PubMed Health⌕ Search

Biomedical subjects

N F Suttle

Publications and source records attributed to N F Suttle.

At least 37 records · Page 2Linked to original sources
PubMed1983

Effects of dietary supplements of thiomolybdates on copper and molybdenum metabolism in sheep.

When 4 groups of 3 lambs were reared on a milk substitute containing 10.5 mg of Cu per kg DM with or without supplements of Cu, 5 mg, and Mo, 3 mg per kg DM in a 2 X 2 factorial design, Mo, given as ammonium tetrathiomolybdate (MoS4) reduced hepatic Cu retention by one-third but had no effect on the amount or distribution of Cu in plasma or on plasma Mo concentrations. When 2 groups of 5 lambs were weaned on to a cereal-based diet containing 3.5 mg Cu per kg DM and one was given MoS4 in the amount used previously, concentrations of Mo and TCA-insoluble Cu in plasma and the rate of depletion of liver Cu were increased. When Cu, 12 mg per kg DM, was finally added to both diets the plasma changes were reversed but the hepatic retention of Cu was still reduced. In a second experiment, 6 groups of 5 hypocupraemic ewes were repleted with a dietary Cu supplement in the presence of one of 3 Mo sources, molybdate (MoO4), dithiomolybdate (MoO2S2) or tetrathiomolybdate (MoS4) providing 3.0 mg Mo per kg DM each in the presence of low or high dietary S. The effects of the S supplement were dominant, causing the MoO4 and MoO2S2 to behave like MoS4 in impairing Cu and Mo absorption and inducing TCA-insoluble Mo and Cu to accumulate in the plasma: S enhanced these responses to MoS4 even further. On the low S diet, the responses to MoO4 and MoO2S2 were similar but small. It is concluded that at high dietary Mo and S concentrations, sufficient MoS4 forms in the rumen and enters complexes with Cu to impair Cu absorption but that the formation of MoO2S2 does not play an important role in the Cu and Mo antagonism.

Absorption↗
PubMed1983

The effect of copper deficiency on the resistance of mice to infection with Pasteurella haemolytica.

Mice adjudged copper deficient on the basis of significantly decreased blood and tissue copper content and superoxide dismutase activity, but generally showing no clinical signs of deficiency, were infected intraperitoneally with Pasteurella haemolytica. In 3 separate experiments the LD50 for deficient animals was significantly depressed below that of copper-sufficient controls. Furthermore, in mice surviving challenge at doses near to the LD50, spleen weights were significantly increased and body temperatures depressed in the copper-deficient animals. These results indicate that subclinical copper deficiency in the mouse, is associated with an increased susceptibility to experimental infections with P. haemolytica.

Animals↗
PubMed1983

Use of erythrocyte copper:zinc superoxide dismutase activity and hair or fleece copper concentrations in the diagnosis of hypocuprosis in ruminants.

Changes in the activity of superoxide dismutase, a copper-containing enzyme in erythrocytes (ESOD), and changes in copper in hair or fleece were compared with the changes in plasma copper during copper depletion and repletion in steers, lambs and ewes. During depletion the decline in ESOD began later than the decline in plasma copper: the lag varied from 0 to 80 days in individual steers and it was least evident when young rapidly growing lambs were subjected to severe depletion. ESOD activity eventually declined at only one-third to one-seventh of the rate shown by plasma copper, the difference being particularly marked in severely depleted lambs. Repletion of ESOD began after repletion in plasma copper and continued more slowly particularly in growing animals. Hair and fleece copper also responded relatively slowly to depletion and repletion. Low values of ESOD and hair or fleece copper may have diagnostic significance, indicating a more prolonged or intense deficiency of copper and a higher probability of clinical and production responses to copper therapy than low plasma or liver copper values.

Animals↗
PubMed1982

A model for zinc metabolism in sheep given a diet of hay.

1. Four pairs of Scottish Blackface ewes were given a basal diet of hay, providing 8 mg zinc/d, and one of four levels of supplementary Zn (0,75, 150 or 225 mg/d) continuously by intraruminal infusion. 2. 65Zn (59 microCi) was given intravenously after stabilization for 14 d and the changes in specific radioactivity (SR) of plasma and faeces were monitored for a further 10 and 13 d respectively. The faecal endogenous losses and absorption of Zn were estimated, using the principle of isotope dilution, by two methods using the whole or latter parts of SR:time curves. 3. Faecal endogenous losses were estimated by the part area method to be 4.9, 6.4, 5.1 and 6.3 +/- 0.35 mg/d at 0, 75, 150 and 225 mg supplemental Zn/d i.e. largely unaffected by Zn intake and averaging 0.11 mg/kg live weight (LW). The whole area method gave similar results. 4. Urinary excretion was negligible (probably less than 0.2 mg/d) for all sheep. 5. The amount of Zn absorbed was assumed to equal the irreversible loss of Zn under steady-state conditions and found to remain constant at 7.6 +/- 0.39 and 10.3 +/- 0.6 mg/d when calculated by "whole' and "part area' methods. Zn retention did not increase with Zn intake and homoeostasis was achieved primarily by control of Zn absorption which fell from 0.75 to 0.03 or from 0.96 to 0.05 of intake, depending on method of calculation, as intakes increased.

