Sex differences in oestrogen receptor levels in adrenal glands of sheep during the breeding season

The concentrations of the oestrogen receptor (ER), and the mRNA levels of ER, progesterone receptor (PR) and insulin-like growth factor I (IGF-I) were characterised in adrenal glands and uterine tissue of adult Corriedale sheep during the breeding season. The sheep were of different sex and gonadal status. Ewes had higher levels of cytosolic ER in the adrenals than the rams (mean±S.E.M.: 7.3±2.0 fmol/mg protein and 2.5±1.0 fmol/mg protein, respectively; P=0.0091) and gonadectomy increased ER (mean±S.E.M.: 2.9±1.2 fmol/mg protein and 8.6±2.3 fmol/mg protein, intact and gonadectomised sheep, respectively; P=0.0071). No differences could be observed in mRNA levels for ER and IGF-I in the adrenal glands of all of the sheep. PR mRNA levels were reduced in ovariectomised ewes and enhanced in castrated rams (sex×gonadal status: P=0.009). PR mRNA levels tended to be higher in ewes in the follicular phase than in ovariectomised ewes and intact rams (P<0.1). All of the animals had positive nuclear staining for ER in the adrenal cortex, but no differences were observed between the groups. In this study, we demonstrated the existence of ER in the adrenal gland of sheep and found varying sensitivity to oestrogens as the ER levels differed among sex and gonadal status. These findings indicate that oestrogens most likely affect steroidogenesis directly at the adrenal cortex and suggest that oestrogens are partly responsible for the sex differences in cortisol secretion in sheep.     

Trace element supplementation of sheep: evaluation of various copper supplements and a soluble glass bullet containing copper, cobalt and selenium

The effect of 5 different copper supplements on copper status of Merino sheep at pasture was examined. Transient increases in plasma copper concentrations occurred following treatment with copper calcium EDTA, copper sulphate, and glass bullets impregnated with copper, cobalt and selenium, but these increases were not considered to be a reliable indication of changes in liver copper reserves. Sheep receiving the glass bullet or 2.5 g oxidised copper wire particles orally or 50 mg copper as copper calcium EDTA parenterally had liver copper concentrations significantly greater than those of untreated sheep for periods up to 51 weeks. Oral doses of 30 mg copper as copper oxychloride, or 300 mg copper as copper sulphate did not alter the liver copper reserves at any stage. The bodyweight and greasy fleece weights were not significantly altered by any of the copper supplements. Plasma vitamin B12 concentrations in sheep given the glass bullet were increased for about 5 months. Thereafter increased plasma vitamin B12 concentrations were observed in all sheep. Blood selenium concentrations were also high during the experiment thereby preventing the evaluation of the glass bullet as a source of selenium.     

Breed differences in sheep with respect to the accumulation of copper in the liver

Male lambs of the pure breeds Texel, Flemish milk sheep, and Finnish landrace, and of the crossbreds Texel x Friesian milk sheep, Texel x Finnish landrace, Suffolk x Friesian milk sheep, and Finnish landrace x Ile de France were fed hay and concentrates, the latter differing only in the content of copper. At high (+/- 35 ppm) and at moderately low (+/- 10 ppm) copper levels in the concentrate, breed differences in the accumulation of copper in the liver were studied. Hepatic Cu-levels increased significantly in the case of the high Cu-fed animals, but great differences in the metabolism of excessive amounts of dietary Cu exist between the particular breeds and crossbreds. The Texel breed was most susceptible to an excess of dietary Cu and the Finnish landrace was the least susceptible breed, while the Flemish milk sheep and the crossbreds were intermediate. In blood serum, the enzyme activities of sorbitol dehydrogenase, lactate dehydrogenase, gamma-glutamyl transferase, and glutamic oxaloacetic transaminase were increased to a greater or less extent in the high Cu-fed animals, but the correlation with hepatic Cu-content was poor. For the most susceptible breeds, even a level of 10 ppm Cu in a ration with nearly equal amounts of hay and concentrate is insufficiently low for the prevention of Cu-accumulation in the liver.     

