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PubMed1999

The effects of urea supplementation on production and parasitological responses of sheep infected with Haemonchus contortus and Trichostrongylus colubriformis.

Merino wether lambs were individually confined and fed a basal diet of oaten chaff containing essential minerals which was untreated or contained 3% urea. Within each dietary group animals were orally infected with either 200 H. contortus (H), 1000 T. colubriformis (T) or both species (H + T) thrice weekly or remained uninfected (C). Weight gain, wool production, and parasite burden were measured over a 19-week period. Sheep on the diet containing urea gained more weight, consumed more feed and grew more wool of higher fibre diameter than their counterparts given no urea. On both diets uninfected sheep consumed more feed than infected sheep and the sheep given no urea and infected with both H and T worm species consumed the least feed. Parasitised sheep gained less weight than uninfected control sheep. Sheep with urea in their diet had lower faecal egg counts when infected with H alone or with H and T but there was no effect of urea on egg count of sheep infected with T alone. In contrast, T numbers after slaughter were reduced in sheep fed diets containing urea whereas H numbers were not affected by diet. It was concluded that supplementation with urea can increase resilience to parasitism thereby improving production and also enhance resistance mechanisms against worms in young sheep on low quality roughage diets. These responses can be partly attributed to stimulation of feed intake, presumably due to enhanced ruminal digestion, but also to elevated rumen NH3-N levels which would be expected to have increased rumen microbial protein synthesis and availability to the intestines.

Abomasum↗
PubMed1998

Dietary fat manipulation and signal transduction in ovine skin.

Protection of dietary lipids in a protein matrix prevents biohydrogenation in ruminants and increases the availability of polyunsaturated fatty acids. This alters the composition of the tissue lipids, including the membrane phospholipids, which are important substrates for signal transduction. This study investigates the effects of a diet containing protected fatty acids on the activities of key intracellular kinases in the skin. Two groups of six sheep were offered either a control diet or one containing protected cottonseed, a source of linoleic acid (C18:2), for 3 months. Skin was taken from August to October, and analysed for protein kinase C (PKC), protein kinase A (PKA), mitogen-activated protein kinase (MAPK), phosphotyrosine activity and epidermal growth factor (EGF) receptor content. Skin and wool samples were also taken to measure changes in the fibre characters and follicle function. At the end of the experiment, the mean linoleic acid content of skin phospholipids from sheep fed the protected diet was twice that of the controls. In both groups, PKC activity was significantly elevated in skin taken during September and October compared with August values. However, activities measured in the experimental sheep were higher than in controls. This coincided with a decline in wool production. PKA activity decreased significantly in both groups between August and October. MAPK activities did not alter during the experiment. Western analyses did not reveal differences in phosphotyrosine-positive or EGF receptor bands between the groups.

Animals↗
PubMed2003

Nucleation and growth of macrofibrils in trichocyte (hard-alpha) keratins.

The intermediate filaments (IF) in trichocyte (hard-alpha) keratin form ordered aggregates that are infiltrated by sulfur-rich and tyrosine-rich proteins during fiber development to give a filament-matrix texture, which is stabilized in the later stages by the formation of disulfide linkages. Two polymorphic forms of macrofibril are found in the cortical cells of fine Merino wool. In the first the packing of the IF in the macrofibril is quasi-hexagonal whilst in the second the IF are packed in cylindrical sheets around a central core. In hairs the second type generally predominate. In the present contribution specific models for the mechanisms of nucleation and growth are developed for the two types of macrofibril and their applicability tested by analyzing transmission electron micrographs of wool and hair. Evidence is presented which supports the idea that sheet formation plays an important role in both types of macrofibril assembly and it is suggested that differing intersheet interactions are responsible for the differences between the ortho- and para-types. It is shown that the increase in IF tilt with radius in the ortho-type can be related to the surface lattice of the IF as determined from X-ray diffraction studies. Two possible types of intersheet interaction in the ortho-type are discussed, the first leading to an increase of around 0.5 degrees in IF tilt per layer and the second leading to a much larger tilt of 9.4 degrees per layer. A crude estimate based on the decrease in visibility of the IF with increasing radius in cross-section yielded a value of 0.35 degrees -0.7 degrees.

Animals↗
PubMed1971

Proteins of normal hair and of cystine-deficient hair from mentally retarded siblings.

