There is widespread recognition that small increments in herbage molybdenum (Mo) concentrations can induce hypocuprosis and a recent study indicated that preventative measures might also be affected: copper oxide needles afforded less protection to ewes on high Mo diets than those on low Mo diets (Suttle, 1981 a). The effect of dietary Mo on the ability of other oral and parenteral copper (Cu) sources to alleviate hypocupraemia was therefore examined. Groups of Blackface ewes were depleted for each experiment by feeding a semi-purified diet containing 1 — 1.3mg Cu/kg DM and 4 g sulphur (S)/kg DM. Molybdenum was added as Na2Mo04, to provide an additional 4 mg Mo/kg DM to the 0.5 — 0.8 mg/kg DM present in the basal diet.

The work of Dewey (1977), in Australia, showed that the oral administration of cupric oxide wire (CuON), in lengths of between 5-10 mm and a mean diameter of 0.5 mm, at a dosage rate of 10 g in a gelatin capsule to mature sheep, produced a steady increase in liver copper (Cu) concentrations over 16 days to levels over 1000 mg/kg DM above the initial levels. The 'needles' lodged primarily between the abomasal folds and, by 64 days, were no longer detectable. In grazing conditions, a dose of 20 g was administered to sheep. At neither dosage level were deleterious effects noted. Suttle (1981) administered 0.5 g CuON to hypocupraemic ewes maintained on a Cu-deficient diet and alleviated hypocupraemia for 111 days when the diet was supplemented with molybdenum (Mo) and sulphur (S), and 301 days when the diet was not so supplemented.

A satisfactory method of copper (Cu) supplementation, particularly in the field situation, has yet to be found (MacPherson, 1983). Work in Australia (Dewey, 1977 and Deland, Cunningham, Milne and Dewey, 1979) has shown that orally administered copper oxide wire or ‘needles’ (CuON) remained in the lining of the abomasum of sheep and calves and gradually released Cu over a long period of time. This treatment was successfully tested on hill sheep in Scotland by Whitelaw, Armstrong, Evans, Fawcett, Russel and Suttle (1980). Suttle (1979) has also recorded that calf liver Cu concentrations were raised significantly by a single 50 g oral dose in a limited term (41 day) experiment. No reports have appeared of the usefulness of this treatment under field conditions for the bovine in this country. Three trials are described which examined the effectiveness of small oral doses of CuON on the Cu status of beef suckling calves, dairy heifers and beef suckler cows.

A field trial was carried out to test the efficacy of proprietary copper (Cu) tabletst in preventing hypocupraemia in beef cattle grazing molybdenum (Mo)-rich pastures. This product is based on a specially formulated matrix, which is claimed to control the solubility product of inorganic metallic salts when the tablets are suspended in a plastic container in water troughs.

The prevention or treatment of trace element deficiencies in grazing livestock can be both expensive and inconvenient. As an alternative to the customary parenteral administration of copper (Cu) or the use of cobalt (Co) bullets, we have investigated the feasibility of treating animals by supplementation of their drinking water with Cu or Co, using the Rowett Water Proportioning Device (Patent No. 16784/78).

The interpretation of serum vitamin B12 concentrations in cattle is not well established but a value <350 ng/1 is commonly used to describe adequacy (MAFF, 1978). Three separate experiments explore this interpretation and the ability of cobalt (Co) bullets to increase serum vitamin B12 concentrations in cattle. In all cases, vitamin B12 has been measured microbiologically, using the organism L. leichmannii. In experiment 3, a number of samples were additionally analyzed using a radio isotope dilution (RID) technique.

The high level of cobalt (Co) in soil relative to herbage means that soil accidentally ingested with herbage may constitute the larger source of the element for vitamin B12 synthesis by rumen microbes.

A continuous culture simulation of rumen fermentation (Rusitec: Czerkawski and Breckenridge. 1977) was used to determine the extent to which soil Co was used for microbial vitamin B12 synthesis. A low Co hay (0.044 mg/kg DM), 7.25 g DM/day, was “fed” to each of four vessels for a period of 8 days to provide resting values for vitamin production. A chalk, a sand, a clay or a loam, with Co concentrations ranging from 0.70 to 64.5 mg/kg DM (see Table 6.15.1), were then added at 0.70 g/day, to the hay in separate vessels each morning for 14 days. For a further period of 10 days, the hay in two vessels was supplemented with either chalk or loam at 1.4 g/day. Daily vitamin B12 production was measured by analysis of each vessel's effluent for cobalamin (cbl.), using a modification of the method of Green (1980). Vitamin B12 analogue production was assessed from the Lactobacillus leichmannii microbial assay of the effluent. All vessels produced a “roughage” fermentation (acetate c. 50% and propionate c. 20% of the total volatile fatty acids) with the soil supplements.

The clinical signs of copper (Cu) deficiency are largely non-specific and a number of laboratory tests have been used extensively to assist in diagnosis. Among these are whole blood, plasma and serum Cu and caeruloplasmin (McMurray, 1980). However, for any marker to be useful diagnostically, it is necessary to identify any factors which can affect it. Plasma and serum Cu are not equivalent but are related by the equation:

Serum Cu (mg/l) = 11.7 + 0.66 plasma Cu (mg/l). The regression was obtained from the means of 24 groups of suckler cows and calves (> 10 animals/group). The equivalent relationship between serum and plasma caeruloplasmin is:

Serum caeruloplasmin = 0.0018

+ 0.59 plasma caeruloplasmin.

Units of caeruloplasmin are absorbance units in the phenylene diamine assay.

Thus, the range of normality will depend on the sample being used for the assay. The reduction in serum values is due to the loss of caeruloplasmin during blood clotting.

Chronic copper (Cu) poisoning is a well recognized problem in sheep and there is evidence that the incidence is increasing as more intensive methods of production are adopted. The interaction between Cu, molybdenum (Mo) and sulphur (S) in ruminants is well known and diets supplemented by Mo and S have been used to reduce the incidence of Cu toxicity in sheep. It has been postulated that Mo reacts with sulphide in the rumen to form thiomolybdate (TM) and that this subsequently combines with dietary and/or tissue Cu to form complexes in which Cu is unavailable to the animal. We have evaluated the response of Cu-dosed sheep to the intravenous administration of TM.

The liver is important in the homeostatic regulation of manganese (Mn) and copper (Cu). The rates at which the liver removes these trace elements from plasma and excretes them in bile have been measured by using either cattle in which the duodenum had been surgically modified to allow bile to be sampled and its rate of flow measured, or cattle with cannulae in hepatic, portal, mesenteric and carotid vessels.

Piglets rapidly become anaemic after birth because the sow's milk provides only about 10% of their iron (Fe) requirements. Under free-range conditions, they can obtain extra Fe from soil but in modern intensive systems no soil is available and to prevent them becoming anaemic the piglets are injected with 200 mg Fe as iron dextran when 2-4 days of age. These injections are effective but they are costly in time and money and can have undesirable side effects such as the formation of abscesses, staining of the injected ham or even death from Fe toxicosis. We have considered the theoretical and practical possibilities of supplying the piglets with Fe by using their dams' faeces as a substitute for soil.