Fluid and particle retention in the digestive tract of the addax antelope (Addax nasomaculatus)--adaptations of a grazing desert ruminant

Retention time of food in the digestive tract is a major aspect describing the digestive physiology of herbivores. Differences in feed retention times have been described for different ruminant feeding types. In this study, a dominantly grazing desert ruminant, the addax (Addax nasomaculatus), was investigated in this respect. Eight animals with a body weight (BW) of 87+/-5.3 kg on an ad libitum grass hay (Chloris gayana) diet were available. Co-EDTA and Cr-mordanted fibers (<2 mm) were used as pulse-dose markers. Mean retention time (MRT) in the digestive tract was calculated from faecal marker excretion. Average daily intake of the addax was found to be 1.7 kg dry matter (DM) or 60+/-8.3 g DM/kg BW(0.75). The MRT of fluid and particles in the reticulo-rumen (MRT(fluid)RR and MRT(particle)RR) were quantified to be 20+/-5.8 and 42+/-7.0 h respectively. When compared to literature data, MRT(fluid)RR was significantly longer than in cattle species, and MRT(particle)RR was significantly longer than in 11 taxa of all feeding types. The ratio of MRT(particle)RR/MRT(fluid)RR (2.3+/-0.5) was found to be within the range described for grazing ruminants. The long retention times found in the addax can be interpreted as an adaptation to a diet including a high proportion of slow fermenting grasses, while the long retention time of the fluid phase can be interpreted as a consequence of water saving mechanisms of the desert-adapted addax with a potentially low water turnover and capacious water storing rumen.     

Artificial insemination with frozen,thawed semen and pregnancy diagnosis in addax (Addax nasomaculatus)

Nonsurgical artificial insemination (AI) procedures were performed using frozen, thawed semen in two adult female addax. Pregnant mares' serum gonadotropin (PMSG) (300 IU) and prostaglandin (PG) (125 μg) was administered intramuscularly to female 1 on days ?3 and ?1, respectively, where day 1 was the first day of AI. Only one injection of PG was used, as a low serum progesterone (PROG) concentration (0.5 ng/ml) and a low pregnanediol glucuronide (PdG) concentration (0.36 ng PdG/mg creatinine) had been recorded on day ?13. A total of 219 × 10⁶ motile sperm was deposited in the os cervix or anterior vagina on days 1–4. High serum PROG levels (9.4–15.8 ng/ml) and high urinary PdG levels (1.35–1.63 ng PdG/mg creatinine) were observed on days 23, 31, and 39, and the fetal heart was seen beating during an ultrasound exam on day 45. A male calf was born on day 266, 8.7 mo after insemination. This is the first live birth resulting from AI of an antelope with frozen, thawed semen. The Synchro-mate-B system of estrous control was used in female 2. The implant was inserted, and the injection was given on day ?11 per the manufacturer's instructions. The implant was removed on day ?1, and a total of 220 × 10⁶ motile sperm was deposited in the os cervix or anterior vagina on days 1 and 2. High serum PROG levels (17.5–24.5 ng/ml) were observed on days 13, 21, and 29. Although the fetal heartbeat was observed during an ultrasound examinataion on day 42, the fetus was not carried to term. Details of the radioimmunoassay used to determine the luteinizing hormone immunoreactivity of urine samples are presented.     

Genetic structure analysis of a highly inbred captive population of the African antelope Addax nasomaculatus. Conservation and management implications

The African antelope Addax nasomaculatus is a rare mammal at high risk of extinction, with no more than 300 individuals in the wild and 1,700 captive animals distributed in zoos around the world. In this work, we combine genetic data and genealogical information to assess the structure and genetic diversity of a captive population located at Parque Lecocq Zoo (N=27), originated from only two founders. We amplified 39 microsatellites previously described in other Artiodactyls but new to this species. Seventeen markers were polymorphic, with 2–4 alleles per locus (mean=2.71). Mean expected heterozygosity (He) per locus was between 0.050 (marker ETH3) and 0.650 (marker D5S2), with a global He of 0.43. The mean inbreeding coefficient of the population computed from pedigree records of all registered individuals (N=53) was 0.222. The mean coancestry of the population was 0.298 and F_IS index was ?0.108. These results reflect the importance of an adequate breeding management on a severely bottlenecked captive population, which would benefit by the incorporation of unrelated individuals. Thanks to the successful amplification of a large number of microsatellites commonly used in domestic bovids, this study will provide useful information for the management of this population and serve as future reference for similar studies in other captive populations of this species. Zoo Biol 30:399–411, 2011. © 2010 Wiley‐Liss, Inc.     