1. S-Carboxymethylkerateines extracted from normal hair can be fractionated into high-sulphur and low-sulphur proteins similar to those obtained from sheep's wool. Normal human hair gives a major high-sulphur protein of higher molecular weight and S-carboxymethylcysteine content than any isolated from normal sheep's wool. 2. The proteins from cystine-deficient hair can also be divided into high-sulphur and low-sulphur proteins. There is a lower proportion of high-sulphur protein in cystine-deficient hair than in normal hair. 3. The high-sulphur proteins from cystine-deficient hair have an abnormal amino acid composition and in particular are lower in S-carboxymethylcysteine content than the corresponding proteins from normal hair. New components are present and the content of very high-sulphur proteins of high molecular weight is much decreased. The low-sulphur proteins of cystine-deficient hair are probably also deficient in S-carboxymethylcysteine. 4. The proteins of cystine-deficient hair probably resemble those in the normal hair root, except that disulphide-bridge formation has occurred.

Acrylates↗
PubMed1980

Sulfur--selenium studies in sheep. II. Effect of a dietary sulfur deficiency on selenium and sulfur metabolism in sheep fed varying levels of selenomethionine.

The effect of a sulfur deficiency on the metabolism of selenium and sulfur was investigated in eight merino wethers. The sheep were fed high-sulfur (2 g S/kg) or low-sulfur (0.5 g S/kg) diets for two periods of 35 days each, and received selenium as selenomethionine at dietary concentrations of 0.02, 0.06, 0.09 and 0.67 mg Se/kg. Sheep fed the low-sulfur diet had reduced feed intake, reduced nitrogen, sulfur and selenium balance, but elevated plasma and wool selenium concentrations. Selenium concentrations in organs and tissues of slaughtered animals paralleled the selenium intake of the animal, with the renal cortex containing the highest concentration and bone the lowest. The effect of the 0.5 g S/kg diet on feed intake is in contrast with the results from the previous experiment (White and Somers 1977) using 0.7 g S/kg. It is this difference in fed intake which was responsible for many of the effects on selenium metabolism observed in this experiment. Once the feed intake effects are accounted for, the implications for sulfur--selenium interactions remain as before, i.e. more selenium is incorporated into wool and plasma protein when dietary sulfur is limiting than when it is not.

Animals↗
PubMed1996

Evidence for developmentally regulated transcriptional, translational and post-translational control of metallothionein gene expression in hair follicles.

The distribution of metallothionein (MT) and MT mRNAs was examined in hair (wool) follicles, where high levels of cell proliferation are found and where the resulting cells provide a temporal record of differentiation events. MT was found in the cytoplasm and some nuclei of follicle bulb cells of the proliferative zone, outer root sheath cells and in basal layer cells of sebaceous glands and sweat glands. The population of 5-bromo-2'-deoxyuridine (BrdU)+ cells in these tissues overlapped, but were not completely coincident with the distribution of MT staining. MT mRNA expression in hair (wool) follicles was assessed by in situ hybridization with four gene-specific sheep MT (sMT) isoforms. Intense signals were obtained with the sMT-Ib probe in follicle bulb cells from the proliferative zone to the keratogenous zone. Signals from the sMT-Ia probe were present in the same cells, but were much weaker. No signals were detected using the sMT-Ic and sMT-II gene-specific probes. The findings suggest that: (1) MT is important in cell proliferation and/or cell differentiation in the hair follicle bulb; (2) MT translation is inhibited during cell differentiation and migration; and (3) tissue-specific expression of uncharacterized sMT isoforms is likely.

Animals↗
PubMed1986

Clustered arrangement of keratin intermediate filament genes.

We report here that component members of the keratin intermediate filament (IF) type I and type II gene families of sheep are closely linked but apparently the two families are not. Nine genes, accounting for up to half of the keratin IF gene repertoire, were mapped in four cosmid clones and the linkage between the genes ranged from several kilobases to 20 kilobases. In one cosmid, three tandem type I genes had the same transcriptional arrangement and were regularly spaced. In another cosmid, tandem genes encoding type II keratins were identified and, surprisingly, a solitary exon was discovered in the intergene region between the two type II genes. In a normal gene this exon encodes one of the most conserved amino acid regions of IF proteins, the C-terminal end of the alpha-helical core. Homologous C-terminal protein subdomains were encoded by two wool keratin type II genes and we suggest that this arrangement may also exist in the other wool keratin type II genes.

Animals↗
PubMed1994

Effect of food intake on energy and protein metabolism in the skin of Romney sheep.

