nutrient composition of all ingredients, including browse plants in diets, provides important information for achieving optimal nutrient balance.
Asunto(s)
Dieta/veterinaria , Ingestión de Alimentos , Perisodáctilos , Alimentación Animal/análisis , Crianza de Animales Domésticos/métodos , Animales , Animales de Zoológico , Cobre/análisis , Femenino , Hierro de la Dieta/análisis , Masculino , Taninos/análisis , Reino Unido , Vitamina E/análisisRESUMEN
This study evaluated the accuracy of pulse oximetry, capnography, and oscillometric blood pressure during general anesthesia in giraffes (Giraffa camelopardalis). Thirty-two giraffes anesthetized for physiologic experiments were instrumented with a pulse oximeter transmittance probe positioned on the tongue and a capnograph sampling line placed at the oral end of the endotracheal tube. A human size 10 blood pressure cuff was placed around the base of the tail, and an indwelling arterial catheter in the auricular artery continuously measured blood pressure. Giraffes were intermittently ventilated using a Hudson demand valve throughout the procedures. Arterial blood for blood gas analysis was collected at multiple time points. Relationships between oxygen saturation as determined by pulse oximetry and arterial oxygen saturation, between arterial carbon dioxide partial pressure and end-tidal carbon dioxide, and between oscillometric pressure and invasive arterial blood pressure were assessed, and the accuracy of pulse oximetry, capnography, and oscillometric blood pressure monitoring evaluated using Bland-Altman analysis. All three noninvasive methods provided relatively poor estimates of the reference values. Receiver operating characteristic curve fitting was used to determine cut-off values for hypoxia, hypocapnia, hypercapnia, and hypotension for dichotomous decision-making. Applying these cut-off values, there was reasonable sensitivity for detection of hypocapnia, hypercapnia, and hypotension, but not for hypoxemia. Noninvasive anesthetic monitoring should be interpreted with caution in giraffes and, ideally, invasive monitoring should be employed.
Asunto(s)
Análisis de los Gases de la Sangre/veterinaria , Determinación de la Presión Sanguínea/veterinaria , Jirafas/fisiología , Monitoreo Fisiológico/veterinaria , Oximetría/veterinaria , Anestesia General/veterinaria , AnimalesRESUMEN
Ruminants differ in the degree of rumen content stratification, with 'cattle-types' (i.e., the grazing and intermediate feeding ruminants) having stratified content, whereas 'moose-types' (i.e., the browsing ruminants) have unstratified content. The feeding ecology, as well as the digestive morphophysiology of the giraffe (Giraffa camelopardalis), suggest that it is a 'moose-type' ruminant. Correspondingly, the giraffe should have an unstratified rumen content and an even rumen papillation pattern. Digesta samples were collected from along the digestive tract of 27 wild-caught giraffes kept in bomas for up to 2months, and 10 giraffes kept in zoological gardens throughout their lives. Samples were analysed for concentration of dry matter, fibre fractions, volatile fatty acids and NH3, as well as mean particle size and pH. There was no difference between the dorsal and ventral rumen region in any of these parameters, indicating homogenous rumen content in the giraffes. In addition to the digesta samples, samples of dorsal rumen, ventral rumen and atrium ruminis mucosa were collected and the papillary surface enlargement factor was determined, as a proxy for content stratification. The even rumen papillation pattern observed also supported the concept of an unstratified rumen content in giraffes. Zoo giraffes had a slightly more uneven papillation pattern than boma giraffes. This finding could not be matched by differences in physical characteristics of the rumen content, probably due to an influence of fasting time ante mortem on these parameters.
Asunto(s)
Jirafas/metabolismo , Rumen/metabolismo , AnimalesRESUMEN
Giraffes--the tallest extant animals on Earth--are renowned for their high central arterial blood pressure, which is necessary to secure brain perfusion. Arterial pressure may exceed 300â mmHg and has historically been attributed to an exceptionally large heart. Recently, this has been refuted by several studies demonstrating that the mass of giraffe heart is similar to that of other mammals when expressed relative to body mass. It thus remains unexplained how the normal-sized giraffe heart generates such massive arterial pressures. We hypothesized that giraffe hearts have a small intraventricular cavity and a relatively thick ventricular wall, allowing for generation of high arterial pressures at normal left ventricular wall tension. In nine anaesthetized giraffes (495±38â kg), we determined in vivo ventricular dimensions using echocardiography along with intraventricular and aortic pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4â lâ min(-1), respectively. End-diastolic and end-systolic volumes were 521±61â ml and 228±42â ml, respectively, yielding an ejection fraction of 56±4% and a stroke volume of 0.59â mlâ kg(-1). Left ventricular circumferential wall stress was 7.83±1.76â kPa. We conclude that, relative to body mass, a small left ventricular cavity and a low stroke volume characterizes the giraffe heart. The adaptations result in typical mammalian left ventricular wall tensions, but produce a lowered cardiac output.
