Soil chemical and biochemical properties of a salt-marsh alluvial Spanish area after long-term reclamation

Marisma, one of the largest salt-marsh alluvial areas in SW Spain, has been reclaimed since 1970 by artificial drainage and amendment with phosphogypsum (PG) so as to reduce Na⁺ saturation. Within the reclaimed area, two 250- × 20-m plots were treated as follows: (1) amendment with 25 Mg/ha of PG every 2 to 3 years between 1979 and 2003 (plot PY); (2) like PY but PG treatment stopped after 1997 (plot DR). A contiguous virgin Marisma salt-marsh plot (MV), neither drained nor amended, was the control. In MV, soil microbial biomass C, most enzyme activities and total organic C content were much greater than in PY and DR soils, despite the salinity stress. The decrease in soil organic matter content in PY and DR soils was likely due to cotton-cropping practices, which favoured the organic C mineralisation and nutrients removal by crops. Microbial activity of MV soil, probably stimulated by the rhizodepositions of the natural vegetation, did not suffer from the osmotic effect due to the raising of soil solution ionic strength. Microbial quotient could be ranked as MV > PY > DR, whereas the metabolic quotient had an opposite trend. Thus, both quotients suggested that the interruption of PG amendment was not favouring microbial activity. Principal component analysis clearly identified the chemical and biochemical soil properties mostly affected by the reclamation and also indicated the longer PG amendment in PY plot. Stepwise discriminant analysis identified two physiologically different types of soil microflora, one less active present in the MV virgin soil and another more active present in the reclaimed PY and DR soils.     

Effect of dietary protein:energy ratio on intake, growth and metabolism of juvenile green abalone Haliotis fulgens

Juvenile green abalone Haliotis rufescens were grown under laboratory conditions at 21±1 °C and fed formulated diets consisting of different protein:energy ratios (mg protein/kcal), 62, 74, 85, 100, 108, for 60 days. The level of crude protein ranged from approximately 26% to 44% while the energy content remained constant at about 4.1 kcal g⁻¹. Growth ranged from 3.63 to 12.33 mg day⁻¹. The growth of abalone fed the 100 and 108 diets was significantly greater than that of each of the other diets. Protein efficiency ratio increased as the dietary protein content increased except for the T108 diet (44% crude protein). Abalone apparently consume food to satisfy an energy requirement. Caloric expenditure due to metabolism was estimated for abalone fed diets with protein ratios of 62, 85, 100. Energy loss due to respiration did not vary appreciably among abalone fed the different diets. The proportional distribution of dietary energy into fecal, digestible, growth, and metabolic energy was estimated for abalone fed these diets. Apparent dry matter digestibility was among the lowest for abalone fed the 100 P:E diet, but growth of abalone fed this diet was significantly higher than that of each of the other treatments except the 108 diet. Unexplained energy loss to achieve balance ranged from 7% to 28.5%, some of which is probably due to differential mucus and ammonia production. Results suggest a potential for the reduction of both dietary protein and lipid without causing any adverse effects on the growth response.     

Simulation model of within-herd transmission of bovine tuberculosis in Argentine dairy herds

Transmission of bovine tuberculosis was quantified in three dairy herds located in south Santa Fe Province, Argentina. Using estimates of Mycobacterium bovis transmission (β) and a Reed–Frost simulation model, the prevalence of tuberculosis infection in the study herds over time was investigated. The Reed–Frost model was modified by incorporating randomness in both β and the incubation period () of M. bovis. The mean estimated herd β was 2.2 infective contacts per year and did not differ significantly between the study herds. Modeling as Poisson distributed (mean 24 months) best fit the observed prevalences. Infection was predicted by the model either to spread quickly (<10 years) within a herd and reach a high prevalence (>50%), or to persist at a low prevalence (<5–10%). The model was robust, predictions were realistic and the mean β estimated was consistent with previous studies of bovine tuberculosis.     

Evaluation of Protein Quality in Microbound Starter Diets Made with Decapsulated Cysts of Artemia and Fishmeal for Fish Larvae

Abstract.— The protein quality of carboxymethylcellulose microbound diets (MBDs) made with decapsulated cysts of Artemia andlor fishmeal as protein sources was used as an indicator of their suitability as starter feed for fish larvae. Studies on the proximate, fatty acid and amino acid composition. in vitro protein digestibility. diet solubility, and protein structure were combined with an in vivo feeding experiment with African catfish Clarias gariepinus larvae to evaluate the protein quality of the MBDs and a commercial diet. The growth of catfish larvae was higher when fed Artemia -based MBDs than with fishmeal-based MBDs, despite the higher protein and amino acid content of the latter. The in vitro protein digestibility was high for all the MBDs in comparison to a commercial diet. Differences were found in the protein molecular weight among the diets. Most of the proteins in the fishmeal-based diets had low molecular weight in the range between 7.4 and 49.2 kDa. The Artemia-based MBDs had larger protein fractions between 29.4 and 82 kDa. Decapsulated cysts improved the utilization of the MBDs when used in combination with fishmeal. Besides the effect of chemical attractants, the explanation for the positive effect of Artemia has yet to be elucidated. However, attention should be given to interactions between nutrients (e.g., protein-lipid) in live food, which might have an effect on the functional properties of food proteins.     

