Search

Large- to medium-sized African ungulates are often studied in conservation areas, ignoring the fact that most African landscapes are nowadays heavily impacted by agricultural and pastoralist practices. The present study emphasises the wealth of information obtained from studying a remnant population of a medium-sized ungulate, the impala (Aepyceros melampus), on degraded rangelands in Rwanda. Compared with impala occurring under similar climatic conditions in Serengeti National Park in Tanzania, the study population showed a marked reduction in daytime activity, absence of a mid-day resting phase, and a slight increase in activity towards the late afternoon. This pattern was not directly correlated with daily variation in human activity. It is argued that hunting/poaching leads impala to seek shelter to such a degree that any daytime rhythmicity in activity patterns is lost and that increased afternoon activity reflects a shifted cost-benefit ratio of hiding versus foraging, as hungry individuals are more likely to take risks. Indeed, impala were more likely to encounter cattle herds and their herdsmen towards the afternoon. The study augments understanding of behavioural flexibility, potential for habituation and adaptation to human-induced habitat alterations in impala and highlights a possible function of rangelands as dispersal corridors for African wildlife populations.

Grazing herbivores mainly feed at low feeding height levels, while browsers select food items above ground level. Previous studies on gastrointestinal tract (GIT) nematode parasite burdens of African ungulates have suggested that browsing species hereby minimise the risk of infection with parasites. Here, we investigated the influence of feeding height levels on the pasture larval contamination level (PCL) in a natural African savannah eco-system in Queen Elizabeth National Park, western Uganda. The prevalence and mean abundance of infectious GIT nematode larvae on the pasture were used as measures of pasture contamination. Vegetation samples were examined following standard larval isolation, concentration and counting techniques. We found the feeding height level to be significantly related to the occurrence of infectious GIT nematode larvae, and the contamination was highest at low feeding levels. There was no statistically significant seasonal variation in the prevalence or mean abundance of the contamination of pastures with nematode larvae.

Summary: Grazing herbivores mainly feed at low feeding height levels, while browsers select food items above ground level. Previous studies on gastrointestinal tract (GIT) nematode parasite burdens of African ungulates have suggested that browsing species hereby minimise the risk of infection with parasites. Here, we investigated the influence of feeding height levels on the pasture larval contamination level (PCL) in a natural African savannah eco-system in Queen Elizabeth National Park, western Uganda. The prevalence and mean abundance of infectious GIT nematode larvae on the pasture were used as measures of pasture contamination. Vegetation samples were examined following standard larval isolation, concentration and counting techniques. We found the feeding height level to be significantly related to the occurrence of infectious GIT nematode larvae, and the contamination was highest at low feeding levels. There was no statistically significant seasonal variation in the prevalence or mean abundance of the contamination of pastures with nematode larvae.

During an endurance run (1000 km in 20 days) it was investigated whether an ovo-lactovegetarian diet (OLVD) could cover the nutritional requirements of endurance athletes. A regular western diet (RWD) was used as reference. Both diets were offered with an energy content of 4500 kcal per day and an energy percentage of carbohydrate:fat:protein of 60:30:10. The runners were divided into two dietary groups according to their usual dietary habits. The results of the 55 participants who completed the race show that runners from both groups had the same intake of energy, carbohydrate, fat and protein. Runners of the OLVD group consumed more dietary fiber and polyunsaturated fatty acids as well as less cholesterol. With the exception of sodium chloride and cobalamine, the intake of the calculated minerals and vitamins was higher in the OLVD and exceeded the official recommendations. This study shows that an OLVD with a high nutrient density is adequate to cover the nutritional requirements of endurance-athletes. The intake and absorption of iron should be monitored closely in all diet groups. Während eines Ausdauerlaufs (1000 km in 20 Tagen) wurde untersucht, ob eine ovo-lakto-vegetarische Kost (OLVD) den Nährstoffbedarf von Ausdauersportlern decken kann. Als Vergleichskost diente eine konventionelle Kostform (RWD). Beide Kostformen wurden mit einem Energiegehalt von 4500 kcal pro Tag und mit einem Nahrungsenergieanteil von Kohlenhydraten:Fett:Protein im Verhältnis von 60:30:10 angeboten. Die Läufer wurden — entsprechend ihrer üblichen Ernährungsgewohnheiten — in zwei Ernährungsgruppen eingeteilt. Die Ergebnisse der 55 Läufer, die das Ziel erreichten, zeigten, da\ sich Läufer aus beiden Gruppen prozentual die gleiche Menge an Nahrungsenergie, Kohlenhydraten, Fett und Protein zuführten. Läufer der ovo-lakto-vegetarischen Gruppe nahmen mehr Ballaststoffe und mehrfach ungesättigte Fettsäuren sowie weniger Cholesterin auf. Mit Ausnahme von Natriumchlorid und Cobalamin war die Aufnahme der berechneten Mineralstoffe und Vitamine in der ovo-lakto-vegetarischen Gruppe höher und überschritten die offiziellen Nährstoffempfehlungen. Diese Studie zeigt, daß eine ovo-lakto-vegetarische Kost mit einer hohen Nährstoffdichte den Nährstoffbedarf eines Ausdauersportlers angemessen decken kann. Die Zufuhr und Resorption von Eisen bedarf bei jeder Kostform einer genauen Überwachung.