Sheep fed on either a low (500 g lucern (Medicago sativa) chaff/d; L) or high (1100 g lucerne chaff/d; H) intake had measurements made, using arterio-venous techniques, of blood flow and energy metabolite and cysteine utilization in the skin. Sheep on the H intake had significantly increased skin blood flow (P = 0.014) and oxygen uptake (P = 0.05). Although the H sheep had higher skin blood flow they showed no difference in skin uptake of either glucose or acetate compared with the L sheep, but the H sheep had a significantly lower output of lactate (P = 0.014). Animals in each group had either [14C]glucose or [14C]acetate infused into the skin which showed that acetate was the predominant precursor of skin sterol and fatty acid synthesis in the H sheep while L sheep skin used both glucose and acetate. The H sheep showed an increase in the net uptake of cysteine by the skin (P = 0.053), and in the uptake of cysteine for protein synthesis (P = 0.078), relative to the L sheep and this increase was of a comparable magnitude to the increase in blood flow to the skin. Although blood flow, protein synthesis and energy supply increased in the skin of the H sheep by 200-300%, wool production would only have increased by 10-20%, suggesting that nutrient flux changes are not the sole level of regulation of wool production.

Acetates↗
PubMed1986

Trichohyalin, an intermediate filament-associated protein of the hair follicle.

A precursor protein associated with the formation of the citrulline-containing intermediate filaments of the hair follicle has been isolated and characterized. The protein, with a molecular weight of 190,000, was isolated from sheep wool follicles and purified until it yielded a single band on a SDS polyacrylamide gel. The Mr 190,000 protein has a high content of lysine and glutamic acid/glutamine residues and is rich in arginine residues, some of which, it is postulated, undergo a side chain conversion in situ into citrulline residues. Polyclonal antibodies were raised to the purified protein, and these cross-react with similar proteins from extracts of guinea pig and human follicles and rat vibrissae inner root sheaths. Tissue immunochemical methods have localized the Mr 190,000 protein to the trichohyalin granules of the developing inner root sheath of the wool follicle. We propose that the old term trichohyalin be retained to describe this Mr 190,000 protein. Immunoelectron microscopy has located the Mr 190,000 protein to the trichohyalin granules but not to the newly synthesized filaments. This technique has revealed that trichohyalin becomes associated with the filaments at later stages of development. These results indicate a possible matrix role for trichohyalin.

Animals↗
PubMed2000

In vitro assembly and structure of trichocyte keratin intermediate filaments: a novel role for stabilization by disulfide bonding.

Intermediate filaments (IF) have been recognized as ubiquitous components of the cytoskeletons of eukaryotic cells for 25 yr. Historically, the first IF proteins to be characterized were those from wool in the 1960s, when they were defined as low sulfur keratins derived from "microfibrils." These proteins are now known as the type Ia/type IIa trichocyte keratins that constitute keratin IF of several hardened epithelial cell types. However, to date, of the entire class of >40 IF proteins, the trichocyte keratins remain the only ones for which efficient in vitro assembly remains unavailable. In this paper, we describe the assembly of expressed mouse type Ia and type IIa trichocyte keratins into IF in high yield. In cross-linking experiments, we document that the alignments of molecules within reduced trichocyte IF are the same as in type Ib/IIb cytokeratins. However, when oxidized in vitro, several intermolecular disulfide bonds form and the molecular alignments rearrange into the pattern shown earlier by x-ray diffraction analyses of intact wool. We suggest the realignments occur because the disulfide bonds confer substantially increased stability to trichocyte keratin IF. Our data suggest a novel role for disulfide bond cross linking in stabilization of these IF and the tissues containing them.

Amino Acid Sequence↗
PubMed1992

Fiber-induced hydroxyl radical formation: correlation with mesothelioma induction in rats and humans.

As part of a program to study the effects of inhaled fibers, we characterized the capacity of various fibers to initiate hydroxyl radical (.OH) formation from hydrogen peroxide in a non-cellular system. We studied five natural fibers (erionite, crocidolite, amosite, anthophyllite and chrysotile) and two man-made fibers (JM code 100 glass fibers and glass wool). The fibers were incubated for 5 min at 37 degrees C with hydrogen peroxide and salicylic acid in pH 7.0 aqueous solutions. The salicylate reacted with any .OH formed in these mixtures to produce stable addition products. The amount of .OH addition products formed during the incubations was determined by the salicylate assay which uses HPLC with electrochemical detection. Erionite, JM code 100 and glass wool were the most effective initiators of .OH formation, followed, in order, by crocidolite, amosite and chrysotile. When the capacity of the natural fibers to initiate .OH formation was plotted versus either the values for tumor rates of rats that received pleural inoculations of fibers or the literature values for the human mesothelioma mortality rates, positive correlations (r2 > or = 0.896) were found. Similar correlations with man-made fibers were not found. No positive correlation could be made between .OH formation capacity versus the tumor rates of rats that received peritoneal injections of either type of fibers.