The retention and efficacy of soluble-glass boluses for providing selenium, cobalt and copper to sheep

The efficacy and retention of prototype and commercial (Cosecure) soluble-glass boluses containing selenium, cobalt and copper and having a similar size, density and composition were evaluated in separate 12-month trials with sheep grazing low selenium pastures but with adequate cobalt and copper levels. In both trials, sheep confirmed by X-ray as containing a bolus grew at a significantly greater rate than control sheep. This was attributed to the correction of a selenium deficiency. Although liver copper, and liver and serum vitamin B12 levels were significantly greater in treated sheep than controls on some occasions, the differences were not as great or consistent as with blood selenium levels. The rate of bolus loss was high and in both trials, approximately 40% of the sheep had lost the bolus after 6 months. No prototype boluses were present after 12 months. Intact Cosecure boluses were recovered from 3 sheep out of 30 after 12 months whilst one animal contained a part bolus. The recovered boluses were approximately 45% lighter than when originally administered. Bolus loss did not appear to be due to complete dissolution. In sheep which had lost the bolus, blood selenium levels fell with a half-life of 43 +/- 10 days.     

Breed differences in sheep with respect to the accumulation of copper in the liver

Male lambs of the pure breeds Texel, Flemish milk sheep, and Finnish landrace, and of the crossbrech Texel x Friesian milk sheep, Texel x Finnish landrace, Suffolk x Friesian milk sheep, and Finnish landrace x He de France were fed hay and concentrates, the latter differing only in the content of copper. At high (± 35 ppm) and at moderately low (± 10 ppm) copper levels in the concentrate, breed differences in the accumulation of copper in the liver were studied‐Hepatic Cu‐levels increased significantly in the case of the high Cu‐fed animals, but great differences in the metabolism of excessive amounts of dietary Cu exist between the particular breeds and crossbreds. The Texel breed was most susceptible to an excess of dietary Cu and the Finnish landrace was the least susceptible breed, while the Flemish milk sheep and the crossbreds were intermediate. In blood serum, the enzyme activities of sorbitol dehvdrogenase, lactate dehydroge‐nase, γ‐glutamyl transferase, and glutamic oxaloacetic transaminase were increased to a greater or less extent in the high Cu‐fed animals, but the correlation with hepatic Cu‐content was poor. For the most susceptible breeds, even a level of 10 ppm Cu in a ration with nearly equal amounts of hay and concentrate is insufficiently low for the prevention of Cu‐accumulation in the liver.     

X-ray microanalysis of liver and kidney in copper loaded sheep with and without thiomolybdate administration

The distribution of elements in the cells of the liver and kidney of normal sheep, of sheep chronically intoxicated with copper and in sheep given copper and thiomolybdate was studied by atomic absorption spectrophotometry, electron microscopy and electronprobe X-ray microanalysis. Copper concentrations were increased in the liver and kidney during the pre-haemolytic and haemolytic stages of the disease. In addition iron concentrations were markedly increased in the kidney during haemolysis. Copper and molybdenum concentrations were increased in the kidney of sheep receiving copper and thiomolybdate or thiomolybdate alone. By electronprobe X-ray microanalysis at the pre-haemolytic and haemolytic stages, copper together with small amounts of calcium and chromium were found in lysosomes of liver cells. In addition, in animals killed during haemolysis, high concentrations of iron were found in apical lysosomes of kidney proximal tubule cells. Copper and molybdenum were found in apical lysosomes of kidney tubule cells in animals given copper and thiomolybdate or thiomolybdate alone. The accumulation of copper with molybdenum and sulphur in the lysosomes of thiomolybdate treated copper intoxicated animals was demonstrated for the first time and may indicate the sequestration within lysosomes of a copper-molybdenum-protein complex.     

Effect of zinc and molybdenum supplementation of the feed concentrate on the storage of copper in the liver of lambs

Summary During a 98-day trial, eight groups of eight male weanling Texel x Friesian milk sheep lambs were fed the same hay and concentrates, the latter differing only in the contents of Cu, Zn, and Mo. At high (± 30 ppm) and moderately low (± 15 ppm) copper levels in the concentrates, additions of Zn (respectively 0, 150, and 340 ppm) and Mo (0 and 16 ppm) to the concentrates were studied with regard to effect on the accumulation of copper in the liver. At the higher copper level, the addition of 150 or 340ppm Zn resulted in a significant decrease of the Cu accumulation in the liver, while at a moderately low copper level the effect of these additions on the Cu accumulation was only slight. The two Zn doses given appeared to be equally effective in reducing the Cu accumulation. Additions of zinc did not increase liver and kidney Zn. The addition of Mo. resulted in higher levels of Mo in liver and kidney. At either copper level the addition of 16 ppm Mo was more effective in reducing the Cu accumulation in the liver than the addition of 150 or 340 ppm Zn. The additions of Zn and Mo, had no visible influence on the health of the lambs. This agrees with the finding that the blood parameters (determination of haemoglobin, haematocryt, protein, copper, zinc, enzymes) and the growth of the lambs were in the normal range. These results suggest that zinc may be a useful alternative to the somewhat toxic molybdenum as an additive to concentrates for sheep in preventing Cu intoxication.     

