Pygmy Hippopotamus Research Articles

A Comparison of Animal Haemoglobins using High-Performance Liquid Chromatography (HPLC)

Automated cation-exchange HPLC is now considered the cornerstone diagnostic method in many laboratories for two reasons. Firstly, unlike other methodologies it detects variant haemoglobin’s and measures haemoglobin’s A, A 2 and F percentages in a single procedure. Secondly it is suitable for larger workloads in that it is now fully automated [1-5] . Haemoglobin is most generally characterised as consisting of two α and two non- α dimers that couple to form a tetramer in certain physiological conditions. This with its own haem group in a ‘pocket’ is then formed to make up a haemoglobin molecule. This study was undertaken in order to document these different animal haemoglobin’s using HPLC in samples obtained from animal species in both the Kruger National Park and the Pretoria Zoo, with the proviso of setting up a comprehensive atlas of these particular animal haemoglobin’s, which could be used in a clinical diagnostic setting [7, 9, 16, 18] . HPLC analysis was carried out on the following adult species: Gorilla, chimpanzee, chacma baboon, vervet monkey, lion, leopard, white rhino, giraffe, wild dog, buffalo, blue and black wildebeest, Nile crocodile, eland, pigmy hippopotamus and cheetah. The findings indicated that each species had its own unique chromatogram when compared to that of humans, with regards to: Retention times (i.e. the time from application to elution from the column), their characteristic percentage and in some cases, in the shape of the peak or curve produced [6-16] . Analysis of these animal haemoglobin’s produced chromatograms with three or more significant peaks (Fig 1). Mostly these peaks corresponded to the α -globin chain, the β -globin chain and the haem unit. As confirmed in previous studies [9, 16, 17] there were some species that had as many as four distinct chromatographic peaks (Fig 2). The retention times produced from the 17 animal species examined in this study can then serve as profiles, which could be used to compile a comprehensive atlas of their unique haemoglobin chromatograms. It could also be used to identify each species where each has its own unique chromatogram. This atlas, similar to that compiled for the human haemoglobin’s [28] could then be used in a clinical setting [16] where abnormalities in the HPLC retention times may be detected if the animal is in any way compromised.

Stone age sailors: Paleolithic seafaring in the Mediterranean

Preface Chapter 1: Neanderthals Afloat: Introduction and Research Background Chapter 2: Of Boats, Invisible Sites, and Archaeological Method: Documenting Early Seafaring Activity (with K. DiBenedetto) Chapter 3: The Global Archaeology of Prehistoric Seafaring (with K. DiBenedetto) Chapter 4: Environmental Considerations (with K. DiBenedetto) Chapter 5: Early Claims for Pre-Neolithic Occupations Chapter 6: Cyprus and the Pygmy Hippo Hunters: Akrotiri Aetokremnos Chapter 7: New Developments in Cyprus Chapter 8: New Developments on Other Islands Chapter 9: Conclusions References Index About the Author

An analysis of von Economo neurons in the cerebral cortex of cetaceans, artiodactyls, and perissodactyls.

Von Economo neurons (VENs) are specialized projection neurons with a characteristic spindle-shaped soma and thick basal and apical dendrites. VENs have been described in restricted cortical regions, with their most frequent appearance in layers III and V of the anterior cingulate cortex, anterior insula, and frontopolar cortex of humans, great apes, macaque monkeys, elephants, and some cetaceans. Recently, a ubiquitous distribution of VENs was reported in various cortical areas in the pygmy hippopotamus, one of the closest living relatives of cetaceans. That finding suggested that VENs might not be unique to only a few species that possess enlarged brains. In the present analysis, we assessed the phylogenetic distribution of VENs within species representative of the superordinal clade that includes cetartiodactyls and perissodactyls, as well as afrotherians. In addition, the distribution of fork cells that are often found in close proximity to VENs was also assessed. Nissl-stained sections from the frontal pole, anterior cingulate cortex, anterior insula, and occipital pole of bowhead whale, cow, sheep, deer, horse, pig, rock hyrax, and human were examined using stereologic methods to quantify VENs and fork cells within layer V of all four cortical regions. VENs and fork cells were found in each of the species examined here with species-specific differences in distributions and densities. The present results demonstrated that VENs and fork cells were not restricted to highly encephalized or socially complex species, and their repeated emergence among distantly related species seems to represent convergent evolution of specialized pyramidal neurons. The widespread phylogenetic presence of VENs and fork cells indicates that these neuron morphologies readily emerged in response to selective forces,whose variety and nature are yet to be identified.

