A study to determine the physiological and biochemical responses of eight tea Camellia sinensis (L.) O. Kuntze cultivars to water-deficit stress was conducted in a ‘rain-out shelter’ using potted ...plants. Three levels of soil moisture content 34, 26, or 18% (v/v) water were applied to three plants of each cultivar in a complete randomised design, and the whole experiment was replicated three-times. The treatments were applied for 12 weeks, during which time plant water status, shoot extension rates, changes in gas exchange parameters, and leaf proline and glycinebetaine concentrations were determined. The imposition of severe water-deficit conditions 18% (v/v) soil water content caused a significant (P ≤ 0.05) decline in the relative water content of leaves, shoot water potentials, and shoot extension rates from mean values of 84.8% to 50.6%, –0.80 to –1.15MPa, and 1.87 to 0.29 mm d–1, respectively, compared to plants grown in a well-watered soil 34% (v/v) soil water content. The three gas exchange parameters measured (stomatal conductance, evapotranspiration rate, and rate of net photosynthesis) also declined significantly (P ≤ 0.05) with decreasing soil moisture content. In contrast, water-deficit stress increased the accumulation of leaf proline and glycinebetaine from mean values of 0.104 to 0.244 μmol g–1 FW, and from 1.567 to 2.025 μmol g–1 DW, respectively. The eight tea cultivars differed significantly (P ≤ 0.05) in their responses to water-deficit stress. Proline accumulation was significantly (P ≤ 0.05) higher in the drought-tolerant cultivars, ‘TRFK 306’, ‘TRFCA SFS150’, and ‘EPK TN14/3’, suggesting that proline concentration could be used as a marker for drought-tolerance in tea.
African trypanosomes of the subgenera Nannomonas and Pycnomonas have been recorded from both wild and domestic suids. However, complete descriptions of some of these trypanosomes with regard to host ...range, pathogenicity, transmission and distribution are still lacking. Neither the recently described Trypanosoma (Nannomonas) godfreyi nor Trypanosoma (Nannomonas) congolense Tsavo have been isolated from mammalian hosts, while Trypanosoma (Pycnomonas) suis remains the rarest of the Salivarian trypanosomes. The only isolate presumed to be of the latter species is maintained at the Kenya Trypanosomiasis Research Institute, Nairobi. We present here the results of characterization of this isolate by morphology, tsetse transmission, the use of species-specific DNA probes and DNA sequence analysis. Morphology in stained blood smears revealed a small trypanosome with a free flagellum. Experimental transmission through Glossina morsitans morsitans showed a developmental cycle typical of subgenus Nannomonas A positive identification was obtained with species-specific PCR primers for T. congolense Tsavo; moreover, the sequence of the SSU rRNA gene was almost identical to that of T. congolense Tsavo on database. In phylogenetic analysis of the SSU rRNA genes of Salivarian trypanosomes, T. congolense Tsavo grouped with T. simiae rather than T. congolense, suggesting that the name T. simiae Tsavo is more appropriate.
Information was collected on the use of veterinary drugs by Maasai pastoralists in an area of Kenya where tsetse flies and trypanosomosis occur. Three herds of cattle were followed for between 4 and ...5 years and records were kept of every veterinary drug treatment given by the livestock owners. Almost all treatments were either with the trypanocides homidium or diminazene, or with oxytetracycline by intramuscular injection. The rate of trypanocide use varied between 0.66 and 1.56 treatments per animal per year, while oxytetracycline use was between 0.20 and 1.00 treatments per animal per year. Farmers were injecting these drugs in the absence of veterinary supervision, obtaining their supplies mainly from local village shops or informal traders. Underdosing with trypanocides appeared to be uncommon and the indications were that farmers generally gave the drugs at dosage rates above the recommended standard dose. Accurate information on the dose rates of oxytetracycline could not be obtained, but it was noted that in most cases farmers gave a single injection rather than a course of treatment. In a proportion of cases, trypanocides and antibiotics were mixed together before injection. The farmers administered the drugs when disease was recognized and were rarely using trypanocides as prophylactics. Although necessity forces the livestock owners to obtain and use these drugs without veterinary supervision, there are concerns with regard to the possibility of drug misuse and the development of drug resistance.
A sampling system was devised and used from 1992 to 1996 in annual grassland and open woodland of the south‐west Kenyan Rift Valley. The monitoring was designed to detect vegetation changes ...consequent on the attempted removal of the tsetse vectors of trypanosomiasis in cattle during a simultaneous trapping programme. The sampled sites covered most vegetation‐landscape types, and have led to a better understanding of processes within some. Although fluctuations in pastoralist use and occupancy have been observed, no change in vegetation can be attributed to increased grazing or browsing. Although there is high climatic variability some vegetation types seemed stable over the period studied, and some trends appear to be predictable.