Plasma progesterone levels in sows with induced cystic ovarian follicles.

Large multiple cystic ovarian follicles were induced in three sows and small multiple cystic ovarian follicles were induced in three other sows by injections of adrenocorticotrophic hormone (ACTH) during the follicular phase of the oestrous cycle. Plasma progesterone levels in sows with large cysts were relatively high, while those of sows with small cystic follicles were low. Removal of the ovaries with large cysts from one sow resulted in a precipitous drop in progesterone levels indicating that the large cysts were primarily the source of progesterone. The method by which ACTH may induced cystic ovaries was also investigated. Plasma progesterone levels in two ovariectomised sows during ACTH treatment fluctuated markedly during a 24 h period achieving peak values of 4 or 5 ng/ml. The results suggest that progesterone of adrenal cortical origin may be a factor in the development of the cystic ovarian condition.     

Investigations into the toxicity of Echium plantagineum in sheep: 2. Pen feeding experiments

In a pen feeding trial fresh Echium plantagineum was fed as the sole diet to crossbred sheep with or without a history of previous access to the plant. Control groups received a diet of lucerne chaff and oats. During the trial, sheep on the Echium diet lost weight and deaths occurred with histological evidence of excessive copper accumulation, usually accompanied by pyrrolizidine alkaloid damage, in the liver and biochemical evidence of liver toxicity. It is concluded that E. plantagineum alone is not a suitable fodder for sheep and can be toxic due to its pyrrolizidine alkaloid content and high copper to molybdenum ratio.     

The effects of duration and concentration of plasma progesterone on the fertility of post-partum cows treated with pregnant mare serum gonadotrophin and intravaginal progesterone

The effects of duration of insertion of progesterone releasing devices (PRIDs) on the concentrations of plasma progesterone (plasma P4) and the relationship of these with fertility were examined respectively in ovariectomised and intact Bos taurus cattle. In experiment 1, ovariectomised cows (n = 14) were treated with PRIDs to produce high and low plasma P4 for 7 or 14 days giving 4 treatment groups designated H7, H14, L7 or L14. Mean plasma P4 in the H14 and L14 groups were 6.6 and 6.0 ng/ml respectively, during the first week and 5.4 and 3.8 ng/ml respectively, during the second. Mean plasma P4 of 6.3 and 4.2 ng/ml were observed in H7 and L7. In experiment 2, suckled cows (n = 171) received the same PRID treatments as cows in experiment 1, plus either 375 or 750 iu pregnant mare serum gonadotrophin, and subsequent calving rates were recorded. These were significantly lower after L7 than the other treatments (12% v 38%, P less than 0.025). These results showed that fertility after oestrus was closely related to plasma P4 observed before oestrus and indicated that treatment with progesterone for as little as 1 week can produce normal fertility providing plasma P4 attain a critical threshold during treatment.     

Use of ammonium tetrathiomolybdate in the treatment of copper poisoning in sheep

Intravenous administration of ammonium tetrathiomolybdate (three doses on alternate days) appeared to be an effective means of containing the acute phase of copper toxicity in sheep, whether this arose from continuous ingestion of high copper feeds or by injudicious use of copper preparations for the control of copper deficiency. No adverse effects were recorded on lamb numbers, birth weight or survival of lambs born to ewes of normal to low copper status when the treatment was applied at sensitive periods of the reproductive cycle. Decreases in 'available' plasma copper and in liver damage occurred rapidly in response to intravenous tetrathiomolybdate and it is suggested that all animals at risk be treated.     

Death in sheep following dosing with copper diethylamine oxyquinoline sulphonate as a commercial injectable copper preparation

Death occurred in sheep following diethylamine oxyquinoline sulphonate (DOS) copper injections given at recommended dose rates. The copper content in unused portions of DOS copper packs was normal and free of bacterial contamination. Liver and blood copper levels in dead and sick sheep were not high. Sick sheep showed signs of hepatic encephalopathy and dead sheep were generally piled against fences and scrub. Deaths were associated with acute, severe, generalised, centrilobular, hepatocellular necrosis and live sheep had elevated circulating levels of liver enzymes consistent with liver damage. In recovered sheep there were no residual complications. It would appear that even at 0.5 mg/kg of DOS copper the safety threshold may sometimes be exceeded in some sheep.     

