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1.
An iron-sulfur compound (Fe3S2) was synthesized at pressures greater than 14 gigapascals in the system Fe-FeS. The formation of Fe3S2 changed the melting relations from a simple binary eutectic system to a binary system with an intermediate compound that melted incongruently. The eutectic temperature in the system at 14 gigapascals was about 400°C lower than that extrapolated from Usselman's data, implying that previous thermal models of Fe-rich planetary cores could overestimate core temperature. If it is found in a meteorite, the Fe3S2 phase could also be used to infer the minimum size of a parent body. 相似文献
2.
F. G. Irungu C. M. Mutungi A. K. Faraj H. Affognon C. Tanga S. Ekesi D. Nakimbugwe K. K. M. Fiaboe 《International Aquatic Research》2018,10(2):101-113
Animal food sources provide human beings with minerals considerably in adequate quantities. Fish is an indispensable reliable source of nutrients, as aquaculture is a sector that is fast growing and which provides 50% of the world’s fish production. However, fish production is hampered by the increasing costs of feeds due to the ever rising cost of fish meal, an integral component of fish feeds. Substituting fish meal with cheap, yet highly nutritious ingredients in fish feeds is therefore paramount. This study investigated the effects of substituting fish meal with adult cricket meal (ACM) and black soldier fly meal (BSFM) on minerals content of extruded fish feeds, where four levels of substitution (0, 25, 50 and 75%) were used. The effect of feed moisture content on minerals was also studied where 20 and 30% feed moisture levels were used. Leaching effects of the pellets were studied as well. The results showed a significant increase (P < 0.05) in the levels of phosphorus and potassium as the level of fish meal substitution increased from 0 to 75%. On the other hand, iron and sodium levels reduced significantly (P < 0.05) as the level of fish meal substitution increased. Magnesium content increased with increasing level of substitution with BSFM, but decreased with increasing level of substitution with ACM. Copper, zinc and manganese were not greatly influenced by levels of fish meal substitution. Diets that had zero substitution showed higher leaching effect for most minerals than diets that were substituted with 75% ACM or BSFM. This study found that both ACM and BSFM can be used to substitute fish meal in fish feeds and obtain adequate mineral profile and low leaching effect. 相似文献
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A study to compare the profitability of rearing sheep and goats under natural trypanosomosis challenge was carried out on Galana ranch in south-eastern Kenya between July 1996 and October 1997. Seventy-nine male weaner sheep and 79 male weaner goats were monitored monthly for weight changes and fortnightly for trypanosomosis. The animals of each species were divided into two groups. Group 1 was an untreated control, while group 2 was treated with isometamidium chloride (Samorin) at 0.5 mg/kg body weight every 3 months. In both groups, trypanosome infections were detected by microscopy and treated with diminazene aceturate (Veriben), at 3.5 mg/kg body weight, when the packed cell volume reached 17% or below. The profitability of each drug regime was expressed as the marginal revenue over the cost of trypanosomosis (MOT). There were greater losses occasioned by trypanosomosis in sheep than in goats. Animals of both species on chemoprophylaxis gave higher MOT values than those that received chemotherapy on diagnosis. However, the MOT values for the chemoprophylactic regime were higher for sheep than for goats, suggesting that the greater weight gain by sheep more then compensated for the higher cost of maintaining them under high trypanosomosis challenge. Thus, a Galana rancher would be better off keeping sheep rather than goats, other things being equal. The marginal revenue per dose of Samorin was lower than that of Veriben for both species, suggesting that strategic use of Samorin timed to precede the peak incidence of trypanosomosis might be a better option to raise the overall profitability in sheep and goats. 相似文献
4.
Masiga DK Okech G Irungu P Ouma J Wekesa S Ouma B Guya SO Ndung'u JM 《Tropical animal health and production》2002,34(6):489-501
Trypanosomosis is a major impediment to livestock production and economic development in those areas of Africa where it is endemic. Although small ruminants appear to perform better than cattle in various agro-ecological zones, the importance of trypanosomosis has not been extensively investigated in these livestock. This study was designed to investigate the prevalence of trypanosomosis in sheep and goats in an endemic area and to evaluate the performance of different breeds under high tsetse challenge and the potential role of chemoprophylaxis in the control of the disease. The results showed that tsetse flies feed readily on small ruminants, and that these animals are susceptible to trypanosomosis. The Small East African goats acquired fewer infections than the Black Head Persian and Dorper sheep used in the study. In both sheep and goats, chemoprophylaxis with isometamidium chloride (Samorin, Rhone Merieux, Annecy, France) was protective, resulting in fewer infections and higher body weight gain. Trypanosomosis caused anaemia in both sheep and goats, and animals whose PCV fell below 15% rarely recovered, even with trypanocidal drug treatment. The peak transmission period was between 1 and 3 months after the peak tsetse fly density, which raises the possibility of effective strategic prophylaxis. 相似文献
5.
