Feeding behavior of feedlot lambs fed diets containing levels of cassava wastewater

In this study, we evaluated the effects of including cassava wastewater in the diet on the feeding behavior of feedlot lambs in 35 male uncastrated Santa Inês × Dorper crossbred lambs at an approximate age of 3 months, with an average live weight of 20.0?±?3.4 kg. Diets were formulated with hay of cassava shoots (roughage) and a concentrate based on corn and soybean, with a roughage:concentrate ratio of 50:50, plus inclusion of cassava wastewater at the levels of 0, 12, 24, 36, or 48 g/kg of the total diet. Feeding behavior was evaluated between the 46th and 52nd days of the experiment. Increasing cassava wastewater levels in the diet reduced (P?<?0.05) the intakes (kg/day) of dry matter and neutral detergent fiber as well as the efficiency of rumination (g/cud and g/h) of dry matter and neutral detergent fiber. The other behavioral parameters were not affected by wastewater inclusion in the diet. Therefore, the inclusion of up to 48 g/kg of cassava wastewater on fresh matter of diets is not recommended for feedlot lambs.     

Structure–activity relationships of eugenol derivatives against Aedes aegypti (Diptera: Culicidae) larvae

BACKGROUND: Dengue fever is a severe public health problem for several countries. In order to find effective larvicides to aid control programs, the structure‐activity relationships of eugenol derivatives against Aedes aegypti (Diptera: Culicidae) larvae were evaluated. Additionally, the composition and larvicidal activity of Syzygium aromaticum essential oil was assessed. RESULTS: Four compounds representing 99.05% of S. aromaticum essential oil have been identified. The essential oil was active against Ae. aegypti larvae (LC₅₀ = 62.3 and 77.0 ppm, field‐collected and Rockefeller larvae respectively). The larvicidal activity of eugenol, the major compound of the essential oil, was further evaluated (LC₅₀ = 93.3 and 71.9 ppm, field‐collected and Rockefeller larvae respectively). The larvicidal activity and structure‐activity relationships of synthetic derivatives of eugenol were also assessed. The larvicidal activity of the derivatives varied between 62.3 and 1614.9 ppm. Oxidation of eugenol allylic bond to a primary alcohol and removal of the phenolic proton resulted in decreased potency. However, oxidation of the same double bond in 1‐benzoate‐2‐methoxy‐4‐(2‐propen‐1‐yl)‐phenol resulted in increased potency. CONCLUSION: Structural characteristics were identified that may contribute to the understanding of the larvicidal activity of phenylpropanoids. The present approach may help future work in the search for larvicidal compounds. Copyright © 2012 Society of Chemical Industry     

Are antigen test kits efficient for detecting heartworm-infected dogs at the southern distribution limit of the parasite in South America? Preliminary results

The aim of this study was to evaluate the performance of commercial heartworm antigen tests in dogs harbouring Dirofilaria immitis microfilariae near its distribution limit in South America. A total of 4934 blood samples of adult dogs from Southern Greater Buenos Aires were examined to detect circulating microfilariae in the buffy coat interface between December 2005 and April 2006. Microfilariae were detected in 88 (1.8%) blood samples and all the microfilariae observed were identified as D. immitis by acid phosphatase stain technique. In a first trial, 69 (78.4%) out of the 88 serum were positive by Speed((R)) Diro. Then, a new test was performed over 25 microfilariae-positive serum samples randomly selected among the 88 previously tested samples and using simultaneously Speed((R)) Diro, Witness((R)) Dirofilaria and Snap((R)) 3dx. This second trial showed identical results for the three different tests, in which 19 (76%) samples were positive. Therefore, more than 20% of microfilaremic dogs were antigen negative. The main hypothesis that could explain our finding is a low worm burden in the study area. According to our preliminary results, it is highly recommendable the complementary use of antigen tests and other procedures to obtain an accurate diagnostic near the distribution limit of the parasite.     

