Production and oxidation of wool grease after shearing

OBJECTIVE: To measure the production and amount of oxidation of wool grease secreted immediately after shearing. To identify components of wool grease that might act as a carrier to facilitate lateral diffusion of topically applied insecticides. DESIGN: Fine-wool Merino sheep were shorn and residual greasy wool was collected from the sheep's flank. The quantity of grease produced, and the amount of oxidation was measured during 18 days after shearing. Wool grease was fractionated into five component groups based on their polarity and the degree of oxidation in these fractions determined. RESULTS: There was a 24% increase in grease production within 2 days after shearing but secretions returned to pre-shearing amounts after 4 days. During this period wool grease oxidized rapidly. Of the grease fractions examined, sterol and wax esters remained essentially unoxidized whereas free sterols such as cholesterol and lanosterol, fatty acids and polar lipids, aldehydes and alcohols were extensively oxidized within 7 days after shearing. CONCLUSION: The transient increase in grease production after shearing may facilitate diffusion of topically applied synthetic pyrethroid insecticides. Oxidation of grease components may then contain the insecticide and limit further diffusion. Incorporating the insecticide in non-oxidising fractions of wool grease may make insecticide dispersion more efficient.     

The effects of body composition on the pharmacokinetics of subcutaneously injected ivermectin and moxidectin in pigs

Macrocyclic lactones are characterized by their long persistence in animals because of their extensive distribution into fat. This study examined the influence of body condition on the disposition of ivermectin (IVM) and moxidectin (MXD) in blood and fat following subcutaneous (s.c.) drug administration. 'Fat' and 'thin' lines of pigs were established using two different diets. All animals were then injected with either MXD or IVM at 300 microg/kg and blood samples were taken at regular intervals until slaughter. Two IVM-treated animals from each diet group were slaughtered at either 3 days or 3 weeks posttreatment. Two MXD-treated animals from each diet group were slaughtered at 3 days, 3, 6 or 9 weeks after treatment. Samples of backfat were taken from all animals at slaughter. Fluorescence HPLC was used to determine the concentrations of MXD or IVM in the plasma and fat samples. The plasma IVM concentration peaked more rapidly in the thin IVM treated pigs compared with the fat pigs. The concentration of IVM in backfat was significantly lower in the thin animals slaughtered 3 weeks after treatment. The MXD plasma concentration peaked within the first hour in both the thin and fat groups, but from 12 h posttreatment there was a higher MXD concentration in the plasma of the fat pigs resulting in MXD being detectable in these pigs for 28 days compared with only 17 days in the thin pigs. Despite this difference in plasma persistence no differences were seen in the MXD concentration of backfat between fat and thin animals. Body condition influenced the kinetic disposition of IVM and MXD following s.c. drug administration with both drugs being less persistent in thin compared with fat animals.     

Simultaneous Flow Cytometric Analysis of Phagocytosis and Oxidative Burst Activity in Equine Leukocytes

This paper describes a method for simultaneously measuring phagocytosis and oxidative burst activity in equine peripheral blood leukocytes by flow cytometry. Opsonized propidium iodide-labelled Staphylococcus aureus (PI-Sa) was used to measure the uptake of bacteria by equine phacocytes and the oxidative burst activity by oxidation of dihydrorhodamine 123. The requirements to achieve optimal activity of phagocytosis and oxidative burst are described. The advantage of the simultaneous technique is that it provides both independent and comparative values for phagocytosis and the oxidative burst, for the detection of impaired mechanisms of microbial destruction. Furthermore, the technique allows evaluation of opsonization activity in this context.     

Metabolite concentrations in plasma following treatment of cattle with five anthelmintics

Plasma concentrations of anthelmintics and their metabolites were determined after cattle were treated at recommended dose rates and routes of administration. Fenbendazole, oxfendazole, febantel, albendazole and thiabendazole were given orally and oxfendazole was also administered with an intraruminal injector. After fenbendazole, oxfendazole and febantel were administered, fenbendazole, oxfendazole and fenbendazole sulphone were all detected in plasma in each case. However, there were marked differences between the three anthelmintics in the peak concentrations and areas under the plasma concentration/time curve (AUC) of these three metabolites. Intraruminal administration of oxfendazole produced higher AUC for fenbendazole and fenbendazole sulphone than did oral administration. Albendazole sulphoxide and sulphone were detected in cattle plasma after albendazole administration but no parent drug was present. These metabolites disappeared more rapidly in cattle than has been reported for sheep. Only 5(6)hydroxythiabendazole was detected in cattle plasma after thiabendazole treatment.     

Use of random pattern skin flaps for wound closure in two horses

A 9-year-old Thoroughbred broodmare presented with a mass rostral to the medial canthus of the left eye. The mass was removed under general anaesthesia and the wound bed infiltrated with carboplatin emulsion before partially closing using a Z-plasty. The mass recurred and subsequently was resected twice. It has not recurred 68 weeks post-treatment. The second case describes removal of a granulomatous mass from the metatarsus of a yearling Thoroughbred colt. Skin expanders and a rotational flap were used to allow tension-free closure. This required two separate surgeries to firstly insert the skin expanders and secondly to remove the mass, the expanders and to close the defect. The wound healed with good cosmesis. There have been few reports on the use of skin flaps in equine reconstructive surgery in the last 30 years. This report details two cases of wound closure where skin flaps were used to achieve primary intention wound healing.     