Hundreds of SNPs for the Endangered pygmy hippopotamus (Choeropsis liberiensis)

The pygmy hippo is an Endangered mammal endemic to West Africa, of which only 2,000–3,000 are left in the wild. Until now genetic resources to conduct monitoring of wild populations and to facilitate captive breeding have been lacking. In this study we used restriction-site associated DNA sequencing of five pygmy hippo samples to generate 1,619 high confidence candidate single nucleotide polymorphisms (SNPs) suitable for population genetic analysis. A subset of 10 of SNPs generated were validated via resequencing with 100 % success rate and through the use of KASPar DNA probes (Kbiosciences) with 90 % success rate. To facilitate future research we present the list of 1,619 SNPs ranked according to mean genotype confidence and mean coverage.

Local awareness of and attitudes towards the pygmy hippopotamusChoeropsis liberiensisin the Moa River Island Complex, Sierra Leone

AbstractThe pygmy hippopotamusChoeropsis liberiensisis an Endangered species found only in the Upper Guinea rainforests of West Africa. Using a two-phase approach, with initial semi-structured interviews followed by more extensive questionnaires, we examined local residents' awareness of and attitudes towards the pygmy hippopotamus along the Moa River near Tiwai Island Wildlife Sanctuary in Sierra Leone. The interviews and questionnaires addressed human–hippopotamus interactions, local knowledge and awareness of pygmy hippopotamus ecology and behaviour, and public attitudes towards hippopotamus conservation. Overall, 22% of questionnaire respondents acknowledged benefits related to hippopotamus conservation; factors affecting the perception of benefits included age, livestock ownership, distance from Tiwai Island and exposure to conservation programmes. The results of this study could be used to inform the conservation of the pygmy hippopotamus and highlight the critical role of local support in the management of threatened species in biodiversity hotspots.

The Cerebral Cortex of the Pygmy Hippopotamus, Hexaprotodon liberiensis (Cetartiodactyla, Hippopotamidae): MRI, Cytoarchitecture, and Neuronal Morphology

ABSTRACTThe structure of the hippopotamus brain is virtually unknown because few studies have examined more than its external morphology. In view of their semiaquatic lifestyle and phylogenetic relatedness to cetaceans, the brain of hippopotamuses represents a unique opportunity for better understanding the selective pressures that have shaped the organization of the brain during the evolutionary process of adaptation to an aquatic environment. Here we examined the histology of the cerebral cortex of the pygmy hippopotamus (Hexaprotodon liberiensis) by means of Nissl, Golgi, and calretinin (CR) immunostaining, and provide a magnetic resonance imaging (MRI) structural and volumetric dataset of the anatomy of its brain. We calculated the corpus callosum area/brain mass ratio (CCA/BM), the gyrencephalic index (GI), the cerebellar quotient (CQ), and the cerebellar index (CI). Results indicate that the cortex of H. liberiensis shares one feature exclusively with cetaceans (the lack of layer IV across the entire cerebral cortex), other features exclusively with artiodactyls (e.g., the morphologiy of CR‐immunoreactive multipolar neurons in deep cortical layers, gyrencephalic index values, hippocampus and cerebellum volumetrics), and others with at least some species of cetartiodactyls (e.g., the presence of a thick layer I, the pattern of distribution of CR‐immunoreactive neurons, the presence of von Economo neurons, clustering of layer II in the occipital cortex). The present study thus provides a comprehensive dataset of the neuroanatomy of H. liberiensis that sets the ground for future comparative studies including the larger Hippopotamus amphibius. Anat Rec, 297:670–700, 2014. © 2014 Wiley Periodicals, Inc.

