Accidental contamination of the public water supply at Lowermoor, Camelford: an assessment of the possible veterinary consequences.

As a result of the delivery of 20 tons of concentrated aluminum sulphate solution into the wrong part of the Lowermoor water treatment works the water supplies of 20,000 people and many thousands of cows, sheep, pigs and poultry became contaminated with aluminium, copper, zinc and lead. When the water mains were flushed into the rivers Allen and Camel many fish were killed by the high concentrations of aluminium. However, there appear to have been no detrimental effects on farm live-stock; this was either because the animals were likely to have ingested less of the toxic elements from the water than they ingest with normal components of their diet, including soil, or because the abnormally high intakes lasted for only a short time.

An assessment of the risks to the health of grazing animals from the radioactive contamination of pastures.

As a result of the Chernobyl accident sheep and cattle in Wales, Cumbria and Scotland became contaminated with radionuclides of caesium and iodine. In the worst case, the maximum levels of contamination were of the order of 4000 Bq/kg of caesium-137 and 2000 Bq/kg of caesium-134 in muscle and 2,000,000 Bq/kg of iodine-131 in the thyroid gland. Calculations show that the radiation dose rates to the animals from these burdens of the radionuclides of caesium would have been approximately one thousandth of the dose rate needed to cause clinical signs of damage; in the case of iodine-131 approximately 10,000 times higher levels of the nuclide would have been required to cause clinically perceptible damage to the thyroid gland. In any forseeable nuclear accident severe problems of human health would arise before any detrimental effects on livestock could be detected.

The development of acid-base reaction cements as formulations for the controlled release of trace elements.

Novel acid-base reaction cements have been developed for use as controlled release formulations. Many new ones have been discovered and assessed; these include those which are capable of releasing copper, cobalt or selenium singly or in combination. A selection was made of the most suitable formulations for this purpose and these were subjected to field trials.

Reaction cements as materials for the sustained release of trace elements into the digestive tract of cattle and sheep. I. Copper release.

Acid-base reaction cements were produced by reacting copper oxide with phosphoric acid. When placed in the reticulo-rumen of cattle and sheep these cements released copper into the digestive tract for at least 3 months at a rate sufficient to provide the animals' requirements for copper. Lambs given a pellet of cement at 3 months of age had significantly greater concentrations of copper in their livers than similar untreated animals when slaughtered 3-4 months later. It was shown that salts of cobalt and selenium could be incorporated into the cement to provide additional supplementation with these two elements.

Barium selenate injections in cattle: effects on selenium concentrations in plasma and liver and residues at site of injection.

Twenty Angus cross heifers were fed a complete diet which contained 0.07 mg selenium/kg dry matter. Thirteen were injected subcutaneously with barium selenate at a dose rate of approximately 1 mg selenium/kg bodyweight and seven remained untreated. All the heifers were slaughtered during the following 121 days, the last of the treated group 119 days after injection. Glutathione peroxidase activity in blood increased within four weeks of administration and remained high thereafter. The selenium dependent glutathione peroxidase activity did not increase in liver kidney or muscle. The concentrations of selenium in the blood, liver and muscle were increased significantly from 30 days until 119 days. Between 76 and 99 per cent of the selenium injected remained at the site of injection.

Vitamin B12 absorption in the neonatal piglet. 1. Studies in vivo on the influence of the vitamin B12-binding protein from sows' milk on the absorption of vitamin B12 and related compounds.

The vitamin B12 in sows' milk is strongly attached to a specific 'binder' protein, which is present in excess. The influence of this 'binder' on the uptake and retention of cyanocobalamin and two natural analogues (cobinamide and Co-alpha-[2-methyladenyl]cobamide) was investigated with neonatal piglets. Retention of a single oral dose of cyano[58Co]cobalamin given before 7 d of age was consistently higher with suckled than with early-weaned piglets, as determined by measurement of whole-body radioactivity. Efficiency of retention declined with age, more rapidly in early-weaned than in suckled animals; when the dose was given at 14 d approximately 30% was retained by both groups. Distribution of the retained cyano[58Co]cobalamin within the body of the piglets was the same in both groups; about half was present in the liver. Foraging piglets may ingest adventitious vitamin B12 and its analogues, which are present in the sow's faeces and in contaminated litter. The influence of the vitamin B12-binder in sows' milk on the uptake and retention of two non-cobalamin analogues, and the effects of the analogues on the uptake and retention of vitamin B12 from 2 to 14 d after parturition, were investigated with early-weaned piglets. The analogues were detected in the liver but not in the body organs. They were also present in blood plasma, urine and bile, in high concentration relative to that of vitamin B12. The content of analogues in the liver was very small in relation to the amounts ingested, and much less than that of vitamin B12. There was no indication that the vitamin B12-binder in sows' milk influenced uptake and retention of the analogues, or that ingestion of analogues affected the content of vitamin B12 in the body organs and fluids examined.

