Sensitive diagnosis of bovine tuberculosis in a farmed cervid herd with use of an MPB70 protein fluorescence polarization assay

After histopathological examination of a lesion found in a herd member returned a diagnosis of mycobacteriosis, a farmed herd (n = 47) of elk (Cervus elaphus nelsoni) and red deer (C. elaphus elaphus) was investigated for bovine tuberculosis with a battery of antemortem and postmortem diagnostic tests. Every animal was tested with the mid-cervical tuberculin skin test; all 47 had negative results. All of the 16 adult animals and 15 of the 31 calves (approximately 2-years-old) were blood-tested with a lymphocyte stimulation test (LST) and a fluorescence polarization assay (FPA), which detects antibody to the MPB70 protein antigen. At necropsy of the 31 blood-tested animals, tissues were harvested for histopathological examination and culture of mycobacteria. Mycobacterium bovis was isolated from 16 of the 31 animals, and a scotochromogen was also isolated from 1 of the 16 whose tissues yielded M. bovis. Each of these 16 animals, 15 of which were calves, also received a histopathological diagnosis of mycobacteriosis. Other species of mycobacteria, including those belonging to the M. avium and M. terrae complexes, were isolated from an additional 7 animals. The FPA was scored “positive” or “suspect” for 16 animals, 13 (81%) of which were culture-positive for M. bovis. The other 3 animals that were culture-positive for M. bovis had negative FPA results. Of the 3 FPA-positive or FPA-suspect animals that were culture-negative, 2 were suspected to have mycobacteriosis on the basis of the histopathological examination. The 7 animals from which Mycobacterium species other than M. bovis were cultured were all FPA-negative. The only animal with positive LST results was also FPA-positive and culture-positive for M. bovis. The M. bovis isolates had an identical spoligotype pattern, with an octal code of 664073777777600. This is the first report of the isolation and identification of this strain type in Canada.     

Impact of a natural bluetongue serotype 8 infection on semen quality of Belgian rams in 2007

In 2006, bluetongue (BT) virus serotype 8 emerged in northern Europe and numerous ruminants were affected in the following year. Infertility in males is one of the consequences of BT, although its severity and duration after natural infection has not been documented. In this report, the impact of BT-8 on clinical signs and semen quality of naturally infected rams is described through a longitudinal study of two Belgian ram populations (n = 12 and n = 24) and a cross sectional study in a further ram population (n = 43).Macroscopic semen characteristics, semen concentration, motility, percentage of living and dead spermatozoa were assessed in 167 semen samples collected on 1–6 occasions from 79 BT-8 infected rams within 5–138 days after onset of clinical disease. These were compared with healthy control animals. Significant changes in all variables were observed after natural BT-8 infection. Total recovery occurred around 85 days after clinical disease in animals undergoing a close follow-up of semen quality. Good correspondence between the results of the longitudinal and cross sectional studies suggests that semen quality of BT-8 affected rams reached normal references values 63–138 days after clinical diagnosis of BT. In addition, semen concentration seems to be a sound epidemiological indicator of ram semen quality.     

Estimates of Bottom Soil and Effluent Load of Phosphorus at a Semi-intensive Marine Shrimp Farm

A phosphorus budget for a single crop was prepared for a 685‐ha semi‐intensive shrimp farm that consistently has produced about 3000 tonnes/yr of black tiger prawn, Penaeus monodon. Phosphorus inputs were shrimp stock, 0.31 kg/ha; triple superphosphate, 1.38 kg/ha; incoming water, 25.8 kg/ha; and feed, 65.3 kg/ha. Phosphorus outputs were harvested shrimp, 5.43 kg/ha, and outflow for water exchange and draining, 42.7 kg/ha. The high clay‐content soil in pond bottoms adsorbed 45.2 kg/ha of phosphorus. Water was taken from and released back into the same estuary and bay. The phosphorus contribution of shrimp farming to the receiving water body was the difference between the amount of phosphorus in effluent and that in the incoming water, which was 16.9 kg/ha. Bottom soil accumulated 67.8% of phosphorus added to the ponds. Another estimate of soil phosphorus uptake based on the relationship between cumulative phosphorus applied to ponds as fertilizer and feed and soil phosphorus concentration suggested that 63.2% of fertilizer and feed phosphorus had accumulated in pond bottoms. The farm effluent phosphorus load was 23.5 tonnes/yr. The estuary and bay system has an estimated volume of 4.8 × 10⁹ m³, and the annual phosphorus input from the farm had a concentration equivalent of 0.005 mg/L, and there were no other major inputs of phosphorus. The estuary and bay are flushed by freshwater inflow and tidal action, and the farm input is not likely to cause eutrophication.     