Four thousand nine hundred and seventy-one trypanosomosis-surveillance records from an open population of Orma Boran cattle raised under natural trypanosomosis challenge in Galana Ranch, Kenya between the years 1990 and 2000 were analysed. The objective of the analysis was to identify epidemiological factors that influenced time-to-treatment of trypanosomosis cases. Under the surveillance programme, blood was being examined fortnightly for trypanosomosis using buffy coat technique. Infected animals were treated when their packed cell volumes (PCV) fell to 25% or lower. The number of days between the first diagnosis and treatment of trypanosomosis cases was obtained from the difference between diagnosis and treatment dates. Days-to-treatment clustered around the screening periods; therefore, time-to-treatment was represented by a series of time points 0-8 at 14-day intervals. Factors postulated to affect the outcome (time-to-treatment) were age of an animal at time of diagnosis, sex, number of trypanosome infections, trypanosome species and season of the year. Five animal generations were generated from birth dates and treated as nuisance parameters. Conditional logistic regression and Cox proportional hazards models were fitted to the data, the former to analyse factors that influenced treatment after time 0 (outcome dichotomised as time 0 or >0) and the latter to analyse factors that influenced time-to-treatment for cases that were treated after time 0, excluding all cases treated on time 0. The majority of the cases (89.5%) were treated on the same day of diagnosis. Trypanosome infections were more likely to be treated after time 0 in dry than in wet season. Similarly, the rate of treatment was lower in the dry than the wet season. An increase in number of previous trypanosome infections reduced the odds of an animal being treated after time 0. Animals that had been exposed to many infections before had higher rates of treatment than those that had minimal experiences. We offer possible reasons for these observations and conclude that selection of animals for breeding purposes in programmes geared towards improving trypanotolerance should take into consideration the environmental factors that affect classification of an animal as being resistant or susceptible. 相似文献
6.
A study was carried out on 456 indigenous poultry intestinal specimens from various towns in Kenya to determine the occurrence and distribution of helminth parasites in the intestinal tract of the birds. Of the specimens examined, 414 had parasites whereas the remaining 42 had none, which is an infection rate of 90.78%. The main species of helminths found in the intestines were Raillietina sp. (47.53%), Heterakis gallinarum (21.33%), Ascaridia galli (10.03%), Strongyloides avium (9.96%), Choanotaenia infundibulum (4.61%), Cotugnia digonopora (3.6%), Capillaria sp. (1.5%), Trichostrongylus tenius (1.04%) and Syngamus trachea (0.40%). Most helminths were present in both the mid- and hindguts. Syngamus trachea and C. digonopora were only found in the foregut and midgut, respectively. Although chickens from which the specimens were collected appeard healthy, the high prevalence of helminthiasis observed shows the poor level of helminth infection control practiced by the indigenous poultry keepers in the country, which might affect the health status of the birds and their growth rates. Poultry keepers should be encouraged to prevent, control and treat such cases. 相似文献
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8.
Recent syntheses of high-pressure alkali and alkaline earth silicates reveal a class of framework structures with corner-linked 4- and 6-coordinated silicon. These compounds possess the structural formula (A4-2x1+Bx2+)SimVI(SinIVO2(m+n)+2), where x, m, and n specify the amounts of alkaline earth, 6-coordinated silicon, and 4-coordinated silicon, respectively. Appropriate values of m and n yield a range of high-pressure structures, from fully 4-coordinated to fully 6-coordinated silicate frameworks. Recognition of this class of framework silicates leads to predictions of high-pressure structures as well as room-pressure isomorphs of high-pressure silicates. 相似文献
9.
Paul Nyang’au Rose Marubu John Bwire Nixon Onyimbo Janet Irungu 《Journal of Sustainable Forestry》2020,39(6):543-562
ABSTRACT Forest conservation by peripheral communities is one of the most advocated strategies for ensuring sustainable supply of forest goods and services. In Kenya, although conservation activities generate considerable environmental improvements, studies evaluating the economic benefits are very limited. This study aimed at assessing the impact of participating in the commercialization training program by forest adjacent communities on farm income. Utilizing matching techniques, the analysis is based on the data collected from a randomly selected sample of farm households around Kakamega forest in Kenya. The results show that age, forest distance, forest benefit, market distance, and farming experience are the main factors that influence the participation in the commercialization program. Also, participating in commercial production of medicinal plants has a positive and significant effect on farmers’ income. The average treatment effect on the treated (ATT), based on three estimation algorithms, ranges from KSH. 80,047 to KSH. 176,788 per hectare, per year, implying that policy efforts that focus on the participation in the commercialization program of medicinal plants can enhance incomes among farm-dependent households. The findings from this study suggest that upscaling the participation in the commercialization program to other areas. 相似文献
10.
Performance of Community-based Animal Health Workers in the Delivery of Livestock Health Services 总被引：1，自引：1，他引：0
Since the liberalization of animal health services in Kenya in the early 1990s, community-based animal health workers (CBAHWs) have become an important alternative animal health delivery channel in the country's marginal areas. However, professional veterinary practitioners have questioned the effectiveness of CBAHW programmes in animal health service delivery in Kenya. This is partly due to lack of information about their performance and partly because CBAHW programmes were implemented before the necessary changes in the existing legal, policy and institutional frameworks had been made. This study was designed to provide such information. In this regard, the productivity of livestock herds among farmers who utilized the services of CBAHWs was compared to that of livestock belonging to farmers who utilized the services of professional veterinarians. The annual live births per mature female (birth ratio) and the proportion of young stock to mature females (breeding index) was computed over a period of 3 years in cattle and goat herds under care of CBAHWs and professional veterinarians. The birth ratios in cattle and goats under CBAHWs were not significantly different from those under the care of professional veterinarians (p > 0.05). Furthermore, the breeding index of cattle and goats under the two categories was not statistically different. Besides the CBAHWs providing clinical services, they also created positive externalities through participatory learning enjoyed by neighbouring livestock keepers, who later dispensed with their services. Policy attention is therefore needed to enhance the participation of CBAHWs in animal health service delivery and to appropriately integrate their activities into the existing formal animal health delivery system in Kenya. Interventions that improve the professional development of these workers, with emphasis on areas pertaining to care of young stock, would not only promote the sustainability of CBAHW programmes but would also improve livestock productivity in the country's marginal areas. 相似文献