Sequential changes in plasma methylmalonic acid and vitamin B12 in sheep eating cobalt-deficient grass.

Methylmalonic acid (MMA) concentrations are elevated in plasma as a result of vitamin B12 deficiency. This study reports the sequential changes in plasma MMA in lambs maintained on a cobalt-deficient pasture compared with supplemented controls. The results indicate that MMA is elevated in the early stages of deficiency, preceding the onset of loss of production and clinical signs of disease. It remains elevated as long as the lambs are unsupplemented with cobalt (Co). The most striking clinical sign was a loss of body condition as opposed to weight. The defect in the methylmalonyl CoA mutase is obviously an early defect in cobalt deficiency.

Studies of the transfer of dietary radiocaesium from silage to milk in dairy cows.

Four experiments were carried out to examine the transfer of radiocaesium from silage to milk by dairy cows. Three experiments assessed the effects of stage of lactation, yield and the feeding of forage only on this transfer. It was found that maximum milk radiocaesium concentrations were achieved rapidly (within 5 days) after the start of feeding contaminated silage. The transfer coefficients (Fm) were low ranging from 0.002 to 0.003 d l-1. The fourth experiment examined the effects of alternately feeding silages, of relatively high and low radiocaesium contents, on a 2 d cycle on the milk radiocaesium content. It was observed that the milk radiocaesium content changed rapidly in response to the amount of radiocaesium ingested.

Investigations of the use of clay minerals and prussian blue in reducing the transfer of dietary radiocaesium to milk.

Two experiments were performed with lactating dairy cattle to assess the efficacy of clay minerals and Prussian Blue (AFCF form) in controlling the transfer of dietary radiocaesium to milk. In Experiment 1, bentonite was included in the diet at 0, 300, 600 and 900 g d-1 and the transfer of radiocaesium from silage to milk was determined. Bentonite inclusion significantly (P less than 0.001) depressed the transfer of radiocaesium to milk with no benefit in increasing the dietary inclusion above 600 g d-1 when a 73% reduction was observed. In Experiment 2, the effectiveness of bentonite (300 g d-1), clinoptilolite (300 g d-1) and Prussian Blue (3 g d-1) as dietary additives was compared. All treatments significantly (P less than 0.001) depressed the transfer of dietary radiocaesium to milk. Clinoptilolite was less effective than bentonite and both treatments were considerably less effective than Prussian Blue, the reductions being 35%, 62% and 85% respectively.

The effects of prussian blue provided by indwelling rumen boli on the tissue retention of dietary radiocaesium by sheep.

A study was carried out to examine the effects of a form of Prussian Blue, provided by indwelling rumen boli, on the tissue retention of dietary radiocaesium by sheep. A single bolus providing 20-24 mg PB d-1 achieved a 42% reduction in tissue radiocaesium content. Multiple boli were not successful due to their loss from the rumen. The preparation used did not affect the health and well being of the animals.

Studies on the uptake, partition and retention of ionic and fallout radiocaesium by suckling and weaned lambs.

In the first part of this study 9 one week old lambs were fed, ad libitum, a liquid milk replacer diet containing 950 Bq 137Cs kg-1, for a period of 21 days. Absorption of the 137Cs from the milk replacer was over 90% during this period. The lambs were weaned onto a silage diet and then allocated to 2 groups (A and B). Group A was fed silage contaminated with fallout radiocaesium and group B with the same silage additionally contaminated with ionic 134CsCl. After a 3 week period the diets offered were changed over between the groups. During the silage feeding period the uptake of added ionic 134Cs was approximately twice that of fallout 134Cs present in the silage. These studies highlight the difficulties in using studies with the ionic form of the isotope to predict the animals' response to fallout contaminated feed.

The incorporation of Na2 75SeO3 into sheep erythrocytes.

Injection of Na2 75SeO3 into untreated, phlebotomized, and phenylhydrazine treated sheet has shown that the rate of 75SeO3-incorporation into erythrocytes is dependent on the degree of stimulation. Analysis of labeled erythrocytes by gel filtration and two-dimensional electrophoresis has indicated that the transient labeling of a hemoglobin-like peptide is the only protein labeled in addition to glutathione peroxidase.

75Selenium-labeled sheep plasma: the time course of changes in 75selenium distribution.

Sheep fed rations containing 0.1 ppm selenium were labeled by intravenous injection of radioactive sodium selenite or selenocystine. Gel filtration of serially collected plasma samples indicated that, with time, there was a transition from mercaptan sensitive to high mol wt mercaptan and protein solubilizer resistant selenoproteins. Radiolabeled plasma samples collected from selenite and selenocystine labeled sheep were dialyzed against buffer containing 2-mercaptoethanol or protein solubilizer. No difference in the stability between selenite- and selenocystine-labeled plasma could be detected.