First national conservation strategy for the pygmy hippopotamus in Liberia

First national conservation strategy for the pygmy hippopotamus in Liberia

No distinct stratification of ingesta particles and no distinct moisture gradient in the fore-stomach of non-ruminants: The wallaby, peccary, hippopotamus, and sloth

Herbivores that digest plant material in the fore-stomach can be divided in ruminants and non-ruminants. This study describes the distribution of feed particles (and inorganic material) and dry matter (DM) in the digestive tract of non-ruminant foregut fermenters. Results from passage trials led us to hypothesize that specific particle-sorting mechanisms, as observed in ruminants, are unlikely in non-ruminants. Therefore, no systematic particle size distribution effects (indicative of a sorting mechanism) should be evident in the fore-stomachs of these animals, but differences in fluid and particle retention suggest that differences in fluid concentration (measured as DM) could occur in the foregut of macropods and hippos. The gut content of eleven Bennett's wallabies (Macropus rufogriseus), six collared peccaries (Pecari tajacu), three pygmy hippos (Hexaprotodon liberiensis), two common hippos (Hippopotamus amphibius) and one two-toed sloth (Choloepus didactylus) were analyzed with an emphasis on the fore-stomach. The ventral and dorsal regions in sacciform compartments, and peripheral and central regions in tubular compartments, were examined. Results were not uniform across the species studied. A potential sedimentation mechanism was observed firstly by the accumulation of sand in the fore-stomach of the peccary and sloth, and secondly by the lower DM content in peripheral versus central and ventral versus dorsal regions of the fore-stomach of the wallabies and common hippos, respectively. However, pair-comparisons for different gut regions of wallabies and peccaries yielded no differences in mean particle size between fore-stomach regions. To conclude, some digesta fractionation does occur in the fore-stomach of the studied groups of non-ruminants, but not in a uniform manner, which in turn is in accordance with morphological dissimilarities of their respective foregut structures. The absence of systematic fractionation effects in non-ruminant foregut fermenters emphasizes the innovative character of the sorting mechanism in ruminants.

Why all those spines? Anachronistic defences in the Didiereoideae against now extinct lemurs

Plants evolve physical defences, such as spines, against browsing herbivores. However, in some cases, these defences may be anachronistic because the principal consumers of protected parts of the plant are extinct. In such cases, there may be few extant species consuming heavily defended resources. Here we examine the spiny defences of Madagascar’s endemic Didiereoideae, and ask whether they may be anachronistic. To accomplish this aim, we reviewed the literature to determine which species consume these plants today, and then used stable isotope biogeochemistry to determine who may have exploited Didiereoideae in the recent past. There are four major groups of browsers that are now extinct in Madagascar: giant lemurs, elephant birds (Aepyornis and Mullerornis: Aepyornithidae), pygmy hippopotamuses (Hippopotamus) and giant tortoises (Aldabrachelys: Testudinidae). Each group was evaluated for isotopic evidence of didiereoid plant consumption. Given the structure of members of this plant clade (especially Alluaudia), we predicted that lemurs would be their most important consumers. Three extant lemur species consume Didiereoideae. Several of the extinct lemurs, particularly Hadropithecus stenognathus, may have relied heavily on these spiny plants. None of the non-lemur megafaunal browsers (elephant birds, hippopotamuses and giant tortoises) were important consumers of Didiereoideae.

Male pygmy hippopotamus influence offspring sex ratio

Pre-determining fetal sex is against the random and equal opportunity that both conceptus sexes have by nature. Yet, under a wide variety of circumstances, populations shift their birth sex ratio from the expected unity. Here we show, using fluorescence in situ hybridization, that in a population of pygmy hippopotamus (Choeropsis liberiensis) with 42.5% male offspring, males bias the ratio of X- and Y-chromosome-bearing spermatozoa in their ejaculates, resulting in a 0.4337±0.0094 (mean±s.d.) proportion of Y-chromosome-bearing spermatozoa. Three alternative hypotheses for the shifted population sex ratio were compared: female counteract male, female indifferent, or male and female in agreement. We conclude that there appears little or no antagonistic sexual conflict, unexpected by prevailing theories. Our results indicate that males possess a mechanism to adjust the ratio of X- and Y-chromosome-bearing spermatozoa in the ejaculate, thereby substantially expanding currently known male options in sexual conflict.

Field surveys for the Endangered pygmy hippopotamus Choeropsis liberiensis in Sapo National Park, Liberia

AbstractConservation of a threatened species is reliant upon good quality monitoring information to provide population estimates and trends to inform management practices. Surveying to establish such data can be costly and difficult, particularly for cryptic species in forest habitats. We therefore used remotely triggered cameras to survey for the presence of the pygmy hippopotamus Choeropsis liberiensis in Sapo National Park in Liberia. In 1,247 trap days we obtained seven camera-trap photographs, the first photographic records of the species in Liberia. Habitat destruction, principally from illegal gold mining, is the greatest threat to the persistence of the pygmy hippopotamus within the Park. A range-wide survey of the pygmy hippopotamus is required to establish a robust baseline from which future conservation efforts can be developed. Understanding how this species is able to cope with the effects of habitat fragmentation across its range, and controlling commercial hunting, will dictate how it is able to survive the ongoing pressures of land conversion in West Africa.