Boluses of controlled release glass for supplementing ruminants with cobalt.

Boluses of controlled release glass containing cobalt and weighing approximately either 60 g or 14.5 g were administered to 22 steers and 21 sheep respectively. The steers were housed and slaughtered at intervals between 17 and 145 days after dosing. The boluses released more than 0.85 mg cobalt daily. In both untreated and dosed animals serum and liver vitamin B12 concentrations were at the upper end of the normal range. Two types of glass were administered to sheep. In five wethers one glass released 0.07 mg cobalt per day, and in 16 grazing lambs a second glass released more than 0.15 mg cobalt per day. Fourteen of the boluses were recovered from the lambs up to 276 days after dosing. The concentration of B12 in serum of lambs increased significantly from a mean +/- sd of 1.64 +/- 0.47 to 2.02 +/- 0.04 ng/ml serum and the concentration in liver from 3.84 +/- 0.85 to 4.99 +/- 0.72 micrograms/g dry weight liver.

Importance of water for the health and productivity of the dairy cow.

Four lactating Friesian cows (average weight 485 kg, milk yield 22 kg d-1) were maintained in completely controlled circumstances and deprived of water for 72 hours. During this period they were carefully monitored and lost 100 kg in bodyweight, principally accounted for by cumulative losses of water in milk, urine, faeces and respired air. The mean rates of respiration and rumen contraction decreased by approximately 50 per cent. Mean body temperature increased by 0.5 degrees C, but pulse rate did not change significantly. Dry matter intake, particularly of hay, decreased rapidly to less than 10 per cent of normal on the third day. Milk yield decreased only slightly during the first 24 hours but on the third day the average yield was only 28 per cent of normal; the composition of the milk did not change significantly. There were significant progressive increases in serum sodium concentration (after four hours water deprivation), osmolality (after 24 hours), urea (after 38 hours), copper (after 48 hours) and magnesium and total protein concentration (after 62 hours); packed cell volume (measured with a Coulter Counter) increased after 38 hours but packed cell volume (determined in a microhaematocrit centrifuge) increased only after 62 hours. In spite of the dehydration the cows showed no signs of distress. Within 48 hours of the cows being given free access to water, bodyweight, appetite, milk yield and blood composition had returned almost completely to normal.

Boluses of controlled release glass for supplementing ruminants with copper.

A controlled release glass was formulated into boluses weighing approximately 17 g or 75 g and administered to 19 lambs and 20 steers respectively. The animals were at pasture during the summer months. The lambs were slaughtered between 57 and 219 days after dosing when the mean concentration of copper in their livers had increased to 107.8 +/- 33.4 mg copper/kg fresh weight compared with 55.9 +/- 23.0 mg copper/kg fresh weight in undosed controls. The steers were slaughtered more than 140 days after dosing; the mean concentrations of copper in plasma had increased and the mean concentration of copper in liver was significantly greater than in undosed control steers (14.1 +/- 4.8 mg copper/kg fresh weight liver in dosed steers, 4.7 +/- 1.4 mg copper/kg in control steers) and was similar to the concentration in steers which had received 200 mg copper as copper calcium edetate (18.2 +/- 4.2 mg copper/kg fresh weight). In sheep the minimum rate of release of copper into the reticulorumen was 2.1 mg/day and in steers 11 mg/day.

The absorption of anabolic agents from pellets implanted at the base of the ear in sheep.