An electrophoretic analysis of sheep plasma protein labeled with Na2 75SeO3 in vivo.

Following an intravenous injection of 75Se, sodium selenite plasma samples were analyzed by two-dimensional electrophoresis. 75Se was detected by indirect autoradiography. From 0.5 to 53 hr postinjection of 75Se, 21 75Se peptides were detected. Both the isoelectric points and molecular weights of these peptides are reported. The molecular weights of the peptides ranged from 20,000 to 70,000 daltons.

A contact dermatitis of broilers--epidemiological findings.

Lesions of a contact dermatitis have resulted in serious downgrading of broiler carcases in the Northern Ireland poultry industry. A longitudinal survey was initiated to identify the important epidemiological factors involved in the occurrence of the condition. The results from the analysis of data from 986 flocks containing 12.6 million birds over a 2 year period, have quantified the effects which the major aspects of production have on the incidence of the condition in individual flocks. The stocking density, feed manufacturer, average age of removal and the sex of birds all had a profound effect. Lesions were more frequently recorded in flocks during the winter months and a strong correlation with the weather variable, relative humidity, obtained. Individual producers and houses varied in the incidence of the condition which was closely associated with the presence of poor litter conditions in the flocks.

Lack of effect of selenium supplementation on the incidence of weak calves in dairy herds.

A double blind controlled trial was carried out on four commercial dairy herds, to investigate the effect of one 50 mg injection of selenium, 10 days before parturition, on the incidence of weak calves. Although the treatment marginally increased the selenium status of treated calves it did not decrease the incidence of the weak calf syndrome.

Characterisation of an antiserum and development of an ELISA for glutathione peroxidase.

Sheep red blood cells were fractionated by ion exchange and gel filtration chromatography to yield glutathione peroxidase approximately 99% pure. An antiserum against glutathione peroxidase was raised in the rabbit. The antiserum has been shown to cross-react with both bovine and human glutathione peroxidase by double diffusion. An enzyme linked immunosorbent assay has been developed for glutathione peroxidase which detected 6.15 X 10(-5) IU of the enzyme. The antiserum has also been shown to be effective in the detection of glutathione peroxidase immobolised on strips of nitrocellulose, subsequent to sodium dodecyl sulphate polyacrylamide gel electrophoresis, by second antibody conjugate. Avidin-biotin was also used to detect nitrocellulose immobolised enzyme. These techniques provide an alternative highly sensitive and specific means of assaying glutathione peroxidase which is not dependent on the lability of enzymatic activity nor the chemical specificity of the assay.

Use of sodium hydroxide treated selenium deficient barley to induce vitamin E and selenium deficiency in yearling cattle.

Selenium deficient barley grown in Northern Ireland was treated with sodium hydroxide to deplete it of vitamin E. Housed cattle fed a complete diet based on this treated barley developed nutritional degenerative myopathy, showing that spontaneous myopathy in yearling cattle can be the result of vitamin E and selenium deficiency alone. The diet used is as effective and cheaper than others presently in use for inducing degenerative myopathy.

Experimental 3-nitro-4-hydroxyphenylarsonic acid toxicosis in pigs.

Five times the recommended dose of 3-nitro-4-hydroxyphenylarsonic acid (187.5 mg kg-1) induces a pathognomonic clinical syndrome in pigs. The main clinical features are not continually present but are inducible only by exercise. From day 11 on the experimental diet a nervous syndrome was inducible. This manifested as muscle tremors and clonic convulsive episodes. Paraparesis developed by day 22 and paraplegia by day 33. Liver arsenic levels plateaued at 5.4 +/- 1.3 mg kg-1. The experiment confirms field observations that 3-nitro produces a characteristic toxicological syndrome, which is distinct from that of arsanilic acid. It also confirms that 3-nitro has a higher absolute toxicity than arsanilic acid in pigs as well as a lower margin of safety.

Nitrogen dioxide (silo gas) poisoning in pigs.

Toxic silo gases are a potential danger to livestock housed in close proximity to silos. On the fourth day of ensiling, five fattening pigs were found dead in a pen adjoining a grass silo. Post mortem examination revealed extensive lung damage and methaemoglobinaemia. A dense reddish-brown gas was concentrated at floor level to a height of 1 m in the pen and had diffused into adjoining pens, where dry and suckling sows and litters were showing signs of respiratory distress and weakness. The gas was identified as a mixture of nitrogen dioxide and dinitrogen tetroxide. These gases may be produced in the early stages of silage making. In this case, they had accumulated in a slurry channel below the silo and leaked through an adjoining wall into the piggery. The production and toxicological effects of silo gases are discussed.