Geologic exploration of taurus-littrow: apollo 17 landing site

Apollo 17 landed in a deep graben valley embaying the mountainous highlands southeast of the Serenitatis basin. Impact-generated breccias underlie the massifs adjacent to the valley, and basalt has flooded and leveled the valley floor. The dark mantle inferred from orbital photographs was not recognized as a discrete unit; the unusually thick regolith of the valley floor contains a unique high concentration of dark glass beads that may cause the low albedo of much of the surface.     

Epidemiological observations on theileriosis following field immunisation using infection and treatment

Thirty-seven high grade cattle were immunised against Corridor disease (Theileria parva lawrencei infection) on a farm with a history of heavy and often lethal theilerial challenge. Nineteen cattle were immunised by treating with two doses of long-acting oxytetracyclines given at 20 mg/kg on days 0 and 4 after sporozoite stabilate inoculation, while the other 18 were treated with naphthoquinone buparvaquone, given as a single dose of 2.5 mg/kg simultaneously with stabilate inoculation. All the cattle underwent subclinical theilerial reactions with all but two developing high antibody titres on the IFAT test against T. parva schizont antigen by day 35 after the immunisation. Both buparvaquone and long-acting oxytetracycline appeared equally effective in the immunisation. To date, 26 months later, only two cases of theileriosis parasitologically characteristic of T. p. parva have been reported in the immunised cattle. Following the two cases, investigations showed that when uninfected Rhipicephalus appendiculatus nymphal ticks were deliberately fed on healthy resident cattle on the farm, the resultant adult ticks transmitted acute and lethal theilerial infections to five out of five susceptible cattle. The resultant infections were parasitologically characteristic of T. p. parva infections. Furthermore, the monoclonal antibody profiles of schizont infected cell lines from these infections appeared to be characteristic of T. p. parva. It was thus concluded that resident cattle on the farm could be a potential source of T.p. parva infection which had broken through the immunity of T.p. lawrencei immunised cattle and could constitute a reservoir of theilerial infection for ticks and hence to susceptible stock on the farm.     

Further evaluation of the use of buparvaquone in the infection and treatment method of immunizing cattle against Theileria parva derived from African buffalo (Syncerus caffer).

Three experiments were undertaken to determine the efficacy of different doses of buparvaquone in the infection and treatment immunization of cattle against Theileria parva derived from African buffalo (Syncerus caffer). Two of these experiments also compared buparvaquone with standard doses of long- and short-acting formulations of oxytetracycline. In addition, different dilutions of stabilates were used in the experiments. In the first experiment, a 10(-1.0) dilution of stabilate was used to infect groups of cattle treated with buparvaquone at doses of between 5 and 0.625 mg kg-1 body weight (bwt) on Day 0 after infection. All control cattle developed severe theileriosis and none of the treatment regimes (including those utilizing long-acting oxytetracycline) prevented the development of theileriosis. Treatment with buparvaquone at 2.5 mg kg-1 bwt or oxytetracycline gave the most satisfactory results. In the second experiment when the sporozoite dose was reduced to 10(-2.0) dilution, buparvaquone treatment at 5 and 2.5 mg kg-1 bwt and short- and long-acting formulations of oxytetracycline reduced reactions greatly. While all the oxytetracycline treated animals produced a serological response and were immune to a 50-fold higher challenge with the immunizing stabilate, several animals in the buparvaquone groups did not show a serological response and were not immune to challenge. In the third experiment, groups of cattle were infected with 10(-1.2), 10(-1.4) and 10(-1.6) dilutions of stabilate and were treated with 2.5 mg kg-1 bwt of buparvaquone. No animals developed severe theileriosis and all seroconverted. On homologous challenge, however, two out of 14 cattle showed severe reactions. It was concluded that further work on immunization using buparvaquone treatment at 2.5 mg kg-1 bwt and 10(-1.6) dilution of the stabilate would have to be carried out before such a system could be used in the field.     