Physical and chemical characteristics of soil from tiger shrimp aquaculture ponds at Malacca,Malaysia

Soil physicochemical properties of the growout ponds of black tiger shrimp (Penaeus monodon) were examined in relation to shrimp yields for one production cycle. The culture ponds were old (>5 years) and new (newly constructed) types. Soil texture was silty clay with low sand content and high proportion of clay for both the pond types with alkaline soil pH (7.87–9.71). Organic matter (OM) concentration was higher (7.48 ± 0.01%) in old ponds and positively related (r = 0.58, P < 0.05) with total nitrogen (TN). The major cations (Ca, Mg, and Na) were higher in the soil of old ponds and did not fluctuate significantly during culture. The majority of trace elements, i.e., Fe (349.22 ± 35.7 ppm), Mn (56.19 ± 30.2 ppm), Zn (88.56 ± 8.09 ppm), Al (454.3 ± 200.6), Pb (1.3 ± 0.96 ppm), Co (3.4 ± 0.2), V (6.56 ± 1.79 ppm), Cr (19.32 ± 0.63 ppm), Ti (82.78 ± 54.3 ppm), As (5.60 ± 0.28 ppm), Ag (0.38 ± 0.5 ppm), and Sb (3.89 ± 0.48 ppm) were found to be higher in new pond soils than the old ponds. Except for soil manganese, no major fluctuations in trace elements were observed during the culture period. Shrimp growth was not significantly different in the two types of ponds, and no distinct correlation between shrimp growth and element content of soils could be drawn. The results indicate that shrimp pond age may not affect production of shrimp if soils are properly managed pre- and postculture. The differences in production in different ponds might be the result of management practice such as quality of shrimp post larvae, pond preparation, water and feed quality, and available live feed in the pond bottom or other environmental factors like water nutrients and physicochemical parameters.     

Larval rearing of African carp,Labeo parvus Boulenger, 1902 (Pisces: Cyprinidae), using live food and artificial diet under controlled conditions

This study aimed at (1) evaluating the efficacy of live food organisms (Artemia and natural zooplankton) and an artificial diet in the larval rearing of African carp Labeo parvus and (2) determining appropriate rearing conditions. After yolk sac resorption, the larvae were separated into five different feeding trials with two replicates. At the end of the larval rearing period (28 days post‐hatching), the highest (94.6%) and the lowest (53.7%) cumulative survival rates were found when larvae were fed with natural zooplankton for 7 days followed by Nippai food for 21 days, and when larvae were fed from the beginning of exogenous feeding with Nippai food only respectively. The significant highest body weight (351.6 mg), total length (34.4 mm) and specific growth rates (15.5%day^?1) were recorded when the larvae were fed with Artemia nauplii for 14 days followed by Nippai food for 14 days. The lowest growth performance (body weight and specific growth rates) were obtained when larvae were fed exclusively Nippai food. These results indicate that L. parvus can be successfully cultured in indoor nursery systems from hatching to the early juvenile stage.     

Characterization of Pterocarpus macrocarpus (pradoo wood) biochar and its effect on the retention properties of sandy soils in Northeast Thailand

Pradoo wood biochar has been tested in order to explore sustainable solutions to the development of agriculture on poor sandy soils in marginal areas in Northeast Thailand. Some basic physicochemical properties of biochar, for example pore size distribution, cation exchange capacity (CEC), specific surface area (SSA), and water and nutrient adsorption, were determined and compared to soil properties in order to determine appropriate biochar application to soil. Pradoo wood biochar showed important adsorption properties with high SSA, CEC and nutrient adsorption. The water retention properties were also improved on the dry end of the water retention curve. Phosphorous and ammonium adsorption–desorption isotherms were established and their respective affinity for the biochar surface was quantified, by the means of a retention index and thermodynamical parameters. We found that despite excellent retention properties, biochar needs to be added in large amounts (between 10 and 70 kg m⁻²) to soil to be able to modify noticeably the resulting soil properties.