Correction to: The environment matters: season and female contact affect the behavior of captive Addax nasomaculatus male antelope

The addax antelope (Addax nasomaculatus) is a species under serious threat of extinction, as it is more abundant in captivity than in the wild. However, little is known about its basic biology. The aims of this study were to determine how locomotor, feeding, aggressive, marking, and sexual behavior of male addax allocated in all-male groups vary with season and with female contact (i.e., biostimulation). The study was conducted in captive conditions, in two groups of adult males: one with no-physical contact with females, aside from visual and olfactory interactions (CF group, n = 4), and another group completely isolated from females (IF group, n = 4). The frequency of behaviors was recorded during the daytime, 4 days per season (total time of observation = 256 h). Lying, standing, walking, aggressive, marking, grazing, and ruminating behaviors as well as water and supplement consumptions varied with season (all p < 0.05). The lying, walking, marking, grazing, and ruminating behaviors were more frequently observed for CF than IF males (all p < 0.05). Also, all behaviors, except for marking, varied with the interaction between the group and seasons (all p < 0.05). Sexual behavior was extremely scarce, so it was not possible to analyze how it varied with seasons and the group. The present study suggests that management program and housing conditions, especially in ex situ breeding plans, should consider the influence of the season and the sociosexual context on the behavior of addax males.

     

Solute and particle retention in the digestive tract of the Phillip's dikdik (Madoqua saltiana phillipsi), a very small browsing ruminant: biological and methodological implications

Morphological characteristics of the forestomach, as well as reports of a natural diet that mostly excludes monocots, suggest that dikdiks (Madoqua spp.), among smallest extant ruminants, should have a 'moose-type' forestomach physiology characterised by a low degree of selective particle retention. We tested this assumption in a series of feeding experiments with 12 adult Phillip's dikdiks (Madoqua saltiana phillipsi) on three different intake levels per animal, using cobalt-EDTA as a solute marker and a 'conventional' chromium-mordanted fibre (<2 mm; mean particle size 0.63 mm) marker for the particle phase. Body mass had no influence on retention measurements, whereas food intake level clearly had. Drinking water intake was not related to the retention of the solute marker. In contrast to our expectations, the particle marker was retained distinctively longer than the solute marker. Comparisons with results in larger ruminants and with faecal particle sizes measured in dikdiks suggested that in these small animals, the chosen particle marker was above the critical size threshold, above which particle delay in the forestomach is not only due to selective particle retention (as compared to fluids), but additionally due to the ruminal particle sorting mechanism that retains particles above this threshold longer than particles below this threshold. A second study with a similar marker of a lower mean particle size (0.17 mm, which is below the faecal particle size reported for dikdiks) resulted in particle and fluid retention patterns similar to those documented in other 'moose-type' ruminants. Nevertheless, even this smaller particle marker yielded retention times that were longer than those predicted by allometric equations based on quarter-power scaling, providing further support for observations that small ruminants generally achieve longer retention times and higher digestive efficiencies than expected based on their body size.     

Melengestrol acetate implant contraception in addax (Addax Nasomaculatus) and Arabian oryx (Oryx Leucoryx)

Melengestrol acetate (MGA) implants were used for contraception in three addax and three Arabian oryx females housed at the Saint Louis Zoo. Serum estradiol and progesterone or fecal estrogen and progestin analysis and ultrasonography of reproductive tracts were used for monitoring changes before, during, and after MGA treatment. Follicular development and irregular uterine fluid accumulation were detected in all females during MGA treatment. Although housed with an intact male for all or most of the contraceptive period, no pregnancies occurred. One female addax may have ovulated, based on sustained elevated progesterone levels, and another showed continued follicle development, as seen by fluctuating estradiol concentrations. Reversibility was documented in two of the three addax that resumed reproductive cycles post‐MGA‐implant removal, whereas the third, a peripubertal female, did not cycle before, during, or after treatment. Addax females were lost to further follow‐up after transfer to another institution, so the possibility of subsequent pregnancies is not known. All three Arabian oryx ovulated during the initial MGA treatment, but two of the three females had implants past the typical 2‐year efficacy period. They had regular ovulatory cycles after implant removal, with mean cycle length of 27.5±1.5 days and mean luteal phase duration of 15.2±0.7 days. Reversibility was further shown in all three oryx by pregnancies after placement with a male approximately 2 years after MGA implant removal. Two produced healthy calves, but the third died owing to an unrelated terminal illness in the mother. Zoo Biol 26:299–310, 2007. © 2007 Wiley‐Liss, Inc.     

