Lice and mite infestations of cattle in Iceland
The aim of the present study was to survey lice and mite species infesting cattle in Iceland and to evaluate their prevalence on farms, prevalence and site preferences on the animals and correlation with dermatological symptoms. The survey included two separate investigations, a combing study including 50 calves and 50 dairy cows, and a study of skin samples including 27 bullocks and 28 dairy cows. The animals came from farms in Southwest Iceland. In the combing study five preselected areas on each animal were combed. Two lice species were found, the chewing louse Bovicola bovis and the sucking louse Solenopotes capillatus. Lice were found at 7 of 10 farms. B. bovis was found at 50% and S. capillatus at 40% of the farms and both species occurred at 20% of the farms. Lice were found on 40% of the calves and 4% of the cows. B. bovis was found on 28% of the calves and 2% of the cows. S. capillatus was detected on 16% of the calves and 2% of the cows. B. bovis was most prevalent on back and rump, less prevalent on the head, neck and tail and was not detected on the front leg. S. capillatus was most prevalent on the neck, then head and front leg, and was least prevalent on the posterior back and rump and on the tail. Minor dermatological signs were seen on two cows and three calves. In the study of skin samples, samples were taken from five preselected sites of the animals. In this study the hair follicle mite Demodex bovis was found in the skin of the neck of one bullock (1.8%). No macroscopic skin disorders were observed on the samples.
Bovine Demodecosis: Treat to Leather Industry in Ethiopia
A cross-sectional study was conducted commencing October 2010 to June 2011 in and around Gondar, Amhara Regional State, Ethiopia with the objectives of assessing the economic impact; determine prevalence and extent of hide damage. A total of 384 cattle of all age, sex and breed OF were examined and deep skin scrapings with pus and ten hides were sampled. SPSS version 19 was used for data analysis. Higher prevalence was observed in cross breeds 15.75% than local breeds, 15.55%. The highest prevalence was observed from animals greater than 3 years of age, 48 (18.32%) while the lowest, 9 (0.96%) in those one to three years. 18.25 and 11.1% was recorded in female and male animals respectively. The spatial distribution of demodex on shoulder was 8.08 and 1.04% on ears and eyes respectively. Production system of semi- intensive and extensive managements was found almost affecting similarly with 13.66 and 13.43%, respectively. In lime-sulphide treated hides large nodules were prominent with dark contents; small non- protruding nodules, enlarged openings and ragged depressions near the grain surface were dipcted. In conclusion the highest overall prevalence (15.63%) of D. bovis infestation was recorded. This indicates that despite many efforts tried to study infectious diseases prevalence in the study area, demodicosis has been given lesser attention to be treated as a separate health problem. Therefore, Prevention and control measures should be taken rather than treating demodicosis.
Modelling of Mooney viscosity relaxation in natural rubber
Abstract Better assessment of natural rubber (NR) quality and processability, through the identification of new attributes, is still a major challenge. With this scope, 12 model samples of natural polyisoprene and two of synthetic polyisoprene were characterized in terms of Mooney torque relaxation, using the standardized ISO289 method (ML(1+4)100, explained later in the Section 1 ). The main purpose of this study was to identify a model that gave a better fit for the experimental decay of Mooney torque over time (ML(t)=f(t)) than the usual power law model used before (Y=at−b, [G.M. Bristow, A.G. Sears, The use of novel parameters in the assessment of natural rubber processability, NR Technol. 18 (1987); H.G. Burhin, W. Spreutels, J.M. Campbell, MV2000 Mooney viscometer: Mooney relaxation measurements on raw polymers and compounded rubber stocks, Kautsch. Gummi Kunstst. 43 (1990) 431]). The results showed that a generalized Maxwell model, and the Wu–Abbott empirical model ( Y = 1 − a Ln ( t ) − ( b t / ( c + t ) ) ) [T. Wu, J.A. Abbott, Firmness and force relaxation characteristics of tomatoes stored intact or as slices, Postharvest Biol. Technol. 24 (2002) 59–68], recently used for describing stress relaxation of tomato flesh, allowed a better description of the relaxation curve for the samples studied than the power law or stretched exponential traditionally used. Moreover, the total relaxation time (τm) given by the generalized Maxwell model showed good correlation with the total gel content of the samples studied.