Twenty wether sheep were allocated to seven groups and received implants near the base of one ear with pellets containing: for group 1, (OE) 20 mg oestradiol-17 beta alone; for group 2, (TBA/OE) 20 mg oestradiol-17 beta intimately mixed with 140 mg trenbolone acetate; for group 3, (T/OE) 20 mg oestradiol-17 beta mixed with 200 mg testosterone; for group 4, (P/OE) 20 mg oestradiol-17 beta mixed with 200 mg progesterone; for group 5, (TBA/OE2) 20 mg oestradiol-17 beta in one ear and 140 mg trenbolone in the other ear; for group 6, (TBA/OE1) 20 mg oestradiol-17 beta and 140 mg trenbolone as separate pellets in one ear; group 7 sheep received implants of carrier material and served as controls. The concentrations of steroids were measured in plasma samples collected from both jugular veins during the 16-week period after implantation. The absorption of oestradiol-17 beta was slower and more sustained from the pellets in which it was mixed with other steroids (groups 2, 3 and 4) than from the pellets containing oestradiol-17 beta alone (groups 1, 5 and 6). The concentration of each steroid in plasma was higher in the jugular vein ipsilateral to the implant than in the vein on the opposite side. The difference between the concentrations in the two veins was used to calculate the biological half-lives of the steroids; for oestradiol-17 beta and trenbolone the mean values ranged from 1.8 to 6.8 min and from 3 to 4 min, respectively, and for testosterone and progesterone the mean values were 4.7 and 3.5 min, respectively.

Effects of selenium and copper supplementation on the growth of beef steers.

During the grazing seasons of 1978 and 1979, 126 Hereford cross Friesian and 25 Charolais cross Friesian steers were used in controlled trials of the effects of injecting them with copper and, or, selenium. In both seasons the unsupplemented steers had low blood concentrations of copper, selenium and glutathione peroxidase, whereas the supplemented steers maintained their serum copper concentrations within the normal range and had significantly higher whole blood concentrations of selenium and glutathione peroxidase than the unsupplemented animals. Supplementing the steers with 400 mg copper during 1978 increased their growth rate by 0.032 kg/day and supplementing them with 200 mg copper during 1979 increased it by 0.080 kg/day. Supplementing the steers in each year with two doses of selenium, each of 0.15 mg selenium/kg bodyweight, increased their growth rate by 0.041 kg/day in 1978 and by 0.060 kg/day in 1979. There was no interaction between the selenium and copper treatments and the total increases in liveweight gains due to both supplements were around 11 kg in 1978 and 16 kg in 1979.

Magnesium and milk fever.

There is clinical, experimental and theoretical evidence for a connection between the occurrence of subclinical hypomagnesaemia and the incidence of milk fever. Clinically, pregnant dry cows in dairy herds with a high incidence of milk fever have often been observed to have subnormal blood magnesium concentrations. Experimentally, it has recently been shown that subclinical hypomagnesaemia reduced the ability of cows to mobilise calcium in response to hypocalcaemia; a response which is essential if cows are to avoid milk fever. And theoretically there are several points in the biochemical pathways for calcium where a need for magnesium has been demonstrated in laboratory rodents. These connections between subclinical hypomagnesaemia and milk fever are explored and their consequences for the prevention of milk fever are considered.

Calcium mobilisation in hypomagnesaemic cattle.

Intravenous infusions of EDTA solution (4.7 per cent w/v) were used to induce hypocalcaemia in six steers and six non-pregnant lactating Friesian cows, once when they were normomagnesaemic and once when they were hypomagnesaemic (less than 0.85 mmol Mg per litre) and their rates of calcium mobilisation have been measured. The mean rates of calcium mobilisation by the normo- and hypomagnesaemic steers were 0.32 mmol/min and 0.21 mmol/min respectively (P less than 0.005) and the mean calcium mobilisation rates of the cows were 0.41 mmol/min and 0.26 mmol/min respectively (P less than 0.02). It is concluded that hypomagnesaemia reduced the calcium mobilisation rate in both steers and non-pregnant lactating cows.

Virulence of Bordetella bronchiseptica from pigs with or without atrophic rhinitis.

The virulence of 17 isolates of Bordetella bronchiseptica from 13 pig herds was compared by intranasal infection of gnotobiotic piglets and LD50 tests on mice. Of 59 piglets given 8.1-10-5 log 10 colony-forming units (cfu) of isolates from two herds with atrophic rhinitis (AR isolates) or isolates from six unaffected herds (non-AR isolates), 16 died of acute pneumonia; the survivors developed non-progressive turbinate hypoplasia and chronic pneumonia. Infection of 11 piglets with c. 3.0 log to cfu of three AR isolates or three non-AR isolates caused turbinate hypoplasia, but only slight pneumonia and no deaths. There were no significant differences between the virulence of AR and non-AR isolates in piglets. In LD50 tests in mice, there were no significant differences between the results from six AR isolates and six non-AR isolates, or from toxin prepared from two AR isolates and one non-AR isolates was fairly uniform, and that other factors must be responsible for the occurrence of progressive lesions of atrophic rhinitis in some but not all infected herds.