Development and delivery of evidence-based messages to reduce the risk of zoonoses in Nairobi, Kenya

This paper describes a trans-disciplinary process of co-generating and disseminating evidence-based messages for reducing the risk from cryptosporidiosis and other zoonoses in an urban community in Nairobi. Research findings about disease prevalence, risk factors and observed risky and risk-mitigating practices were analysed by a team comprising researchers, community members and local policy- and decision-makers. Using participatory planning, multiple strategies were developed for disseminating key information. We identified five vulnerable groups at higher risk of exposure to cryptosporidiosis and other cattle zoonoses with similar transmission pathways (women, children, elderly people, immunosuppressed people and male farm workers). For each group, targeted messages were developed. Good practices already in use, as were also practices as practices to improve environmental conditions. These messages were disseminated through printed material, in a workshop, through community campaigners and also an edutainment soap opera episode broadcast on Kenyan television. In conclusion, a participatory and trans-disciplinary process can help transform the findings of research into messages that are targeted, attractive and understandable.     

Adding nutritional value to meat and milk from pasture-fed livestock

Staple meat and milk provide excellent nutrition, but when traditional foods and ingredients are tailored to meet the particular nutritional or lifestyle demands of a population they become even more attractive and valuable. These foods can be considered as delivery systems for health-promoting nutrients. Nutritional improvement of meat and milk can be achieved several ways, preferably by making desirable changes on-farm to directly improve the food without subsequent manipulations. Scope for these changes is limited by animal homeostasis, but alternatives may be less desirable. Methods in vivo that suit typical pastoral farming practice and can complement the solving of animal health and production problems include: selection of traits or phenotypes; specialty diets; long-acting parenteral supplements; and modification of ruminal microflora. Successful techniques to increase the concentration of calcium, selenium, iodine and iron in milk or meat are described. Manipulations to change composition are only one part of bringing tailored foods to market. Commercial realisation of these new products needs the initiative and collaboration of scientists, veterinarians, growers and producers responding to market pull. The uptake of future biotechnologies to capture more value inside the farm gate will also be required if the pastoral industry in New Zealand is to sustain a global competitive advantage.     

Changes in serum concentrations of methylmalonic acid and vitamin B12 in cobalt-supplemented ewes and their lambs on two cobalt-deficient properties

AIM: To determine concurrent changes in serum methylmalonic acid (MMA) and vitamin B12 concentrations of ewes and their lambs on cobalt-deficient properties, subsequent to cobalt supplementation. METHODS: Three experiments were carried out on two farms. Groups of ewes (n=25-50) were either supplemented with cobalt bullets during late pregnancy, 23-47 days before the mean lambing date, or left unsupplemented. In two experiments, lambs from within each group were supplemented directly by vitamin B12 injection at 3-weekly intervals from birth, and in the third experiment by injection with micro-encapsulated vitamin B12 at tailing and 3 months later. Pasture samples were obtained for analysis of cobalt content at each sampling time. Blood samples were obtained and liveweight recorded from ewes and lambs at approximately monthly intervals. On one farm (two experiments), liver and milk samples were obtained from ewes and liver samples from lambs. RESULTS: Serum vitamin B12 concentrations in unsupplemented ewes fell below 250 pmol/L during early lactation in all experiments and mean concentrations as low as 100 pmol/L were recorded. MMA concentration was maintained below 2 micromol/L in serum from supplemented ewes but increased to mean concentrations ranging from 7 to 14 micromol/L at the nadir of serum vitamin B12 concentration during peak lactation. A significant liveweight response to supplementation was recorded in ewes on one property, and the vitamin B12 concentration in the ewes' milk and in the livers of their lambs more than doubled. No liveweight-gain response to supplementation was observed in lambs on this property. Mean serum MMA concentrations in lambs ranged from <2 in supplemented, to 19.2 micromol/L in unsupplemented lambs, and the latter had concurrent serum vitamin B12 concentrations of >300 pmol/L. Pasture cobalt concentration was lowest at 0.04-0.09 microg/kg dry matter (DM) on the property on which responses in lambs occurred but considerably higher (>0.09 microg/kg DM) on the property on which responses in ewes occurred. On the second property, serum vitamin B12 concentrations in lambs at tailing were extremely low (100 pmol/L), irrespective of supplementation of dams with cobalt. Mean serum MMA concentration was increased to 20 and 42 micromol/L in lambs from supplemented and non-supplemented ewes, respectively. Weight-gain response to direct supplementation of lambs with vitamin B12 occurred during suckling in the latter, but not the former. Lambs from ewes supplemented with vitamin B12 showed a much bigger increase in serum vitamin B12 concentrations a month after supplementation than did lambs from unsupplemented ewes (+1,400 pmol/L vs + 650 pmol/L). CONCLUSIONS: Serum MMA concentration gave a more precise indication of responsiveness to vitamin B12 or cobalt supplementation than serum vitamin B12 concentrations in ewes and lambs. Neither very low serum vitamin B12 nor elevated MMA concentrations were necessarily indicative of responsiveness to supplementation in suckling lambs, but the latter gave an early indication of impending responsiveness. Supplementation of the ewe with a cobalt bullet appeared to protect the growth performance of the lamb for 90 days and influence the subsequent serum vitamin B12 response in the lamb to vitamin B12 supplementation. CLINICAL SIGNIFICANCE: Supplementing ewes with cobalt bullets in late pregnancy can improve the vitamin B12 status of their lambs, and modify their response to vitamin B12 supplementation.     

