SUMMARYThe study was carried out in northern Kenya in 1984–87. Forestomach volumes and digesta retention times were measured using Cr-EDTA or Co-EDTA as fluid markers and Ce-labelled particles or Cr-mordanted particles as paniculate phase markers.Mean retention times of fluid and of particles were longer in the dry season than in the green season in all four animal species. The increase of particle mean retention time, as a percentage of the values in the green season, was highest in sheep (46%), followed by cattle (27%), goats (22%) and camels(18%). Forestomach volumes were also greater in the dry than in the green season; the increase was again highest in sheep (55%), followed by cattle (31%), goats (29%) and camels (28%). Outflow rates of fluid from the forestomach and the selectivity factor, by which small particles were retained longer in the forestomach than fluid, did not differ significantly between the seasons.It is suggested that the increase of forestomach volumes is an effective adaptation to dry-season pasture conditions. It enables the animals to retain feed particles longer in the forestomach and so improve fibre digestion when feed quality is low. Cattle and sheep, which depend on a poor quality diet, improve fibre digestion in this way in the dry season more effectively than camels and goats. Camels and goats, on the other hand, were able to select a diet of such quality, even in the dry season, that their need to augment fibre digestion was reduced.
A population-based study was carried out on the Ankole ranching scheme in south-west Uganda with the aim of determining the endemic status of Theileria parva infections. For this purpose, the age-related sero-prevalence of T. parva and the specific calf mortality associated with the parasite were assessed. Blood samples were collected from 931 Ankole calves of up to 12 months of age from 81 randomly selected herds. The relationship between rainfall pattern and whole-body Rhipicephalus appendiculatus counts was determined. The influence of tick control practices on East Coast fever-related calf mortality, and sero-positivity were also determined. A significant (r2 = 0.76, P = 0.000) association between R. appendiculatus counts and rainfall was observed. There was no significant (P > 0.05) association between theileriosis- related calf mortality, sero-positivity and the different tick control practices. Antibody prevalence based on the PIM ELISA was above 70 % among calves of 6 months of age in 96 % in all the herds. Theileria parva-related calf mortality determined by repeated herd visits and farm records ranged between 0% and 5.4 %. It was concluded that endemic stability for theileriosis, caused by T. parva, existed in the study area, and that the risk of the occurrence of economically important outbreaks of East Coast fever in indigenous cattle was regarded as minimal under the prevailing conditions.
Zusammenfassung
Der wasserlösliche Anteil verschiedener, von einheimischen Wiederkäuern, Kamelen und Eseln bevorzugten Futterpflanzen aus der Dornbuschsavanne Kenyas wurde untersucht.
Der Gehalt an löslichem Zucker, Stärke, Pektinen, Rohprotein und Mineralien wurde bestimmt.
Der mittlere wasserlösliche Anteil der Pflanzen betrug zwischen 5% und 50% der Trockenmasse. Monocotyledonen hatten einen geringeren wasserlöslichen Anteil als Dicotyledonen. Der wasserlösliche Anteil der Monocotyledonen war in der Regenzeit größer (24,8%) als in der Trockenzeit (19,2%; p < 0,001). Pflanzen hoher Verdaulichkeit hatten einen größeren wasserlöslichen Anteil als Pflanzen mittlerer und geringer Verdaulichkeit.
Lösliche Zucker bilden den größten Anteil der löslichen Substanz in den Pflanzen, gefolgt von Pektinen. Proteine bilden den kleinsten Anteil der löslichen Substanz bei Pflanzen hoher und mittlerer Verdaulichkeit. Mineralische Bestandteile bildeten den kleinsten Anteil bei Pflanzen geringer Verdaulichkeit.
Trotz der großen Unterschiede in der Menge des löslichen Anteils scheinen die Proportionen der einzelnen chemischen Bestandteile recht konstant. Kohlenhydrate bilden dabei mit 75% der Trockensubstanz den größten Anteil.
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