A review of tree fodder production and utilization within smallholder agroforestry systems in Kenya

Although the biological advantages in terms of animal production and improved soil fertility of the use of herbaceous legumes have been well demonstrated in Kenya and elsewhere, adoption by small-scale farmers has often been disappointing. This has led to increased research into the use of both indigenous and exotic fodder trees. In common with conventional pasture legumes, tree fodders contain high levels of crude protein and minerals and many show high levels of digestibility. They are readily accepted by livestock and presumably because of their deep-root systems, they continue to produce well into the dry season. Antinutritive factors can be a problem, however, and polyphenolics, toxic amino acids, cyanogenic glycosides and alkaloids are found in many tree species. There are abundant niches on small farms where fodder trees can be grown without affecting crop production. Although detailed management recommendations are lacking, guidelines exist with regard to appropriate cutting heights and harvesting frequencies. In the Embu region, it has been estimated that three kg of fresh fodder of Calliandra calothyrsus has the same effect on milk production as one kg of commercial dairy meal. Up to about 500 trees (250 m of hedgerow) will produce enough fodder to supplement one dairy cow for a complete lactation. The tree fodder can either replace the concentrate without loss of yield, or it can complement it to produce more milk. It is being enthusiastically adopted by small-scale farmers, many of whom are starting to produce their own seed. Other tree species are now being studied in order to avoid over-reliance on a single fodder species. This revised version was published online in August 2006 with corrections to the Cover Date.     

Comparison of indirect fluorescent antibody test and enzyme linked immunosorbent assay in the detection of exposure of cattle to Theileria parva in Kenya.

Appraisal of the indirect fluorescent antibody test (IFAT) and antigen enzyme linked immunosorbent assay (ELISA) serological tests as carried out to detect cattle exposed to Theileria parva at the National Veterinary Research Centre, Muguga (NVRC), Kenya is reported. Using sera from T. parva naive cattle and cattle experimentally exposed to T. parva, the two tests were appraised in terms of their sensitivity and specificity. IFAT and ELISA had the same sensitivity of 90% while ELISA had a higher specificity (90%) than IFAT (80%). A comparison was also made of the capability of the two tests to detect exposure of dairy cattle to T. parva prior to immunization against East Coast fever (ECF). The positive outcome from the IFAT was significantly higher (chi 2 = 30.36; P < 0.001) than that from the ELISA. The agreement between the two tests was low (Kappa = 0.21). The two tests indicated a higher risk of ECF in the study area than was expected. Indications are that the ELISA has been effectively adopted at NVRC.     

Modelling the impacts of various thinning intensities on tree growth and survival in a mixed species eucalypt forest in central Gippsland,Victoria, Australia

The response of tree survival and diameter growth to thinning treatments was examined over 29 years, in various thinning treatments established in a 21-year-old even-aged mixed species regenerating forest in Victoria, Australia. The treatments were control, crown release, strip thinning and three different intensities of thinning from below (light, moderate, and heavy). Each treatment was replicated three times in a complete randomised design. Logistic and multilevel regression analyses showed that tree survival, growth and thinning response (change of tree growth due to a thinning treatment) were functions of tree species, size, age, removed and remaining competition, as well as time since the treatment. Mean annual tree diameter growth in unthinned stands was highest for Eucalyptus sieberi L. Johnson (1.9 mm) followed by Eucalyptus baxteri (Benth.) Maiden & Blakely ex J. Black (1.6 mm), and lowest for both Eucalyptus consideniana (Maiden) and Eucalyptus radiata (Sieber ex DC) combined (0.7 mm). Diameter growth increased with tree size for both E. sieberi and E. baxteri, but not for E. consideniana and E. radiata. Smaller trees were more likely to die due to shading and suppression than their larger counterparts. A mortality model suggested, however, that both shading and suppression had very little effect on trees in both E. consideniana and E. radiata species, which were less likely to die compared to trees in the other species. This result indicates that both E. consideniana and E. radiata species may be relatively shade tolerant compared with the other species. Total thinning response was a sum of positive (increased growing space) and negative (thinning stress) effects. Following thinning, smaller trees showed signs of thinning stress for the first one or two years, after which the highest percentage thinning response was observed. While larger trees were initially less responsive to thinning, the rate of decrease in the response for subsequent years was greater in smaller trees than larger ones. The average amount of thinning response showed similar trends to diameter growth increasing from E. sieberi (1.7 mm) through E. baxteri (0.6 mm) to both E. consideniana and E. radiata (0.5 mm). This translates into low average percentage thinning response in E. baxteri (34%), twice as much in both E. consideniana and E. radiata (69%) and highest overall percentage response in E. sieberi (87%). Thinning response and the duration of this response appeared to increase with thinning intensity and was still evident 29 years after thinning. Heavy thinning did, however, reduce the number of trees to a severely under-stocked condition, which prohibited optimum site occupancy, requiring 29 years of post-thinning development for the heavily thinned stands to regain their pre-thinning stand basal area.