A glance to the past: subfossils, stable isotopes, seed dispersal, and lemur species loss in Southern Madagascar

The Spiny Thicket Ecoregion (STE) of Southern and southwestern Madagascar was recently home to numerous giant lemurs and other "megafauna," including pygmy hippopotamuses, giant tortoises, elephant birds, and large euplerid carnivores. Following the arrival of humans more than 2,000 years ago, dramatic extinctions occurred. Only one-third of the lemur species which earlier occupied the STE survive today; other taxa suffered even greater losses. We use stable isotope biogeochemistry to reconstruct past diets and habitat preferences of the recently extinct lemurs of the STE. We show that the extinct lemurs occupied a wide range of niches, often distinct from those filled by coeval non-primates. Many of the now-extinct lemurs regularly exploited habitats that were drier than the gallery forests in which the remaining lemurs of this ecoregion are most often protected and studied. Most fed predominantly on C3 plants and some were likely the main dispersers of the large seeds of native C3 trees; others included CAM and/or C4 plants in their diets. These new data suggest that the recent extinctions have likely had significant ecological ramifications for the communities and ecosystems of Southern and southwestern Madagascar.

The insular cortex: a comparative perspective

The human insular cortex is involved in a variety of viscerosensory, visceromotor, and interoceptive functions, and plays a role in complex processes such as emotions, music, and language. Across mammals, the insula has considerable morphologic variability. We review the structure and connectivity of the insula in laboratory animals (mouse, domestic cat, macaque monkey), and we present original data on the morphology and cytoarchitecture of insular cortex in less common species including a large carnivore (the Atlantic walrus, Odobenus rosmarus), two artiodactyls (the pigmy hippopotamus, Hexaprotodon liberiensis, and the Western bongo, Tragelaphus eurycerus), two cetaceans (the beluga whale, Delphinapterus leucas, and the minke whale, Balaenoptera acutorostrata), and a sirenian (the Florida manatee, Trichechus manatus latirostris). The insula shows substantial variability in shape, extent, and gyral and sulcal patterns, as well as differences in laminar organization, cellular specialization, and structural association with the claustrum. Our observations reveal that the insular cortex is extremely variable among mammals. These differences could be related to the role exerted by specific and selective pressures on cortical structure during evolution. We conclude that it is not possible to identify a general model of organization for the mammalian insular cortex.

Collection and preservation of pygmy hippopotamus ( Choeropsis liberiensis) semen

Knowledge about the reproduction of the endangered pygmy hippopotamus is almost non-existent. This study takes the first step toward changing this by devising a protocol for the collection, evaluation, and short-term preservation of semen of this endangered species. Semen was collected successfully from seven bulls by electroejaculation, using a specially designed rectal probe. Mean ± SEM values of native sperm parameters from combined best fractions were: motility—80.0 ± 4.1%, concentration—2421 ± 1530 × 10 6 cells/mL, total collected cell number—759 ± 261 × 10 6 cells, intact acrosome—87.8 ± 1.2%, intact morphology—52.7 ± 4.3%, and, for some, hypoosmotic swelling test—79.3 ± 4.4% and seminal plasma osmolarity—297.5 ± 3.3 mOsm. Seven different extenders were tested for sperm storage under chilling conditions: Berliner Cryomedium (BC), Biladyl ®, modification of Kenney modified Tyrode’s medium (KMT), MES medium, Androhep ®, boar M III ™ extender and Human Sperm Refrigeration Medium. While differences between males were apparent, the BC was consistently superior to all other extenders in sperm motility and facilitated storage for 7 d with up to 30% motility and some motility even after 3 weeks. With this knowledge in hand, the obvious two directions for future research are to conduct artificial insemination and to develop a technique for sperm cryopreservation.