Physical characteristics of rumen contents in four large ruminants of different feeding type,the addax (Addax nasomaculatus), bison (Bison bison), red deer (Cervus elaphus) and moose (Alces alces)

Based on morphological and physiological observations, it has been suggested that differences exist in the degree that reticuloruminal (RR) contents are stratified between various ruminant species. However, the occurrence of stratification has hardly been measured in non-domestic species. Forestomach contents of free-ranging moose (n = 22) and red deer (24) shot during regular hunting procedures, and of captive (but 100% forage fed) addax (6) and bison (10) culled for commercial or management purposes were investigated. There was no difference between the species in the degree by which RR ingesta separated according to size due to buoyancy characteristics in vitro. However, RR fluid of moose was more viscous than that of the other species, and no difference in moisture content was evident between the dorsal and the ventral rumen in moose, in contrast to the other species. Hence, the RR milieu in moose appears less favourable for gas or particle separation due to buoyancy characteristics. These findings are in accord with notable differences in RR papillation between the species. In moose, particle separation is most likely restricted to the reticulum, whereas in the other species, the whole rumen may pre-sort particles in varying degrees; a possible explanation for this pattern is a hypothetically lesser saliva production and fluid throughput in moose. The results suggest that differences in RR physiology may occur across ruminant species. The RR sorting mechanism should be considered a dynamic process that is better measured by its result — the significantly smaller particle size in the distal digestive tract when compared to the RR — than by regional differences in particle size within the RR.     

Comparisons among selected neonatal biomedical parameters of four species of semi-free ranging Hippotragini: Addax (Addax nasomaculatus), scimitar-horned oryx (Oryx dammah), Arabian oryx (Oryx leucoryx), and sable antelope (Hippotragus niger)

Basic biomedical data from 164 neonates of four species of the tribe Hippotragini, addax (Addax nasomaculatus), scimitar-horned oryx (Oryx dammah), Arabian oryx (Oryx leucoryx), and sable antelope (Hippotragus niger), were compared at one zoological institution over a 9-year period. Measured biomedical parameters included body weight, temperature, pulse and respiratory rates, packed cell volume (PCV), total plasma protein, glucose, IgG assessment via zinc sulfate turbidity, and white blood cell count with differential. All species were maintained in a semi-free ranging setting with the same diet, available shelter, and opportunity for social interaction. Based on clinical and field observations, all neonates used in the study were believed to be at least 24 hr old, to have bonded with the dam, and to have no obvious physical abnormalities. Median body weights were similar only in the addax and Arabian oryx with sable antelope having the largest median body weight. No significant differences in rectal temperatures or pulse rates were found among species. Median respiratory rates were similar between certain groups. Arabian oryx and scimitar-horned oryx shared the highest packed cell volumes while the sable antelope had the lowest. Sable antelope had the highest median total plasma protein with no significant differences among the other species. Sable were also significantly lower in median blood glucose than the three other Hippotraginae. Zinc sulfate turbidities in all species were similar. Addax had higher median total white blood cell counts than sable. No significant differences in the median numbers of segmented neutrophils, band neutrophils, and eosinophils were detected among species. Basophils were only found in the scimitar-horned oryx in one animal. Addax had higher median lymphocyte counts than sable and Arabian oryx as well as higher median monocyte counts than sable. All four species exhibited higher median counts of neutrophils compared with lymphocytes. The biomedical differences observed highlight the importance of having an accurate database of clinical normal values against which to evaluate neonatal health. Zoo Biol 20:47-54, 2001. Copyright 2001 Wiley-Liss, Inc.     