Aluminum Silicates↗
PubMed1976

Allergy to ingredients of vehicles.

Common ingredients of vehicles such as perfumes, antibacterial agents, emulsifiers and other surface active agents, propylene glycol, lanolin and wool alcohols were tested in eczema patients over a three-year period. Perfume allergy was detected in 3.6% of the cases, sensitivity to thiomersal in 2%, to sorbic acid in 0.8%, to parabens in only 0.3%, and to wool alcohols in 1.2%. Reactions to emulsifiers were seen over 1% of those tested.

Adult↗
PubMed1999

Chamber testing of adsorption of volatile organic compounds (VOCs) on material surfaces.

A simple test chamber method to quantify adsorption and desorption of organic compounds on material surfaces is described. Important environmental parameters such as temperature, relative humidity and air velocity were varied and controlled independently around typical indoor values. Experiments were performed with alpha-pinene and toluene in concentrations of 160-300 micrograms/m3. The measurements show adsorption on and desorption from wool carpet, nylon carpet, polyvinyl chloride (PVC) floor coverings, cotton curtain material and the empty chamber. The ranking of the materials, with respect to their sorption capacity, is as mentioned above. The adsorption of alpha-pinene was higher than the adsorption of toluene for all the materials. Air velocity was not found to influence the sorption of alpha-pinene and toluene on wool carpet, tested with air velocities at 0, 10 and 20 cm/s. The experiments were carried out during both the adsorption and the desorption phase. The uncertainty of the experiments was lowest during the desorption phase. Based on the results obtained, it can be recommended that sorption experiments should be performed as desorption phase experiments. A one-sink model, based on the Langmuir adsorption isotherm, appears adequate to describe the results.

Adsorption↗
PubMed1990

The use of high-energy electrons to depilate the breech of sheep.

The use of high-energy electrons for permanently depilating areas of sheep skin was evaluated. The most effective dose of electrons for depilation was 17.5Gy. Histological changes in skin treated at this dose were examined in one sheep over 18 months and in 5 sheep over 89 d. Effects of treatment on bodyweight gains and fleece growth were examined by comparing the productivity of a further 5 sheep treated on the breech with high-energy electrons, with that of conventionally mulesed sheep (n = 5) and untreated controls (n = 5). Electron treatment resulted in immediate death of cells in the germinative region of the wool follicle bulbs. Within 10 d of treatment the treated areas were completely depilated. Wool follicle shafts in the treated areas regressed rapidly towards the epidermis and remained quiescent for the whole trial (89 d). A sheep treated 18 months previously has remained largely depilated, although a few sparse fibres are present. Epidermal acanthosis and orthokeratosis were present at 26 d after treatment. The thickened stratum corneum then sloughed off, but the epidermis remained acanthotic for the entire trial. Sweat glands and most sebaceous glands were destroyed by the treatment and were replaced by fibrotic, avascular tissue in the dermis. In all other respects the external appearance of the electron-treated breech was similar to that of mulesed sheep. There were no apparent side-effects of treatment. Neither mulesing nor electron treatment altered weight gains or fleece growth rates.

Animals↗
PubMed1992

Management of land and livestock contaminated with polychlorinated biphenyls.

Investigations were conducted on several small neighbouring beef cattle and sheep farms that were found to be contaminated with polychlorinated biphenyls (PCBs). The residues detected contained about 62% w/w chlorine and soil concentrations ranged from 0.35 to 1.9 mg/kg. Beef cattle and sheep grazing the contaminated land had PCB concentrations in their fat of 0.3 to 1.7 mg/kg and 0.19 to 0.45 mg/kg, respectively. The concentration of PCBs in the caudal fat of cattle was 0.3 to 2 times the concentration of PCBs in the land they were grazing and was positively related to stocking rates. PCBs were present in milk fat from cattle at about the same concentration as in caudal fat, and lactation appeared to contribute to decontamination. Wool grease from sheep contained about 1 to 2 times the concentration of PCBs in subcutaneous fat. Calves of contaminated cows also became contaminated. The half-life for decontamination of PCBs in a group of 8 young female beef cattle was calculated at 13 months. PCBs were detected in pasture samples at concentrations ranging from less than 0.01 mg/kg to 0.12 mg/kg. However, PCBs were not detected in any sample of hay cut from these paddocks. In 4 sheep fed a sole ration of this hay, traces of PCBs were detected in their fat following 89 days of feeding. Grazing livestock for meat production on land contaminated with PCBs is not recommended because livestock readily acquire residues, and PCBs persist in soil and livestock for long periods. Grazing sheep for wool production on land contaminated with PCBs may be an option.