Hind limb myology of the common hippopotamus, Hippopotamus amphibius (Artiodactyla: Hippopotamidae)

Based on morphological traits, hippos have traditionally been classified with pigs and peccaries in the suborder Suiformes. However, molecular data indicate that hippos and cetaceans are sister taxa. This study analyses muscle characters of the common hippo hind limb in order to clarify the phylogenetic relationships and functional anatomy of hippos. Several muscles responsible for propelling the body through water are robust and display extensive fusions, including mm. semimembranosus, semitendinosus, biceps femoris and gluteus superficialis. In addition, common hippos retain long flexor and extensor tendons for each digit, reflecting the fact that all four toes are weight-bearing. These flexor tendons, together with the well-developed intrinsic muscles of the pes, serve to adduct the digits, preventing splaying of the toes when walking on soft terrain. Lastly, common hippos retain a number of primitive features, including the presence of m. articularis coxae, a well-developed m. obturator internus, superficialis and profundus tendons to all digits, mm. flexor digitorum brevis, abductor digiti V, lumbricalis IV, adductores digitorum II and V, and two mm. interossei per digit. Pygmy hippos share these features. Thus, hippopotamids retain muscles that have been lost in the majority of artiodactyls, including other suiforms. These and previously reported findings for the forelimb support the molecular data in indicating an early divergence of the Hippopotamidae from the rest of the Artiodactyla. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158, 661–682.

Polycystic Kidney Disease in the Pygmy Hippopotamus (Hexaprotodon liberiensis)

Polycystic kidney disease (PKD) was diagnosed at necropsy in a captive aged female pygmy hippopotamus (Hexaprotodon liberiensis), which presented with numerous cysts in both kidneys, the liver, and the duodenum and with one single cyst in the pancreas. There were no premonitory clinical signs of a nephropathy observed prior to its death. Similar findings were made in a male cage mate 6 mo later. Both animals had been wild caught. A literature review revealed that another seven cases of PKD have been reported in pygmy hippopotamuses, and an additional screening of records available from the international studbook for the species revealed yet another six cases. In all cases, aged females were affected, and in several instances, affected animals were related to each other. These patterns indicated familiar transmission similar that associated with PKD in humans and other animals. The disease, and especially the presumptive bias in diagnosis toward females, indicated that the male animal of this report was the first case of PKD reported in a male pygmy hippopotamus; thus, further investigation is warranted. The status of the kidneys with respect to PKD should be assessed (including histology) in every deceased pygmy hippopotamus, and whenever possible by ultrasonography in live animals.

Positive Skin and Serologic Test Results of Diagnostic Assays for Bovine Tuberculosis and Subsequent Isolation of Mycobacterium interjectum in a Pygmy Hippopotamus (Hexaprotodon liberiensis)

A 20-yr-old male pygmy hippopotamus (Hexaprotodon liberiensis), weighing 250 kg, arrived at Zoological Society London Whipsnade Zoo (United Kingdom) from a captive collection in Portugal. A quarantine health check was performed including a comparative intradermal tuberculosis (IDTB) test. Assessment of the comparative IDTB test at 72 hr revealed a strong positive reaction at the bovine site. Serum was tested with a rapid immunochromatographic assay (TB STAT-PAK) and was positive for tuberculosis antibodies. The tuberculosis tests were repeated 6 wk later with the same positive test outcome. In addition, a broncho-alveolar lavage (BAL) was submitted for mycobacterial culture. The positive IDTB test and TB STAT-PAK results were supported by multiantigen print immunoassay (MAPIA). Based on these results, the animal was suspected to be infected with Mycobacterium tuberculosis complex organisms and was euthanized. No gross or histologic signs of tuberculosis were found at postmortem examination. Mycobacterium interjectum was cultured from the BAL but not from necropsy samples. The antigens used in the TB STAT-PAK and MAPIA tests are reportedly specific for the M. tuberculosis complex, and so it is possible this animal presented with a latent case of tuberculosis or had a previous tuberculosis infection that resolved prior to testing. Cross-reactions with nontuberculous mycobacteria have been described with TB STAT-PAK and MAPIA tests. However, Western blotting analysis using serum from this animal did not recognize M. interjectum proteins of equivalent size to the M. tuberculosis-Mycobacterium bovis proteins recognized in the MAPIA. Thus, antigenic cross-reactivity with M. interjectum can be deemed less likely, but other nontuberculous mycobacterial proteins cannot be ruled out. It is therefore possible that false-positive reactions were obtained. These results highlight the difficulty of diagnosing tuberculosis in the absence of pathology and the presence of nontuberculous mycobacteria.