Settling of insecticide from dip wash mixed with dam water and zinc sulphate and used to control sheep lice (Bovicola ovis)

SUMMARY Insecticidal dipping fluid emulsions, mixed in vitro in dam water containing suspended clay particles and 1% w/v zinc sulphate, were analysed to determine rates of settling of diazinon, cyhalothrin and cypermethrin. Fifteen minutes after mixing, the concentration of the insecticides 5 cm below the surface had declined by 72.5%, 72.8% and 89.4%, respectively. On remixing, the concentration of insecticide in suspension was close to or greater than the initial concentration. In 2 trials, lice were eradicated from sheep showered with dip wash mixed in cloudy dam water to which 1% w/v of zinc sulphate was added. In 12 flock treatments in which 1000 to 2000 sheep were dipped with added zinc sulphate, the concentration of insecticide remained above the minimum lethal for susceptible strains of lice. However, lice were still present 6 months later in 8 of these flocks. When zinc sulphate is added to dip wash, agitation is needed to maintain the insecticide in suspension.     

Henneguya corruscans n. sp. (Myxozoa,Myxosporea, Myxobolidae), a parasite of Pseudoplatystoma corruscans (Osteichthyes,Pimelodidae) from the Paraná River,Brazil: A morphological and morphometric study

This paper describes the parasite Henneguya corruscans n. sp. which infects the gills of Pseudoplatystoma corruscans Spix and Agassiz, 1829 found in the Paraná River, Brazil. The parasites belong to the interlamellar-epithelial type as defined by Molnár (2002) [Molnár, K., 2002. Site preference of fish myxosporeans in the gills. Dis. Aquat. Org. 48, 197–207]. The spores examined had thin, smooth walls with symmetric valves; the total length of the spores was 27.6 (25–29) μm. The spore body was ellipsoidal in frontal view and biconvex in lateral view and they measured 14.3 (13–15) μm long by 5 μm wide and 4 μm in thickness. The polar capsules were small and elongated, equally sized, with a rounded posterior extremity and tapering anteriorly, and they corresponded more or less the half the length of the spore body; they were 6.8 (6–7) μm long by 2 μm wide, and the polar filament formed 5–6 coils obliquely to the axis of the polar capsule. The tail was 13.7 (12–15) μm long and bifurcated shortly after the end of the spore body. The importance of the infection for the farming of P. corruscans is discussed.     

Molecular characterization of Portuguese strains of Yersinia ruckeri isolated from fish culture systems

A total of 23 Portuguese strains of Yersinia ruckeri , the causative agent of enteric redmouth disease (ERM), were comparatively studied by means of lipopolysaccharide (LPS) and outer membrane protein (OMP) analysis, plasmid profiling and ribotyping in order to investigate the heterogeneity among isolates and the usefulness of these methods as epidemiological markers. Only two LPS profiles were observed among the isolates studied, corresponding with the serotypes O1 and O3 of Y. ruckeri . A higher heterogeneity was detected analysing the OMP, seven different patterns being observed. Although some isolates carried different small plasmids, all the serotype O1 isolates showed a plasmid band of 50 MDa and all the serotype O3 strains shared in common a extrachromosomic DNA band of 30 MDa. The analysis of the ribopatterns obtained using three different enzymes, separated the strains into 10 ribotypes, indicating genetic heterogeneity among the isolates. The heterogeneity was greater within serotype O1 isolates, six ribotypes being detected, than within serotype O3 in which only three ribotypes were found. Although OMP analysis and ribotyping can be useful for the differentiation of strains on the basis of farm and/or season of isolation, we consider that ribotyping is the best candidate for epidemiological studies because it is easier to perform and offers a slightly better discriminative power.     