Adipose Tissue↗
PubMed1999

Long-lasting prevention against blowfly strike using the insect growth regulator dicyclanil.

OBJECTIVE: To assess a ready-to-use formulation of dicyclanil to prevent blowfly strike on Merino sheep under Australian conditions. DESIGN: Randomised clinical trials conducted in an environment house and in the field. PROCEDURE: Two environment house trials were used to measure the protection against flystrike provide by a jetting or a ready-to-use 5% spray-on formulation of dicyclanil over 22 and 31 weeks respectively. Oviposition and strikes were recorded weekly for each sheep. In two field trials the occurrence of strike in Merino sheep treated off-shears or in long wool with dicyclanil or with cyromazine was compared for up to 38 weeks after treatment. Efficacy was assessed by calculating the cumulative percentage of sheep struck. RESULTS: Under environment house conditions, sheep jetted with dicyclanil at 1.50, 0.75 and 0.30 g per sheep developed 0, 8 and 9 strikes respectively during the 22 weeks of the trial, whereas there were 358 strikes present in the placebo group. Sheep sprayed with dicyclanil at 2.25, 1.50 and 0.75 g per sheep developed 5, 11 and 29 strikes respectively between weeks 15 and 31 after treatment, whereas there were 185 strikes present in the untreated controls. In field trials the cumulative percentage of sheep struck reached 1% between weeks 12 to 13 after sheep had been treated with cyromazine. Sheep treated with dicyclanil reached the 1% limit at week 21 after treatment. CONCLUSION: Under Australian field conditions, a ready-to-use 5% spray-on formulation of dicyclanil applied off-shears or to long wool protected Merino sheep from blowfly strike for a period of at least 20 weeks.

Administration, Cutaneous↗
PubMed2001

Prevention of blowfly strike on coarse and fine woolled sheep with the insect growth regulator dicyclanil.

OBJECTIVE: To assess a ready-to-use formulation of dicyclanil to prevent blowfly strike on coarse and fine woolled sheep under New Zealand conditions. DESIGN: Randomized clinical field trials. PROCEDURE: In a first field trial, coarse wooled sheep treated with a ready-to-use, 5% dicyclanil formulation were compared with untreated control sheep for up to 21 weeks. In a second field trial, fine woolled sheep, treated with the same dicyclanil formulation, were compared with untreated sheep for up to 19 weeks. Efficacy was assessed by calculating the aggregated cumulative strike rate. RESULTS: For trial 1 (coarse woolled sheep) the aggregated cumulative strike rate at the end of the trial at week 21 after treatment reached 3.9% and 19.1% for treated and untreated sheep, respectively. For the treated animals the aggregated cumulative strike rate reached the 1% and 2% benchmarks between weeks 11 and 12. For trial 2 (fine woolled sheep) the aggregated cumulative strike rate at the end of the trial at week 19 reached 0.6% and 7.5% for treated and untreated sheep, respectively. Wool length at the time of application did not substantially influence the efficacy of dicyclanil. CONCLUSION: Under New Zealand field conditions, a ready-to-use 5% spray-on formulation of dicyclanil protected coarse woolled sheep for at least 12 weeks and fine woolled sheep for at least 19 weeks.

Animals↗
PubMed1970

Potentially infectious agents associated with shearling bedpads. I. Effect of laundering with detergent-disinfectant combinations on polio and vaccinia viruses.

Glutaraldehyde-tanned woolskin pads which are used for the prevention of decubitus ulcers in bed patients were experimentally contaminated with polio or vaccinia viruses. Two methods of exposure, direct contact and aerosol, were used in separate experiments. Attempts were made to remove or inactivate these virus contaminants by laundering the woolskins in a quaternary ammonium disinfectant, a phenolic disinfectant, or alkalinized glutaraldehyde, in combination with an anionic detergent or a nonionic detergent. The effect of a commercial detergent-sanitizer was also studied. The virus titers were significantly reduced in all experiments, but only laundering in glutaraldehyde in combination with either detergent lowered the vaccinia virus titers to below detectable limits. High concentrations of glutaraldehyde altered the texture of the wool and leather apparently by precipitating a component of the detergent onto the fibers. In all the poliovirus experiments, the virus was still detectable on either or both the wool and the leather of the pads after laundering. The rinse water from each experiment was tested for the presence of virus. No vaccinia virus was recovered, but poliovirus was demonstrated in titers up to 10(3) cell culture 50% infectious doses.

Animals↗