Temporal patterns in natality and mortality of three threatened antelope species in North Africa: Oryx dammah,Addax nasomaculatus and Nanger dama

Long‐term population studies on large mammals are rare. Here, we have examined the threatened scimitar‐horned oryx, addax and dama gazelle's populations over the last 20 years in Bou Hedma National Park. Using monthly count data of the three studied species collected since 1995, we examined their population trends. Using autocorrelation analyses, we discovered endogenous natural cyclical fluctuations in the numbers of each species, with a periodicity of approximately 3 years. For all three studied species which seem to be opportunistic breeders, births and deaths occurred throughout the year, although with notable seasonality. By means of cross‐correlation, we discovered that during the first 7 years for which data were available, addax numbers were positively correlated with those of dama and inversely correlated with numbers of oryx. This pattern reversed during the following 4‐year period. The number of oryx was negatively correlated with dama during the first 4 years and then became positively correlated during the subsequent 7‐year period. Thus, we draw attention to difference in response to environmental and anthropogenic factors. Incorporating fundamental long‐term population data into developing management approaches, especially for potentially competitive species, is vital for their future long‐term survival and the success of conservation actions.     

Fluid and particle retention in captive okapi (Okapia johnstoni)

Retention time of food in the digestive tract is among the key variables that describe the digestive strategy of a herbivore. Mean retention time (MRT) was measured on 4 captive specimens of the okapi, a strictly browsing ruminant. Retention time was quantified on different diets, using Co-EDTA (fluid phase) and Cr-mordanted fibres (1–2 mm) (particle phase) as pulse-fed markers. Average food intake was 55–65 g DM/(kg BW^0.75*d). Fecal excretion of the markers was quantified over 10 days. Different models to calculate retention time and passage rate in the gastrointestinal tract (GIT) and the reticulorumen (RR) were applied. Average MRT_particleGIT was quantified to be 47 ± 8 h and MRT_fluidGIT 36 ± 5 h. Concerning estimation of retention times in the reticulorumen, MRT_particleRR was quantified to be 27 ± 7 h, while MRT_fluidRR was 17 ± 4 h. The quotients MRT_particle/MRT_fluid were quantified to be 1.3 ± 0.1 for the GIT and 1.6 ± 0.2 for the RR. Compared to data established with comparable markers, the okapi has low coefficients of MRT_particle/MRT_fluid. A less well developed retention mechanism for fibres compared to species like cattle or sheep can be explained by a comparatively high fermentation rate and low digestibility of the natural food of the okapi—browse—in comparison to grass.     

Digesta passage and functional anatomy of the digestive tract in the desert tortoise (Xerobates agassizii)

The herbivorous tortoise Xerobates agassizii contents with large fluctuations in the quality and abundance of desert pastures. Responses to grass (Schismus barbatus), herbage (Sphaeralcea ambigua) and pelleted diets were studied in captive animals. Digestive anatomy was investigated in wild tortoises. Cornified esophageal epithelia and numerous mucus glands along the digestive tract indicated a resistance to abrasive diets. Gastric contents were acidic whereas hindgut digesta were near neutral pH. The colon was the primary site of fermentation with short-chain fatty acids mainly comprised of acetate (69–84%), propionate (10–15%) and n-butyrate (1–12%). Fibre digestion was extensive and equivalent to 22–64% of digestible energy intakes. Large particles of grass (25 mm Crmordants) were excreted as a pulse but retained longer than either fluids (Co-EDTA) or fine particles (2 mm; Yb). Patterns of marker excretion suggested irregular mixing of only the fluid and fine particulate digesta in the stomach and the colon. Mean retention times of Crmordants were 14.2–14.8 days on the grass and highfibre pellets. Intakes of grass were low and accompanied by smaller estimates of digesta fill than for the high-fibre pellets. Digestive capacity was large and estimated at 11–21% of body mass on these diets. The capacious but simple digestive anatomy of the tortoise may provide the greatest flexibility in utilizing a variety of forages in its unreliable habitat.Abbreviations bm body mass - DM drymatter - EDTA ethylene-diamine tetra-acetic acid - MRT mean retention time - NDF neutral detergent fibre - SCFA short-chain fatty acid(s) - T _max time to maximum marker concentration     

Fluid and particle retention times in the black rhinocerosDiceros bicornis, a large hindgut-fermenting browser

The mean retention time (MRT) of ingesta in the gastrointestinal tract is one of the major determinants of herbivore digestive physiology. We examined MRTs of fluids and particles in the gastrointestinal tract of six adult captive black rhinocerosesDiceros bicornis on conventional zoo diets. Fluid MRT ranged from 25–45 h and averaged 31 h. Particle MRT ranged from 28–59 h and averaged 38 h. In the six animals, both fluid and particle MRT declined as relative dry matter intake (g/kg metabolic body mass) increased. Black rhinoceroses, which are large hindgut-fermenting browsers, retained ingesta for a shorter period relative to their body size than grazing equids or grazing rhinoceros species. Our findings support the hypothesis that browsing hindgut fermenters have relatively shorter MRTs than grazing hindgut fermenters.     