Babesia odocoilei infection in elk

Two male North American elk from a commercial herd were evaluated because of a sudden onset of lethargy, anorexia, and voiding of red urine. These 2 elk were kept in the same pen as 4 other male elk that had died during the preceding 2 months. Laboratory analyses revealed anemia and intraerythrocytic parasites, later confirmed as Babesia odocoilei (a protozoal hemoparasite of cervids). Of the 240 elk remaining in the herd, 59 were screened for B odocoilei by microscopic evaluation of blood smears, protozoal culture of blood, and immunofluorescent antibody testing of serum. Of those 59 elk, 34 (58%) were infected with B odocoilei. Babesia odocoilei infection in elk can be fatal and should be considered in cases of sudden death or acute hemolytic anemia. Familiarity with the disease in elk is essential for practitioners because of the increasing popularity of commercial elk farming.     

Field evaluation of a coproantigen enzyme-linked immunosorbent assay for diagnosis of canine echinococcosis in a rural Andean village in Peru

One hundred and six dogs (61 males and 45 females) were examined for Echinococcus granulosus infection in a farming cooperative in the central highlands of Peru during November 1998. Canine echinococcosis was diagnosed using direct microscopic examinations of purged feces following arecoline purging and a coproantigen-detection enzyme-linked immunosorbent assay (ELISA) for E. granulosus. Mean age was 2 years with a range of 3 months to 9 years. The overall prevalence of canine echinococcosis using the ELISA test was 79% (84/106). Seventy-four dogs were successfully purged with arecoline. The frequency of canine echinococcosis was 82 (61/74) and 34% (25/74) by the coproantigen ELISA test and arecoline purging, respectively. The sensitivity and specificity of the coproantigen ELISA test was 88 and 95%, respectively. We found this assay to be especially advantageous in remote geographical areas. In future control programs against echinococcosis in Peru and other areas where E. granulosus is endemic the coproantigen ELISA should be used for the surveillance of the dog population.     

Molecular epidemiology of environmental MRSA at an equine teaching hospital: introduction,circulation and maintenance

The role that environmental contamination might play as a reservoir and a possible source of Methicillin-resistant Staphylococcus aureus (MRSA) for patients and personnel at equine veterinary hospitals remains undefined, as the environment has only been monitored during outbreaks or for short periods. Therefore, the objectives of this study were to determine the monthly presence, distribution, and characteristics of environmental MRSA at an equine hospital, and to establish patterns of contamination over time using molecular epidemiological analyses. For this purpose, a yearlong active MRSA surveillance was performed targeting the environment and incoming patients. Antimicrobial susceptibility testing, SCCmec typing, PFGE typing, and dendrographic analysis were used to characterize and analyze these isolates. Overall, 8.6% of the surfaces and 5.8% of the horses sampled were positive for MRSA. The most common contaminated surfaces were: computers, feed-water buckets, and surgery tables-mats. Ninety percent of the isolates carried SCCmec type IV, and 62.0% were classified as USA500. Molecular analysis showed that new pulsotypes were constantly introduced into the hospital throughout the year. However, maintenance of strains in the environment was also observed when unique clones were detected for 2 consecutive months on the same surfaces. Additionally, pulsotypes were circulating throughout several areas and different contact surfaces of the hospital. Based on these results, it is evident that MRSA is constantly introduced and frequently found in the equine hospital environment, and that some contact surfaces could act as “hot-spots”. These contaminated surfaces should be actively targeted for strict cleaning and disinfection as well as regular monitoring.     

Panagrellus redivivus mass produced on solid media as live food for Litopenaeus vannamei larvae

The free‐living soil nematode Panagrellus redivivus is well known to be an excellent food source for first feeding fish larvae. It represents an alternative to the highly expensive Artemia, which is commonly used. The lack of a proper method for mass production of P. redivivus has prevented its wider use in commercial hatcheries. A new cultivation method allows the production of a sufficient quantity of nematodes to deliver a standardized and permanently available live food of high quality, throughout the larval rearing period. In two experiments – carried out at the Centro de Investigación en Alimentación y Desarrollo, Mexico – several feeding regimes were established to prove the quality of the mass produced P. redivivus for larvae of Litopenaeus vannamei, the Pacific white shrimp. Two different nematode treatments were compared with a no‐feed group and a control group that was fed with Artemia. All treatments had an additional algal co‐feed and were run in five replicates. Panagrellus redivivus was cultured on two different media (wheat/corn flour and oat flour) to compare these for their suitability as high‐quality live food for the larvae. Shrimp fed nematodes grown on wheat/corn medium reached the postlarval stage earlier than those from other treatments. The nematode treatments showed promising results; however, further research is needed on the development of improved culture media or enrichment methods to further increase the nutritional value of P. redivivus.