Copper supplementation of sheep

The effect of 6 methods of copper supplementation on copper status was examined in Merino sheep at pasture. Plasma copper concentrations were not affected by any of the treatments. Liver copper concentrations in sheep given an oral dose of 3 g of oxidised copper wire particles were significantly greater than those of untreated sheep for the duration of the experiment of 80 weeks. Subcutaneous injections of 18 mg of copper as diethylamino cupro -oxyquinoline sulphonate produced small, transient increases in liver copper. Single oral doses of 150 mg of copper as copper sulphate or 30 mg of copper as copper oxychloride produced little or no detectable increase in liver copper. Liver copper concentrations of untreated sheep were lowest in winter, apparently associated with increased damage to the abomasum, as indicated by raised plasma pepsinogen activities.     

Copper poisoning in a flock of sheep. Copper excretion patterns after treatment with molybdenum and sulfur or penicillamine

During an outbreak of chronic copper poisoning, fecal and urinary copper excretion were measured following treatment with molybdenum and sulfur supplementation of the feed (0.1 g ammonium molybdate plus 1 g sodium sulfate/sheep/day) or oral penicillamine (50 mg/kg bodyweight/day) using rams in metabolism cages. Serum glutamic-oxaloacetic transaminase activities and liver levels of molybdenum and copper in sheep that died were also monitored. Within four days of starting molybdenum and sulfur supplementation a highly significant increase in fecal copper excretion was evident and the increase persisted throughout the monitoring period (five weeks — general treatment of the flock continued for another three weeks). There was no effect of the molybdenum and sulfur supplementation on urinary excretion of copper. The molybdenum and sulfur supplementation was very effective, resulting in a rapid marked decrease in mortality. Oral penicillamine treatment induced cupruresis but did not affect fecal copper excretion. The results indicated that, while the cost of penicillamine may be a limiting factor for general treatment of a flock, it may be the drug of choice for the therapy of valuable breeding animals because cupruresis may be accurately and individually controlled. Serum glutamicoxaloacetic transaminase activities were a valuable aid in diagnosing chronic copper toxicosis as well as for monitoring recovery. High initial liver copper levels were gradually reduced following molybdenum and sulfur treatment. However, at the end of the study the liver copper levels of dead sheep varied within wide limits and there were still some sheep with high liver copper levels.     

A possible role for testosterone during luteolysis in the ewe

Increased peripheral plasma concentrations of testosterone were detected at the commencement of luteolysis and at oestrus in sheep. Daily subcutaneous administration of spironolactone (10 mg kg-1) between days 10 and 16 of the oestrous cycle suppressed testosterone secretion and delayed luteolysis and oestrus. In pregnant ewes no increases in testosterone concentrations occurred between days 10 to 16 after mating and luteal regression, monitored by peripheral progesterone concentrations, was inhibited. It is suggested that aromatisation of testosterone to oestrogens is needed for luteolysis in sheep.     

不同能量水平对羊生产性能及激素水平的影响

选用山羊和绵羊各21只,研究能量水平对羊采食量(DMI)、日增重(ADG)、饲料转化率(FCR)、胰岛素、生长激素和孕酮浓度的影响。结果表明:绵羊的DMI显著大于山羊的(P<0．05),低能量水平下,绵羊的DMI显著大于山羊的(P<0．05)。绵羊的ADG显著高于山羊的(P<0．05),高能量水平下两种羊的ADG显著高于低能量水平的(P <0．05),FCR在绵羊与山羊之间、不同能量水平之间及互作之间都不显著(P>0．05)。试验前期山羊血清胰岛素水平显著大于绵羊的(P<0．05),在低能量水平下,山羊的血清胰岛素浓度显著高于绵羊的(P<0．05)。试验前期山羊的孕酮水平显著高于绵羊的(P<0．05),高能量水平下的孕酮极显著地高于中、低能量水平下的孕酮(P<0．01),中等能量水平下,山羊的孕酮浓度显著高于绵羊的(P<0．05)。     

Effect of pregnancy and fetal development on sheep liver superoxide dismutase activity

Liver cytosolic CuZn SOD activity of four-week and 12-week pregnant sheep was twice as high as that of their fetuses and almost equal to that of control, barren ewes. By the 20th week of pregnancy activity had decreased by about 70 per cent in the maternal liver and increased to a value similar to that of the controls in the fetuses. The lysosomal CuZn SOD activity remained almost unchanged during pregnancy both in the maternal and fetal livers. Cytosolic and lysosomal CuZn SOD activities of 20-week pregnant sheep and their fetuses showed a similar electrophoretic pattern and low electrophoretic mobility. Hepatic Mn SOD activity increased sharply during fetal development but remained lower than that in both the control and maternal livers. It is proposed that the changes in CuZn SOD and Mn SOD activities are associated with changes in copper metabolism and oxygen utilisation, respectively. The low electrophoretic mobility of CuZn SOD is assumed to be a species specificity.     