Animal Feed↗
PubMed1981

Comparison between parenterally administered copper complexes of their ability to alleviate hypocupraemia in sheep and cattle.

In a comparison of four parenteral copper preparations for sheep administered at similar dose rates, copper as diethylamine oxyquinoline sulphonate (copper DOS) was found to alleviate hypocupraemia in ewes more consistently than copper calcium EDTA and copper-methionate, given in a cream (C) or aqueous base (A). In similar comparisons of preparations for cattle, copper calcium EDTA was 19 per cent more effective than copper DOS and 36 to 48 per cent more effective than copper methionate (A). Methionate preparations were characterised by marked reactions at and slow translocation from the site of injection whereas copper DOS was rapidly translocated and gave little or no tissue reaction in sheep or cattle. Attributes of an improved parenteral copper preparation are discussed in the light of disadvantages of existing preparations.

Animals↗
PubMed1981

Effectiveness of orally administered cupric oxide needles in alleviating hypocupraemia in sheep and cattle.

The oral administration of a small dose of cupric oxide "needles" (CuOn), providing 0.5 g copper, to hypocupraemic ewes maintained on a copper-deficient diet alleviated hypocupraemia for 111 days when the diet was supplemented with molybdenum and sulphate and for 301 days when the diet was not supplemented. The same amount of copper given as cupric sulphate was approximately half as effective. The administration of a large dose of CuOn, providing 40 g copper, to hypocupraemic steers and heifers alleviated hypocupraemia for not less than 41 days, at which time a substantial reserve of copper (428 mg) remained in the liver. The absorbability of copper in CuOn was estimated to be 8.3 per cent and 3.8 per cent (depending on diet) for sheep. It was calculated that enough absorbable copper could be provided in a single dose to meet the net copper requirements of ewes for several years. This new form of copper therapy demands a totally different approach from that associated with parenteral copper usage.

Animals↗
PubMed1981

Some effects of copper deficiency on leucocyte function in sheep and cattle.

Peripheral blood leucocytes from copper-deficient (less than 8 mumol per litre plasma) and copper-sufficient (more than 8 mumol per litre) ewes and lambs were tested for their ability to ingest and kill Candida albicans in vitro. Killing capacity was significantly reduced in both copper-deficient ewes and lambs, although phagocytic capacity was apparently unimpaired. Similar results were obtained with copper-deficient calves, in which it was further shown that copper repletion restored candidacidal activity. Leucocyte and erythrocyte superoxide dismutase (LSOD and ESOD respectively) activities were both significantly decreased in hypocupraemic ewes and there was a linear relationship between their activities in the two cell types: LSOD activities were reduced by approximately 35 per cent and ESOD activities by 67 per cent. Cyanide inhibition tests indicated that the manganese-dependent form of the enzyme contributed little to the total activity of LSOD or ESOD. There was a tendency for leucocytes from copper-deficient ewes to release greater amounts of superoxide anion after stimulation with opsonised zymosan. Their viability was similar to that of leucocytes from control sheep and was unaffected for up to three hours after stimulation.

Animals↗
PubMed1980

Some problems in assessing the physiological and economic significance of hypocupraemia in beef suckler herds.

Factors influencing the incidence of hypocupraemia and responses to copper therapy were investigated in three beef suckler herds calving in spring and early summer. On farm A hypocupraemia was most severe (plasma copper less than 0.4 mg per litre) in March for the cows and in October/November for their calves. On farm B plasma copper levels were 30 per cent lower in five to eight-year-old cows than in two-year-old cows in late November. Administration of copper (100 mg) in late pregnancy significantly increased plasma copper in the suckled calves on farm A but not in their dams after parturition. Growth of the calves was not increased. The alleviation of severe hypocupraemia on a third farm (C) by injecting the calf with copper did not improve growth rate. It is concluded that in some areas a severe seasonal hypocupraemia may be tolerated without loss of productivity.

Animal Feed↗
PubMed1979

Some effects of sulphur intake on molybdenum metabolism in sheep.

1. To investigate the effects of sulphur intake on molybdenum metabolism in sheep, ewes were given intakes of 0.3 or 3.5 mg Mo and 0.98, 1.33, 1.73 or 3.23 g S/d in a 2x4 factorial experiment with two replicates lasting 35 d. 99Mo with 0.1 mg carrier Mo was infused intravenously for the last 14 d and, when 99Mo concentrations in urine and faeces had attained plateaux (days 11-14), stable Mo and 99Mo balance trails were conducted; samples of blood and rumen contents were taken principally for studies of Mo distribution. 2. Increases in S intake caused the following changes in Mo metabolism; absorption decreased, urinary and faecal endogenous excretion decreased and retention increased; Mo concentrations in rumen contents decreased but the predominant association with the solid phase was unaffected; Mo concentrations in plasma decreased, but a higher proportion was associated with the protein fraction; Mo in protein-free plasma became apparently less ultrafiltrable at the glomerulus. 3. The pattern of response to S for each factor was generally curvilinear, the first increment in S intake having by far the greatest effect. The effect of S was generally greatest at the higher Mo intake. 4. It is suggested that the manifold effects of S on Mo metabolism are related to a common interaction in the rumen leading to the formation of Mo-complexes, possibly thiomolybdates, which are poorly absorbed but even more poorly excreted.

Animals↗