Looking the river Horse in the Mouth: A Reexamination of the Dentitions of the Living Hippopotami

Dentitions of the two living species of hippopotamus, Hippopotamus amphibius and Choeropsis liberiensis were reexamined with regard to tooth numbers and types, and patterns of eruption, occlusion, and replacement. Dental formulae of both species of hippo were found to have been incorrectly interpreted by previous authors. In addition to thegosis, attrition caused by foraging behavior and tongue wear was noted on the incisors. Hippos have ever‐growing incisors and canines, and selection for the presence of unusually large teeth, i. e., tooth and tooth root space, orientation and positional requirements, have shaped the anterior portion of the skull in both species, for foraging and intraspecific competition. A diastema is produced by lateral displacement of the canine and elongation of the anterior rostrum to compensate for elongation of its root in H. amphibius. The latter factor has drastically reduced the available space for the first premolar, resulting in its elimination from the adult dentition, although the deciduous first premolar often persists into adulthood. An increased time interval between successive molar eruptions in the common hippo reflects a possible adaptation to a lifespan of up to sixty years.

More efficient mastication allows increasing intake without compromising digestibility or necessitating a larger gut: Comparative feeding trials in banteng ( Bos javanicus) and pygmy hippopotamus ( Hexaprotodon liberiensis)

The digestion of plant material in mammalian herbivores basically depends on the chemical and structural composition of the diet, the mean particle size to which the forage is processed, and the ingesta retention time. These different factors can be influenced by the animal, and they can presumably compensate for each other. The pygmy hippopotamus, a non-ruminating foregut fermenter, has longer mean retention times than ruminants; however hippos do not achieve higher (fibre) digestibilities on comparable diets, which could be due to ineffective mastication. We performed feeding trials with six pygmy hippos ( Hexaprotodon liberiensis) and six banteng cattle ( Bos javanicus) on a grass diet. As predicted, both species achieved similar dry matter, organic matter, crude protein and gross energy digestibilities. However, neutral and acid detergent fibre digestibility was lower in pygmy hippos. Apparently, in these species, fibre digestibility was more influenced by particle size, which was larger in pygmy hippos compared to banteng, than by retention time. In spite of their higher relative food intake, the banteng in this study did not have greater relative gut fills than the hippos. Ruminants traditionally appear intake-limited when compared to equids, because feed particles above a certain size cannot leave the rumen. But when compared to nonruminating foregut fermenters, rumination seems to free foregut fermenters from an intrinsic food intake limitation. The higher energy intakes and metabolic rates in wild cattle compared to hippos could have life-history consequences, such as a higher relative reproductive rate.

Excretion patterns of fluid and different sized particle passage markers in banteng ( Bos javanicus) and pygmy hippopotamus ( Hexaprotodon liberiensis): Two functionally different foregut fermenters

Processing of ingesta particles plays a crucial role in the digestive physiology of herbivores. In the ruminant forestomach different sized particles are stratified into a small and a large particle fraction and only the latter is regurgitated and remasticated to smaller, easier-to-digest particles. In contrast, it has been suggested that in non-ruminating foregut fermenters, such as hippopotamuses, larger particles should be selectively excreted since they tend to be digested at a slower rate and hence can be considered intake-limiting bulk. In our study we determined the mean retention time (MRT) of fluids and different sized particles (2 mm and 10 mm) in six pygmy hippos ( Hexaprotodon liberiensis) and six banteng ( Bos javanicus) on a diet of fresh grass at two intake levels. We used cobalt ethylendiamintetraacetate (Co-EDTA) as fluid and chromium (Cr)-mordanted fibre (2 mm) and cerium (Ce)-mordanted fibre (10 mm) as particle markers, mixed in the food. Average total tract MRT for fluid, small and large particles at the high intake level was 32, 76 and 73 h in pygmy hippos and 25, 56 and 60 h in banteng, and at the low intake level 39, 109, and 105 h in pygmy hippos and 22, 51 and 58 h in banteng, respectively. In accordance with the prediction, large particles moved faster than, or as fast as the small particles, through the gut of pygmy hippos. In contrast, large particles were excreted slower than the small particles in the ruminant of this study, the banteng. Pygmy hippos had longer retention times than the banteng, which probably compensate for the less efficient particle size reduction. Although the results were not as distinct as expected, most likely due to the fact that ingestive mastication of the larger particle marker could not be prevented, they confirm our hypothesis of a functional difference in selective particle retention between ruminating and non-ruminating foregut fermenters.