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On a conçu un système d'échantillonnage qui fut utilisé de 1992 à 1996 dans les prairies annuelles et dans les forêts ouvertes du sud‐ouest de la Rift Valley, au Kenya. La surveillance était conçue de façon à détecter les changements de végétation qui résultaient des tentatives d'éradication des mouches tsé‐tsé, vecteurs de la trypanosomiase chez le bétail, au cours d'un programme de piégeage. Les sites d'échantillonnages couvraient des paysages correspondant à la plupart des types de végétation et ont conduit à une meilleure compréhension du processus dans certains d'entre eux. Bien qu'on ait observé des fluctuations dans l'occupation et l'utilisation pastorales, on ne peut attribuer aucun changement de végétation à une augmentation du pâturage. Bien que le climat soit très variable, certains types de végétations semblent être restés stables pendant la durée de l'étude et l'on semble pouvoir prédire certaines tendances.
The trypanocidal activity of two commercially available isometamidium-based products, Samorin® (Merial, USA) and Veridium® (Sanofi Santé Nutrition Animale, France), used at a dose rate of 0.5 mg kg
...−1 bodyweight, was compared in a field trial involving groups of approximately 30 zebu cattle in a trypanosomosis endemic part of south-western Kenya. The trial took place between April 1997 and March 1998 during a time of higher than normal rainfall that resulted in periods of high trypanosome challenge. The trial consisted of five consecutive prophylactic cycles, each of approximately 10 weeks duration. It was demonstrated that there was no significant difference in the prophylactic activity of the two isometamidium-based products, and no significant difference between the relative activity of three different batches of the product Veridium® used during the course of the trial. There was some evidence that drug-resistant strains of trypanosomes may have been present, but it was concluded that isometamidium is still an effective trypanocidal drug in this location.
Rising feed cost challenges due to expensive conventional protein sources continue to make headlines in Africa causing drops in profit margins. We assessed the impact of insect (Hermetia illucens ...Linnaeus larvae meal, HILM) protein as a substitute for soybean meal and sunflower seed cake on layer chicken performance and profitability. Our results showed that apart from the growers, chicks (12.37 g/bird) and layer hens (2.02 g/bird) fed diets with 75% HILM inclusion levels had significantly higher average daily weight gain. The average daily feed intake (ADFI) and feed conversion ratio (FCR) varied significantly when the chicks and layer hens were provided with the HILM-based diets. For the chicks and layer hens, the lowest ADFI and FCR were observed in birds subjected to diets with 75% and 100% HILM compared to the growers fed diets with 50% HILM. Significantly higher egg production was observed for layer hens fed diets containing 75% of HILM throughout the first (87.41%) and second (83.05%) phase production cycles. Layer hens fed HILM-based diets had a 3–10% increase in egg laying percentage. There was higher profit margins when birds were fed diets containing 75% of HILM (∼1.83 and 5.98 US$ per bird), which mirrored the return on investment estimated at 63.95% and 33.36% for the pullets (growers) and laying hen, respectively. Our findings demonstrate that diets with 75% HILM provided optimum growth performance, reduced feeding costs, increased weight gain and egg production as well as improved economic returns for commercial on-farm poultry production systems.
Presents the Orma Boran field observations carried out under tsetse fly challenge on Galana ranch in Kenya since 1980. Their response to trypanosomiasis has been compared to that of the ranch bred ...Kenya (Galana) Boran. The mean monthly prevalence of trypanosomiasis observed in Orma steers over five years was 17 percent compared with 31 percent in the Galana Borans. Mean annual mortality over five years was 35 percent in untreated Orma steers compared with 71 percent in untreated Galana steers. The primary difference appeared to be in their response to Trypanosoma vivax challenge. Their ability to acquire resistance has also been investigated under field conditions and both acquired and innate resistance appear to play a role. Steers monitored weekly over two years and treated with diminazene aceturate immediately on detection of infection showed some evidence of improved control of anaemia. In contrast, steers treated only when the PCV fell to 15 percent showed little evidence of improved anaemia control over two years. There was strong evidence for an innate component and the repeatabilities of PCV and infection rate were significant between the two years. Orma calves born on Galana ranch and herded together with their Galana counterparts were detected parasitaemic less often and the pre-weaning mortality was 7 percent compared with 17 percent for the Galana calves. The trypanosome prevalence in both groups of calves was lower than that observed over the same period in their dams and the vivax ratio was higher. Orma calves, however, had significantly lower birth & weaning weights than their Galana counterparts.
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