Asunto(s)
Gasto Cardíaco , Jirafas/fisiología , Volumen Sistólico , Función Ventricular , Animales , Presión Sanguínea , Ecocardiografía/veterinaria , MasculinoRESUMEN
The digestive tract anatomy of 14 blackbucks (Antilope cervicapra) and seven Arabian sand gazelles (Gazella subgutturosa marica) was quantified by dimensions, area and weight. Data from the two small-sized antilopinae were evaluated against a larger comparative data set from other ruminants classified as having either a 'cattle-type' or 'moose-type' digestive system. The digestive anatomy of the blackbuck resembled that of 'cattle-type' ruminants, which corresponds to their feeding ecology and previous studies of solute and particle retention time; however, a surprising exception was the remarkably small omasum in this species, which makes the blackbuck stand out from the general rule of a relatively large omasum in grazing ruminants. Sand gazelles had morphological features that corresponded more to the 'moose type' or an intermediate position, although previous studies of solute and particle retention time had led to the expectation of a more 'cattle-type' anatomy. The results show that outliers to general morphological trends exist, that findings on physiology and anatomy do not always match completely and that differences in the digestive morphology among ruminant species are more difficult to demonstrate at the lower end of the body mass range.
Asunto(s)
Antílopes/anatomía & histología , Disección/veterinaria , Tracto Gastrointestinal/anatomía & histología , Omaso/anatomía & histología , Animales , Peso Corporal , Dieta , Femenino , MasculinoRESUMEN
Recent studies have shown that wild ruminants are sources of previously undescribed microorganisms, knowledge of which can improve our understanding of the complex microbial interactions in the foregut. Here, we investigated the microbial community of seven wild-caught giraffes (Giraffa camelopardalis), three of which were fed natural browse and four were fed Boskos pellets, leafy alfalfa hay, and cut savanna browse, by characterizing the 16S rRNA gene diversity using 454 FLX high-throughput sequencing. The microbial community composition varied according to diet, but differed little between the ruminal fluid and solid fraction. The giraffe rumen contained large levels of the phyla of Firmicutes and Bacteroidetes independent of diet, while Prevotella, Succinclasticium, and Methanobrevibacter accounted for the largest abundant taxonomic assigned genera. However, up to 21% of the generated sequences could not been assigned to any known bacterial phyla, and c. 70% not to genus, revealing that the giraffe rumen hosts a variety of previously undescribed bacteria.
Asunto(s)
Bacterias/clasificación , Microbiota , Rumen/microbiología , Rumiantes/microbiología , Animales , Archaea/clasificación , Archaea/genética , Archaea/aislamiento & purificación , Bacterias/genética , Bacterias/aislamiento & purificación , Bacteroidetes/genética , Bacteroidetes/aislamiento & purificación , Dieta , ARN Ribosómico 16S/genéticaRESUMEN
OBJECTIVE: To characterise the anaesthetic effects of alfaxalone administered intramuscularly (IM) at 10, 20, and 30 mg kg(-1) . STUDY DESIGN: Prospective, randomized cross-over study. ANIMALS: Ten juvenile green iguanas (Iguana iguana) of mean body weight (±SD) 480 ± 134 g. METHODS: Alfaxalone was administered IM in the triceps of both thoracic limbs. Times for anaesthetic induction, plateau and recovery periods were recorded. Skeletal muscle tone of the jaw, neck, thoracic limbs, pelvic limbs, and tail was scored. The palpebral, corneal and righting reflexes, and the response to painful stimuli were also assessed. Pulse rate and respiratory rate were recorded. Comparisons between different dosages and over time were made using anova. RESULTS: Times are given for 10, 20 and 30 mg kg(-1) dosages respectively: mean time to maximal effect was 7.7 ± 2.2, 5.4 ± 1.7 and 3.9 ± 1.2 minutes; duration of the plateau phase was 11.3 ± 3.8, 22.1 ± 6.5 and 39.1 ± 11.5 minutes; recovery time was 10 ± 2.4, 17.5 ± 8.6 and 25 ± 7.1 minutes; and total anaesthetic duration was 29 ± 35.7, 45 ± 8.2 and 68 ± 9.8 inutes. Endotracheal intubation was possible in 40% of the subjects given 10 mg kg(-1) and in 100% subjects given both 20 and 30 mg kg(-1) . Loss of response to a painful stimulus was seen in 0/10, 8/10 and 9/10 animals at 10, 20, and 30 mg kg(-1) respectively. There was an initial dose-dependent depression of respiration followed by a significant increase in frequency over time. In contrast, pulse rates decreased by 20% over the duration of the anaesthetic events. CONCLUSIONS AND CLINICAL RELEVANCE: Intramuscular administration of alfaxalone is a simple, rapid and reliable means of achieving relatively brief sedation or anaesthesia in healthy green iguanas. A dosage of 10 mg kg(-1) provides light sedation, appropriate for examination and venipuncture; 20 mg kg(-1) provides a level suitable for minor procedures or for endotracheal intubation and supplementation with inhalational anaesthesia; 30 mg kg(-1) produces an anaesthetic plane suitable for surgical procedures of limited duration (up to 40 minutes).