Structure-based carbon nanotube sorting by sequence-dependent DNA assembly

Wrapping of carbon nanotubes (CNTs) by single-stranded DNA (ssDNA) was found to be sequence-dependent. A systematic search of the ssDNA library selected a sequence d(GT)n, n = 10 to 45 that self-assembles into a helical structure around individual nanotubes in such a way that the electrostatics of the DNA-CNT hybrid depends on tube diameter and electronic properties, enabling nanotube separation by anion exchange chromatography. Optical absorption and Raman spectroscopy show that early fractions are enriched in the smaller diameter and metallic tubes, whereas late fractions are enriched in the larger diameter and semiconducting tubes.     

Impact of iodine supplementation of dairy cows on milk production and iodine concentrations in milk

AIM: To determine the effect of iodine supplementation on milk production and iodine concentrations in milk for pasture-fed, seasonally calving dairy cows. METHODS: The study was run over two consecutive seasons on the same dairy farm. In Trial One, 294 Friesian dairy cows were either untreated or injected intramuscularly three times with iodised oil (2,370 mg iodine/dose) at the start of lactation (Day 1) and at about 100-day intervals thereafter. Iodine concentrations in milk were determined prior to each injection on Days 1, 98 and 210, and milk, fat and protein yields measured on Days 43, 98, 176 and 238. In Trial Two, 234 Friesian dairy cows were either untreated or injected intramuscularly with iodised oil (2,370 mg iodine/dose) in early lactation (Day 1) and 99 days later. Iodine concentrations in milk were determined prior to treatment on Days 1, 55 and 161. Serum thyroxine (T4) and triiodothyronine (T3) concentrations were determined in the latter two samples and milk, protein and fat yields were determined on Days 25, 119, 182 and 221. In both trials, pasture was sampled at 1- or 3-monthly intervals and iodine concentrations in herbage measured. RESULTS: Iodine concentrations in pasture averaged 0.24 mg/kg dry matter (DM) in both seasons and varied little over the experimental period. Iodine concentrations in milk from unsupplemented cows were <20 microg/L in both trials. Three iodine injections at about 100-day intervals increased iodine concentrations in milk to 58 microg/L for at least 98 days after each treatment. Two iodine injections at about 100-day intervals raised milk iodine concentrations to 160 microg/L and 211 microg/L at least 55 days after each treatment, but had no effect on serum thyroid hormone concentrations. Iodine supplementation had no significant effect on milk, milkfat or milk protein yield. CONCLUSIONS: Pastures in New Zealand that contained 0.24 mg iodine/kg DM appeared to provide an adequate iodine intake for dairy cows. Intramuscular injections of iodine resulted in significant increases in iodine concentrations in milk. CLINICAL SIGNIFICANCE: Increasing iodine concentrations in milk via intramuscular injection of iodine could provide a method for significantly increasing iodine intakes of humans, in particular, children.     

Changes in liver copper concentration of thoroughbred foals from birth to 160 days of age and the effect of prenatal copper supplementation of their dams

OBJECTIVES: To monitor the change in liver copper concentration of Thoroughbred foals from birth to 160 days of age and to determine the effects of supplementation by two injections of copper edetate given to dams in late gestation on the liver copper concentration of their foals at birth. PROCEDURE: Ten mares pregnant to the same stallion were randomised into two groups on the basis of age, liver copper concentration and expected foaling date. The treatment group mares were given 100 mg and 250 mg copper edetate intramuscularly during the ninth and tenth months of gestation respectively. Foals had liver biopsies taken weekly in the first month of life, then monthly for four months. Foals were euthanased at 160 days of age; liver samples were taken and the copper concentrations were determined. RESULTS: Two distinct patterns of age dependent decline in liver copper concentration were evident. The mean (+/- SD) liver copper concentration of the foals was high at birth (374 +/- 130 mg/kg DM), and for seven it declined to adult values by 160 days of age (21 +/- 6 mg/kg DM). In three foals the decline was at a slower rate than in the other seven and at 160 days of age the mean concentration was 162 +/- 32 mg/kg DM. Repeated measures analysis showed significant differences between each biopsy (P < 0.01) and between 'normal' and 'accumulator' foals (P < 0.002). Copper injections given to mares in late pregnancy had no effect on the liver copper concentration of foals at birth. CONCLUSIONS: The significance of the two patterns of age dependant decline in liver copper concentration is unknown. Parenteral copper supplementation of the dam in late gestation had no effect on the liver copper concentration of the foal at birth.     

Extended summaries: Physicochemical and biophysical panel symposium enhancing pesticide action through mixtures

The following are summaries of papers presented at a meeting of the Physicochemical and Biophysical Panel of the Pesticides Group held on 14 October 1986 at the Society of Chemical Industry, 14 Belgrave Square, London SWIX8PS. The papers published here are entirely the responsibility of the authors and do not reflect the views of the Editorial Board of Pesticide Science.