Efficacy and stability of a novel silica supplement for improving bone development in broilers.

1. The essentiality of silicon for skeletal development has been established, but the adequacy of bioavailable silicon supply in broiler diets has not been considered for 30 years, despite average daily weight gain of birds increasing by almost a third over that time. Therefore, two studies were undertaken to investigate whether modern strains of broiler chicken benefit from diet supplementation with bioavailable silica. 2. Trial 1 was a 2x2x2 factorial study where six replicate pens of seven chicks were fed one of the eight freshly prepared diets from hatch to 21 days of age, with bodyweight gain and feed intake recorded weekly. Diets combined the following factors: silicon supplement fed at 0 ppm or 1000 ppm, phytase levels of either 0 FTU/kg or 1500 FTU/kg and either 0.6% or 0.7% Ca. Tibia were analysed for bone breaking strength, extent of tibial dyschondroplasia and feet measured for bone ash and pododermatitis score. 3. Trial 2 used a 0.7% Ca with 1500 FTU phytase diet as the control and compared this with the same diet containing either 1000 ppm silicon (MONO-Si) freshly added each week or 1000 ppm silicon added in a single, advance-prepared batch per feeding phase. Each diet was fed to nine pens of seven birds from 0 to 35 d with feed consumption and weight recorded weekly. Two birds per pen were euthanised on d 14, 21 and 35 and tibias collected for measurement of bone breaking strength, ash and mineral content. Serum was collected for Si content. 4. Univariate analysis of means from each trial showed that silica supplementation improved bird weight gain over the starter phase, though there was no effect on feed conversion. 5. Bone strength improved with added silica in both studies, without affecting bone mineral content; indicating that modern strains of broiler may require dietary supplementation with bioavailable silicon.

Bioavailability of a novel form of silicon supplement.

In this study, we assessed uptake and potential efficacy of a novel, pH neutral form of silicon supplement in vitro and using broiler chickens as a model species. In vitro bioavailability of this supplement was significantly higher than other commercial supplements tested, all of which claim available silica content. To confirm bioavailability of the new supplement in vivo, a broiler chick feeding trial reported blood uptake that was significantly higher than a Bamboo-derived silicon supplement. We assessed dose response of the novel supplement in a further study with increased dose related levels of silicon being detected in the blood and tibia. We found tibia and foot ash residue as a percentage of dry mass was higher with inclusion of the novel supplement in the diet, particularly in young birds and that this was followed by significant increase in tibia breaking strength. This novel supplement may therefore have applications in the improvement of bone integrity, with implications for the reduction of lameness in broilers. These results indicate the novel silica supplement is readily absorbed in chicks, and transported in the blood supply to sites such as the skeleton due to it being present in a non-condensed, monomeric form. There is potential for wider application of this silica supplement in other species where bone breakages are a problem, including high performance sport.

The macro-economic impact of a foot-and-mouth disease incursion in New Zealand.

The 2001 outbreak of Foot-and-Mouth Disease (FMD) in the United Kingdom heightened public concern in New Zealand about the economic consequences of an outbreak of FMD, and resulted in the Reserve Bank and Treasury conducting an assessment of the macro-economic impact of a small FMD outbreak in New Zealand. The study was based on a relatively small outbreak in which 50 properties were infected over a period of two months. Cumulative losses calculated over two years from the beginning of the hypothetical outbreak were estimated at around NZ dollars 10 billion, a figure twice as large as the initial Ministry of Agriculture and Forestry estimate. The main reason for this difference is that the Reserve Bank study included the additional macro-economic effects of a slump in domestic demand. The study also demonstrated that in New Zealand under the conditions of the current OIE Terrestrial Animal Health Code for FMD, the economic impact of any programme to control FMD by vaccination in which vaccinated animals are not slaughtered, is significantly worse than rapid eradication by stamping out.

Construction of silica-enhanced S-layer protein cages.

The work presented here shows for the first time that it is possible to silicify S-layer coated liposomes and to obtain stable functionalized hollow nano-containers. For this purpose, the S-layer protein of Geobacillus stearothermophilus PV72/p2 was recombinantly expressed and used for coating positively charged liposomes composed of dipalmitoylphosphatidylcholine, cholesterol and hexadecylamine in a molar ratio of 10:5:4. Subsequently, plain (uncoated) liposomes and S-layer coated liposomes were silicified. Determination of the charge of the constructs during silicification allowed the deposition process to be followed. After the particles had been silicified, lipids were dissolved by treatment with Triton X-100 with the release of previously entrapped fluorescent dyes being determined by fluorimetry. Both, ζ-potential and release experiments showed differences between silicified plain liposomes and silicified S-layer coated liposomes. The results of the individual preparation steps were examined by embedding the respective assemblies in resin, ultrathin sectioning and inspection by bright-field transmission electron microscopy (TEM). Energy filtered TEM confirmed the successful construction of S-layer based silica cages. It is anticipated that this approach will provide a key to enabling technology for the fabrication of nanoporous protein cages for applications ranging from nano medicine to materials science.

Persistent lymphocytosis and virus-like particles in lymphocytes of sheep inoculated with cell-free extracts derived from ovine malignant lymphomas.

White cell counts of sheep inoculated in utero or at birth with cell-free extracts of ovine malignant lymphomas have been monitored for 5 yr. Of 28 inoculated sheep which have survived, 19 have shown persistent lymphocytosis. After 5 yr, no lymphomas had developed in the inoculated sheep. Electron-microscopic examination of short-term cultures of phytohaemaglutinin-stimulated lymphocytes from the sheep with persistent lymphocytosis has revealed virus-like particles in five of nine animals examined but none in similar cultures from 11 uninoculated sheep. The density of particles recovered from these cultures has been determined by centrifugation on caesium chloride isopycnic density as being 1.14--1.145 gm/microliter. These particles are not typical of oncornavirus as reported from sheep and cattle elsewhere and may represent a different type of virus or indeed be non-viral.

Intracellular inhibition of human neutrophil elastase by orally active pyrrolidine-trans-lactams.

Described are the acylation binding of trans-lactam 1 to porcine pancreatic elastase, the selection of the SO2Me activating group for the lactam N which also confers metabolic stability in hamster liver microsomes, the introduction of aqueous solubility through the piperidine salt 9, the in vivo oral activity of 9 and its bioavailability, and the introduction of 9 as an intracellular neutrophil elastase inhibitor.