Determination of the persistence of tetracycline antibiotics and their degradates in manure-amended soil using enzyme-linked immunosorbent assay and liquid chromatography-mass spectrometry

The persistence of manure-borne oxytetracycline in soil was investigated under field conditions. Soil cores were collected approximately once a month for over a period of two years and subsampled at depth increments of 0-5, 5-10, 10-15, 15-36, and 36-71 cm. Soil samples were analyzed by enzyme-linked immunosorbent assay (ELISA) and/or by liquid chromatography-mass spectrometry (LC-MS). Whereas LC-MS showed that oxytetracycline declined to <50% of its initial soil concentration after 3 weeks, ELISA showed that the total tetracyclines did not decline significantly 5 months after manure application. The differences between ELISA and LC-MS results are attributed to the broad cross-reactivity of the antibodies employed, which detect many structurally related tetracyclines, including their isomers and degradation products. Only trace amounts (< or = 1.0 microg/kg) of oxytetracycline were observed in the subsurface soil, and none was detected in water samples from field lysimeters, suggesting that oxytetracycline has low mobility in soil.     

Intraparticle diffusion process occurring during adsorption of dyestuffs

The adsorption of a dyestuff, Telon Blue (Acid Blue 25) on Fuller's earth and Astrazone Blue onto fired clay has been studied. An intraparticle diffusion rate parameter has been defined characteristic of the rate of diffusion after the early stages of the adsorption. The rate parameter has been determined for a number of variables including adsorbent mass, initial dye concentration, and particle size.     

Simultaneous analysis of free and conjugated estrogens, sulfonamides, and tetracyclines in runoff water and soils using solid-phase extraction and liquid chromatography-tandem mass spectrometry

The ability to monitor multiple analytes from various classes of compounds in a single analysis can increase throughput and reduce cost when compared to traditional methods of analyses. This method for analyzing free (parent estrogen) and conjugated estrogens (metabolites) along with sulfonamides and tetracyclines utilizes a high pH (10.4) mobile phase with an ammonium hydroxide buffer for both positive- and negative-mode electrospray ionization. A single-step sample preparation by solid-phase extraction (SPE) was used to isolate and concentrate all analytes simultaneously. The analytical method was developed and validated for recoveries at 3 concentration levels for water and soil and produced recoveries of 42-123% and 21-105% respectively. Method detection limits ranged from 0.3 to 1.0 ng/L for water samples and 0.01 to 0.1 ng/g for soils. The method quantification limit ranged from 0.9 to 3.3 ng/L for water samples and 0.06 to 0.7 ng/g for soils. The single-point standard addition calibration procedure was validated across a linear range of MQL to 100 ng/L with ≥82% accuracy against a matrix matched standard curve. Furthermore, sorption of tetracyclines onto glassware was investigated and minimized by 10% using nitric acid-rinsed glassware, while separation parameters were further optimized based on retention time and signal responses. This method has been used for the quantification of estrogens, tetracyclines, and sulfonamides in soil and runoff waters with multiple compounds detected simultaneously in a single analysis.     

Evaluation of Compost Activators for Composting Grass Clippings

The effects of seven manufactured commercially available activators were evaluated for their efficiency in the composting of yard trimmings (grass clippings/wood chip mixture). Two naturally available additives, and a control (absence of activator) were also evaluated. Four measures of composting efficiency were used to compare the overall decomposition response for each activator: weight loss, volume reduction, volatile solids decrease, and oxygen uptake rate. Four experimental blocks were set up in the field, and two experimental blocks were set up in the laboratory. The physical/chemical characteristics of the compost material were monitored as a function of time for each additive. Interrelationships between measures of composting efficiency were also evaluated. Results showed that grass clippings can be composted as efficiently with naturally available materials such as topsoil or mature compost, as with commercially available compost activators, or an unactivated control. The cost of commercially available activators was $1.37 to $9.36 per cubic yard of compostable grass clippings. Naturally available materials such as topsoil and mature compost are available in needed quantities at no cost to backyard composters.     

Investigation of Marek’s disease virus from chickens in central Ethiopia

Marek’s disease (MD) is a lymphoproliferative and neuropathic disease of domestic chickens and less commonly, turkeys and quails, caused by a highly contagious, cell-associated, oncogenic herpesvirus. In Ethiopia, MD is believed to be introduced with importation of exotic and crossbred to improve the poultry production and has been reported to be a potential threat to the poultry sector both in backyard and commercial farming systems. This study was aimed at isolation and molecular analysis of MD virus isolates circulating in chicken population in the central part of Ethiopia where commercial farms are populated. From September 2013 to January 2014, clinical and post-mortem examination were conducted on diseased chickens suspected of MD virus infection. Representative spleen and feather follicle samples were collected following sterile procedure, and infectious virus isolation was performed using primary chicken fibroblast cell culture. Cell culture inoculated with suspension of pathological samples developed characteristic MD virus cytopathic effect of rounding of the cells and small plaques. Further analysis of the virus was conducted by conventional PCR amplifying the ICP4 gene fragment from eleven tissue samples using MD virus specific primers. PCR products were further sequenced and analyzed. Nucleotide sequence similarity search of the local isolates resulted a high degree of sequence similarity with Gallid Herpes virus type 2 strain (Marek’s disease virus type 1, JN034558). To our knowledge, the present study is the first report conducted on virus isolation and molecular characterization of MD virus isolates circulated in Ethiopia. Eleven ICP4-like gene fragment (318 bp) sequences generated in the present study were uploaded in the public database (KU842366–76). Further research on virus isolation, genetic characterization, and infection dynamics is recommended targeting chickens of all age groups reared in different agro-ecological zones under different production system.