Response of the ruminant respiratory tract to Mannheimia (Pasteurella) haemolytica

Pneumonia is a leading cause of loss to the sheep and cattle industry throughout the world. Mannheimia (Pasteurella) haemolytica is one of the most important respiratory pathogens of domestic ruminants and causes serious outbreaks of acute pneumonia in neonatal, weaned and growing lambs, calves, and goats. M. haemolytica is also an important cause of pneumonia in adult animals. Transportation, viral infections with agents such as infectious bovine rhinotracheitis virus, parainfluenza-3 virus or bovine respiratory syncytial virus, overcrowding, housing of neonates and weaned animals together and other stressful conditions predispose animals to M. haemolytica infection [1, 2]. This review assimilates some of the findings key to cellular and molecular responses of the lung from a pathologist's perspective. It includes some of what is known and underscores areas that are not fully understood.     

Ultrastructure of the digestive tract in Acarus siro (Acari: Acaridida)

The gut of the mite Acarus siro is characterized on the ultrastructural level. It consists of the foregut (pharynx, esophagus), midgut (ventriculus, caeca, colon, intercolon, postcolonic diverticula, postcolon), and hindgut (anal atrium). The gut wall is formed by a single-layered epithelium; only regenerative cells are located basally and these have no contact with the lumen. Eight cell types form the whole gut: (i) simple epithelial cells forming fore- and hindgut; (ii) cells that probably produce the peritrophic membrane; (iii) regenerative cells occurring in the ventriculus, caeca, colon, and intercolon; (iv) spherite cells and (v) digestive cells forming the ventriculus and caeca; (vi) colonic cells and (vii) intercolonic cells; and (viii) cells forming the walls of postcolonic diverticula and postcolon. Spherite and digestive cells change in structure during secretory cycles, which are described and discussed. The cycle of spherite, colonic, and intercolonic cells is terminated by apoptosis. Ingested food is packed into a food bolus surrounded by a single homogeneous peritrophic membrane formed by addition of lamellae that subsequently fuse together. The postcolonic diverticula serve as a shelter for filamentous bacteria, which also are abundant in the intercolon.     

Retention of fluid and particles in the digestive tract of the llama (Lama guanacoe f. glama)

The retention times of fluid and particles of different lengths were measured in the digestive tract of the llama. PEG was used as a fluid marker; hay particles were labelled with cerium or samarium and the samples were determined by neutron activation analysis. In compartments 1 and 2 the retention time of fluid (9.7 hr) was significantly shorter than that of particles having a length of 0.2-1.0 cm (19.2 hr) and 2.5-4.0 cm (25.0 hr). In the intestine slightly significant differences in the retention times of fluid (20.1 hr) and particles (26.2 hr) were seen. In the whole digestive tract retention times were 36.2 hr for fluid, 52.0 hr for smaller particles and 59.9 hr for larger particles.     

Structure of the digestive tract of tornaria larva inEnteropneusta (Hemichordata)

The ultrastructure of the digestive tract of tornaria larva of enteropneusts was investigated. It showed that the digestive tract consists of three parts: esophagus, stomach, and intestine. The esophagus epithelium consists of two types of multiciliated epithelial cells and solitary muscle cells. Axonal tracts and neurons were found in the ventral wall of the esophagus. The cardiac sphincter contains an anterior band of strongly ciliated cells and a posterior band of cells with long vacuolized processes which partition the sphincter lumen. The stomach consists of three cell types: (1) cells with electron-opaque cytoplasm, bearing a fringed border on their apical sides; (2, 3) sparse cells with electron-light cytoplasm and different patterns of apical microvilli. Cells of the pyloric sphincter bear numerous cilia and almost no microvilli. The intestine consists of three parts. The anterior part is formed of multiciliated cells which bear the fringed border. The middle part consists of flattened cells bearing rare cilia and vast numbers of mace-like microvilli. The posterior part of the intestine is formed of cells bearing numerous cilia and few microvilli. Muscle cells were not found in either stomach or intestine epithelium. One noticed that the structure of the digestive tract of enteropneust tornaria larva differs from that of echinoid pluteus larva.