Olfactory responses of Argentine stem weevil to herbivory and endophyte-colonisation in perennial ryegrass

Journal of Pest Science - Argentine stem weevil adults (ASW, Listronotus bonariensis) feed on the leaves of agricultural grasses and their larvae mine the pseudostem, causing extensive damage that...     

The use of antibiotics on small dairy farms in rural Peru

Very little is known about the use of antibiotics on small dairy farms in lower/middle-income countries. The use of these drugs can have profound impacts on animal health, farmer income and public health. A survey of 156 farmers was conducted in Cajamarca, a major dairy-producing center in the highlands of Peru characterized by small farms (<15 cows) to assess patterns and determinants of antibiotic use and farmers’ knowledge of antibiotics. The reported incidence of disease on these farms was relatively low (0.571 episodes of disease per cow-year), but more than 83% of the reported episodes were treated with antibiotics. The most commonly used antibiotics were oxytetracycline, penicillin and trimethoprim-sulfamethoxazole drugs; antiparasitic drugs were also used to treat what were likely bacterial infections. An increased incidence of treated disease was significantly associated with smaller farm size, lower farmer income, the previous use of the Californian Mastitis test on the farm and antibiotic knowledge. Farmers’ knowledge of antibiotics was assessed with a series of questions on antibiotics, resulting in a “knowledge score”. Increased knowledge was significantly associated with the use of antibiotics for preventative reasons, the purchase of antibiotics from feed-stores, the experience of complications in animals after having administered antibiotics, the number of workers on the farm and the educational level of the farmer. Overall, antibiotics appeared to be used infrequently, most likely because therapeutic interventions were sought only when the animal had reached an advanced stage of clinical disease. Few farmers were able to define an antibiotic, but many farmers understood that the use of antibiotics carried inherent risks to their animals and potentially to the consumers of dairy products from treated animals. The results of this study are useful for understanding the patterns of antibiotic use and associated management, demographic and knowledge factors of farmers on small dairy farms in rural Peru.     

Microparticle dispensers for the controlled release of insect pheromones

The potential utility of micrometer-sized particles as controlled-release devices for the volatilization of insect pheromones for mating disruption applications is evaluated in this study for two pheromone/model compound systems (codlemone/1-dodecanol and disparlure/1,2-epoxyoctadecane). To expedite the measurement of release rates from these particle devices, two techniques based on thermogravimetric analysis (TGA) have been exploited: isothermal TGA (I-TGA) at elevated temperatures (40-80 degrees C) with N(2) convection and volatilization temperature (VT) by dynamic TGA. A correlation between these two methods has been established. Samples that exhibit a higher VT provide a lower release rate from a particle substrate. Using these techniques, it has been demonstrated that chemical interactions between adsorbed liquids and particle surfaces may play a small role in defining release characteristics under conditions of low surface area, whereas parameters associated with total surface area and micropore structure appear to be much more significant in retarding evaporation for uncoated particles containing an adsorbed liquid. Additional regulation of release rates was achieved by coating the particle systems with water-soluble or water-dispersible polymers. By careful selection of particle porosity and coating composition, it is envisioned that the evaporation rate of pheromones can be tailored to specific insect control applications.     

Where are the food animal veterinarian shortage areas anyway?

In 2010 the United States implemented the Veterinary Medicine Loan Repayment Program (VMLRP) to address perceived regional shortages in certain veterinary occupations, including food animal practice. With county as the unit of analysis, this paper describes a pair of models to evaluate factors associated with being designated a private practice shortage area in 2010. One model is used to explain food animal veterinarian location choices so as to provide an objective evaluation of comparative shortage. The other model seeks to explain the counties chosen as shortage areas. Model results are then used to evaluate the program. On the whole the program appears to perform quite well. For several states, however, VMLRP shortage designations are inconsistent with the food animal veterinarian location model. Comparative shortage is generally more severe in states that have no VMLRP designated private practice shortage counties than in states that do.     

The effect of the nitrification inhibitor dicyandiamide (DCD) on spring and annual herbage production in urine patches when applied in late summer or early autumn

A cut plot experiment was undertaken at two sites in Ireland, one a free‐draining acid brown earth at Moorepark (MPK) and the other a fine loam soil with imperfect drainage at Johnstown Castle (JC). The effect of applying the nitrification inhibitor dicyandiamide (DCD) at 10 kg ha^?1 in July, August and September or not applying DCD to plots receiving synthetic urine or zero urine on spring and annual herbage production was examined. In the experiment, each site received 350 kg nitrogen (N) fertilizer ha^?1 year^?1. The application of DCD in August at a rate of 10 kg ha^?1 significantly increased spring and annual herbage production by 14 and 15%, respectively, at MPK, when applied following urine application in year 1. There was no effect of DCD applied in year 1 on herbage production at JC. The application of DCD in August resulted in lower soil total oxidized N (TON) content up to sampling day 56 post‐urine application, at MPK in year 1, retaining higher N content in the soil. There was no effect of DCD on any of the parameters measured in year 2 at MPK or at JC. Urine application did not increase spring herbage production at either site. Urine application significantly increased annual herbage production at MPK only in year 1. Urine application increased annual herbage N uptake, herbage crude protein (CP) content and soil mineral N at both sites in both years.