     

Serological survey of African horse sickness in selected districts of Jimma zone,Southwestern Ethiopia

A cross-sectional serological survey was undertaken in selected districts of different agro-ecology of Jimma zone (Dedo, Yebu, Seka, Serbo, and Jimma town) from November 2009 to February 2010 to determine the seroprevalence of African horse sickness virus and associated risk factors of the disease. Two hundred seventy-four equids (189 horses, 43 mules, and 47 donkeys) with a history of non-vaccination for at least 2 years were selected randomly from the above areas. Sera samples were collected and assayed for the presence of specific antibody against African horse sickness virus using blocking ELISA. An overall seroprevalence of 89 (32.5%) was found and it was 24 (51.1%) for donkeys, 13 (30.2%) for mules, and 52(28.3%) for horses. Seroprevalence was significantly (X ² = 11.05, P < 0.05) different among the different species of equids. Seroprevalence was also significantly (X ² = 11.43, P < 0.05) different among the different agro-ecological areas being higher in highlands 47 (40.5%) followed by midland 30 (34.5%) and lowland 12 (16.9%). Age and sex were not significantly (X ² = 3.15, P > 0.05 and X ² = 3.38, P > 0.05, respectively) associated with seroprevalence of AHSV. The present study showed that African horse sickness (AHS) is highly prevalent disease for the horses followed by mules and then donkeys in Jimma zone explained by lower seroconversion rate. Therefore, control strategy against AHS should target at high risk species of all age and sex in their locality in the initial stage for better containment of the disease.     

Study on small ruminant lungworms in northeastern Ethiopia

A cross-sectional study of lungworm infection was carried out with the aim of determining the prevalence of lungworm infection of small ruminants and identifying the species of the respiratory helminthes circulating in six districts of northeastern Ethiopia: Debresina, Legambo, Habru, Kalu, Chaffa-Dawi and Artumana-Fersejelle. Faecal and postmortem examination were conducted from 1162 and 104 animals, respectively. An overall infection rate of 53.6% and 66.3% was found by faecal and postmortem examinations, respectively. Significant difference (p<0.05) was found between areas of different altitude with an infection rate of 30.4%, 32.5% and 71.3% at low, medium and high altitude areas, respectively. Prevalence on the different months was insignificant (p>0.05). The prevalence of Dictyocaulus filaria and Muellerius capillaris infection showed a significant difference (p<0.05) between young, adult and old age groups. The prevalence of D. filaria decreases and that of M. capillaris increase with increasing age of the animal. Animals under relatively good management system have been found less affected with significant difference (p>0.05) than their counterparts at relatively poor management system. The infection rate between male and female animals showed significant difference (p<0.05) with prevalence rate of 44.4% and 59.3%, respectively. A significant difference between sheep and goats was also noted with infection rate of 24.4% and 50.7%, respectively. Monthly worm burden of D. filaria infection showed significant difference (p>0.05) while it was insignificant in case of M. capillaris. Due to its impact on production, emphasis should be given for the control and prevention of lungworm infection in highland areas.     

Farmers' knowledge,perceptions, and management practices of the new invasive pest,fall armyworm (Spodoptera frugiperda) in Ethiopia and Kenya

This paper reports for the first time on farmers’ knowledge, perceptions and management practices of the fall armyworm (Spodoptera frugiperda) in Ethiopia and Kenya. A survey of 343 smallholder maize farmers was conducted. Most farmers in Ethiopia and Kenya had knowledge about fall armyworm; they could identify it mainly during its larval stage. Furthermore, most farmers in Ethiopia (93%) and Kenya (97%) encountered damage by fall armyworm in their farms. They estimated an average of 32% crop damage in Ethiopia and 47.3% of crop damage in Kenya, with an estimated yield reduction between 0.8 to 1 tonnes/ha. Nearly half of the farmers relied on chemical insecticides to control this pest. The majority (60%) of the farmers in Kenya perceived that insecticides were not effective in controlling fall armyworm as compared to most farmers (46%) in Ethiopia who perceived that chemical spray is effective for the control of fall armyworm. In Ethiopia, 26% of the farmers combined handpicking larvae with insecticide sprays, whilst 15% of the farmers practiced only handpicking. The present study highlights the need to develop management strategies for fall armyworm based on farmers’ needs and priorities.     

Inverse Sequence-tagged Repeat (ISTR) Analysis of Genetic Variability in Forest Coffee (Coffea arabica L.) from Ethiopia

Genetic diversity in forest coffee (Coffea arabica L.) was estimated using inverse sequence-tagged repeat (ISTR) markers. One hundred ninety two samples representing 16 populations of C. arabica from four regions of Ethiopia were analyzed with 12 pairs of forward and backward ISTR primer combinations. A total of 144 reproducible bands were generated out of which 37 (25%) were polymorphic and scored as present (1) or absent (0) data matrix. This data was used to compute Jaccard coefficient to estimate genetic variability among all possible pairs of samples. The proportion of polymorphic bands within populations ranged from 19% for Bale-3, to 54% for Walega-2 populations. Un-weighted pair group method with arithmetic mean (UPGMA) based cluster analysis generated two clusters at 56% similarity value. The samples were clustered on the basis of their geographical origin, which could be attributed to a few region specific banding patterns detected. However, within regions most of the samples failed to cluster on the basis of their respective populations, which may be due to the presence of substantial gene flow between local populations in the form of seedlings carried out by farmers. The results may provide information to develop strategies for in situ conservation.