Heliotropium europaeum poisoning of sheep with low liver copper concentrations and the preventive efficacy of cobalt and antimethanogen

In a field experiment in the Mallee district of Victoria, Merlno xBorder Leicester ewes and wethers grazed Heliotropium europaeum (heliotrope) over periods of 3 to 4 months in 4 successive years. By the end of the second year 12% (14 of 120) of the sheep had died; after 4 years the loss attributable to heliotrope was between 18% and 35%. Mortality was not affected by intraruminal treatment with cobalt or antimethanogen. At the end of the experiment the highest concentration of copper in the liver was 1.95 mmol/kg wet weight (approximately 413 micrograms/g dry weight). The relatively low mortality from primary heliotrope poisoning and the low concentration of copper in the liver of sheep grazing the plant are discussed in relation to the contrasting situation that prevails in the Riverina area of New South Wales. The importance of local environmental factors in the management of heliotrope grazing by sheep is emphasised, particularly in relation to the number of seasons in which the plant may be a major component of the diet.     

Sequential changes in plasma progesterone, total oestrogens and corticosteroids in cow throughout pregnancy and around parturition

Blood samples were taken thrice a week for 2 weeks from 33 pregnant cows in 9 groups, 1 month apart. In addition, blood samples were collected twice daily 1 week from 8 cows before parturition. Plasma progesterone and total oestrogens were quantified by validated radioimmunoassays and total corticosteroids by a competitive protein binding technique. During the 1st 3 month of pregnancy, no remarkable changes were observed from the 3 hormones studied. From the 4th month on, concentrations of progesterone and total corticosteroids decreased significantly (P less than 0.05) and remained fairly constant until the 9th month. Values of total oestrogens increased significantly (P less than 0.05) from the 4th to 6th months and stayed unchanged afterwards. Progesterone levels in periparturient cows decreased linearly (P less than 0.01) during 3 days preceding delivery. Concentrations of total oestrogens rose sharply from day -5 and peaked at calving. Values of total corticosteroids increased dramatically on the 6th day and 24 hours before parturition. The results obtained suggest that in contrast to studies cited earlier plasma corticosteroids could play a key role for triggering parturition in cows.     

Copper poisoning in the Kruger National Park: field investigation in wild ruminants

Chronic copper poisoning was investigated in ruminants within the Phalaborwa area of the Kruger National Park (KNP). Exposure of ruminants to environmental copper pollution resulting form copper smelting operations of a mine in the area was examined by comparing impala faecal copper concentrations in dung heaps and tissue (liver, lung and kidney) copper concentrations of organs collected from impala and buffalo culled within three risk zones (high, moderate and low) of the study area in relation to the distance from the smelter over a period of 4 years. An additional area within the KNP not exposed to the environmental copper pollution from the mine served as control. Tissue copper accumulation was also determined in tracer impala placed in the highest risk zone. The results of this study confirmed the occurrence of chronic copper poisoning in impala and indicated an inverse relationship in extent of impala faecal copper elimination and in tissue copper accumulation in impala and buffalo with distance from the copper smelter. Impala liver copper concentrations were shown to be a reliable indicator of copper accumulation for these ruminants. The presence lung copper concentrations, indicating the exposure to airborne copper were the highest in impala culled in the zone closest to the smelter. Liver copper concentrations above the diagnostic limit of 150 ppm for chronic copper poisoning in domestic sheep were consistently found in impala within the highest risk zone. Clinical pathological measurements suggested that AST activity could possibly be used as an indicator for chronic copper poisoning in impala. It is concluded that, in addition to the environmental and geo-botanical evidence previously reported, the copper smelter of a nearby copper mine is the most likely source of copper pollution responsible for chronic copper poisoning in impala and the occurrence of high copper concentrations in buffalo in the Phalaborwa area of the KNP.