Untersuchungsgegenstand sind die Veränderungen des anthropometrisch erfaßten Muskelkompartiments und seiner Beziehungen zu den korrelierenden blutchemischen und ernährungsphysiologischen Kenngrößen bei 42 Teilnehmern und 13 Teilnehmerinnen eines 1000-km-Ultralangstreckenlaufs, der in 20 Tagesetappen von jeweils 50 km zu bewältigen war. Differenziert nach Körperfraktionen folgt auf einen initialen Muskelmasseanstieg eine Abflachung bis zum 12. Tag und bleibt dann stabil. Die aktive Körpersubstanz nimmt zunächst geringfügig ab und steigt nach Laufmitte wieder an. Bei Abnahme sämtlicher korrigierter Muskeldurchmesser zeigte lediglich der Oberschenkeldurchmesser eine anabole Entwicklung, dessen hohe mechanische Belastung seinen Ausdruck im parallel erfolgenden CK- und CKMB-Anstiegen fand. Auch bei den klinischchemischen Parametern vollzieht sich die Laufadaptationsreaktion innerhalb der ersten Tage zwischen 1. und 6. Tag: Testosteron-, Kortisol- und Proteinspiegel steigen bei Laufbeginn an und fallen ab dem 3. Lauftag wieder ab, Harnstoffkonzentration und CK/CKMB-Aktivität erst ab dem 6. Tag. Die konsekutive parallele Reduktion von Harnstoff- und Harnsäurespiegeln und vielen Muskelmaßen ist möglicherweise als Clearance-Mechanismus zur Entfernung potentiell toxischer Substanzen zu verstehen. Aus den negativen Korrelationen zwischen kumulativer Proteinzufuhr und Veränderungen von Muskelmaßen sowie der katabolen Stoffwechsellage kann gefolgert werden, daß die absolute Proteinzufuhr von 1,7 g/kg Körpergewicht absolut zu erhöhen ist, um den Muskelsubstanzverlust unter Ultra-Ausdauerbelastung einzudämmen. The purpose of the study was to examine the changes of the muscle's fat-free compartment and its relation to the corresonding biochemical and nutritional parameters of 42 men and 13 women, the participants of an ultra long-distance run of 1000 km (20 days of daily running 50 km). The muscle-fractions initially increased, decreased in the middle phase, and remained stable for the rest of the run. Significant changes of the fat-free weight were registered from the 11th day on, the LBM decreasing until the middle of the distance; then the lean body mass enlarged. All the muscle-circumferences were reduced with the exception of the thigh, which grew, paralleling the CK/CKMB-concentrations, this phenomenon being due to the high mechanical stress of the lower extremities. The biochemical parameters exhibit a strain-related reaction of adaption within the initial 6 days, the hormones and protein-concentration increasing in the beginning and falling from the third day on, uric acid and CK/CKMB-activity decreasing from the 6th day on. The consecutive parallel reduction of both uric acid, urea, and muscle measurements might be seen as a special endurance-related clearance-mechanism of potential toxicants. The negative relationship between the changes of muscle measurements and the cumulative protein intake and the catabolic constellation of the clinical-chemical values might suggest that the absolute protein intake of 1.7 g/kg body mass should be increased in order to diminish the loss of musculature during an ultra-long distance run.

Male mate choice is critical for understanding the evolution and maintenance of sexual/asexual mating complexes involving sperm-dependent, gynogenetic species. Amazon mollies (Poecilia formosa) require sperm to trigger embryogenesis, but the males (e.g. Poecilia mexicana) do not contribute genes. Males benefit from mating with Amazon mollies, because such matings make males more attractive to conspecific females, but they might control the cost of such matings by providing less sperm to Amazon mollies. We examined this at the behavioural and sperm levels. P. mexicanamales preferred to mate with, and transferred more sperm to conspecific females. However, if males mated with P. formosa, sperm was readily transferred. This underscores the importance of male choice in this system.

The temp. dependence of the Paterno‐Buechi reaction between the chiral phenylglyoxylates (I) and the cyclic olefins (II) and (V) is studied.