Health status of two salmonid aquaculture facilities in North Portugal: characterization of the bacterial and viral pathogens causing notifiable diseases

A comparative bacteriological and virological survey was conducted in two fish farms in the North of Portugal. The fish species examined included cultured rainbow trout, Oncorhynchus mykiss (Walbaum), and brown trout, Salmo trutta L., as well as wild fish captured near both facilities. The microbial load in the internal organs of apparently healthy fish was nonitored over a year, an all the disease problems occurring during this period were investigated. Although both farms presented intermediate levels of infection(30–40% infected fish), farm B showed the poorest microbiological quality since constant but low mortalities were observed throughout the year. Flavobacterium and Psedomonas-Xanthomonas were the predominant bacterial groups, comprising around 40–50% of the isolates from each farm. In farm B, members of the Enterobacteriaceae and mortile Aeromonas also showed significant prevalence (about 20%). The only outbreak of a notifiable disease was an occurrence of furunculosis, caused by Aeromonas salmonicida subsp. salmoncida, in farm A. However, Yersinia ruckeri was isolated not only from diseased fish, but also from asymptomatic fish, usually in mixed infections with motile Aeromonas or infections with motile Aeromonas or infectious pancreatic necrosis virus (IPNV). While Y. ruckeri isolates associated with mortalities belonged to the serotype O1 (subgroup a), those isolated from asymtomatic fish corresponded to serotype O3. Two strains of IPNV (serotype Ab) were isolated in farm B, which represents the first viral agent detected in Portuguese aquaculture. Qualitative and quantitative differences in microbial load were observed between cultured and wild fish. No notifiable bacterial or viral pathogens were detected in any of the feral species studied.     

Epidemiology of canine heartworm in its southern distribution limit in South America: Risk factors, inter-annual trend and spatial patterns

This study was aimed at understanding some aspects of the canine heartworm epidemiology in the southern distribution limit of the parasite in South America. With this objective, 19,298 blood samples of owned dogs from 65 localities of 13 municipalities of Buenos Aires Province were tested for Dirofilaria immitis circulating microfilariae and/or female antigens. The overall heartworm prevalence was 1.63% by microhematocrit tube technique (n=19,136), 3.65% by modified Knott (n=713), and 14.41% by antigen test kit (n=118). Microfilaremic dogs showed a median of 1933 microfilariae per millilitre (q1=375, q3=5625, n=100). Male dogs belonging to breeds of short hair and large size recorded significantly higher prevalences than the other categories. Also, the prevalence increased significantly with the age and only dogs younger than 12 months were not found infected. A clear decreasing trend of the annual prevalence was observed during the whole study period, from 3.91% in 2001 to 1.17% in 2006. D. immitis-infected dogs were detected in 32 localities of 9 municipalities (prevalence range: 0.2-6.7%). Generalized linear models were used to assess associations between heartworm prevalence and environmental variables. The resulting significant models were univariate and included variables related with soil cover and human population density. The best model predicted maximum heartworm prevalences around middle values of bare soil cover, and lower at high and low covers. According to our analyses, canine heartworm infection in urban temperate Argentina could be described as relatively low, endemic, and spatially heterogeneous. Host and environmental factors affecting heartworm transmission at local level were identified and discussed.     

Efficacy of some biodegradable films as pre-harvest covering material for guava

To produce guavas with good commercial or industrial potential, fruit farmers use phytosanitary practices such as fruit bagging. Bagging protects the fruit mainly from the attack of pests, such as the fruit fly (Anastrepha spp.) and the guava weevil (Conotrachelus psidii), and reduces the use of insecticides and fungicides. This investigation aimed to develop and produce biodegradable films from cassava starch and poly(butylene adipate-co-terephthalate) (PBAT) by extrusion for application in pre-harvest guava fruit bagging. After the fruit harvest, for 6–9 weeks all films were more fragile and rigid, but did not present cracks. BF70 was the most fragile and had the greatest tendency to tear; however, it remained whole until harvesting. Fruit bagged with films BF30, BF50, BF70 was analyzed for fruit quality and compared with PSF control and non-bagged fruit. There was no difference between the treatments relative to physical and chemical characteristics, indicating that biodegradable film did not influence fruit development when compared to the PSF control.