Evaluation of controlled-release devices for providing chromium sesquioxide and zinc in Huacaya alpacas at pasture.

OBJECTIVE: To assess the effectiveness of controlled-release devices (CRDs) for providing zinc and for estimating faecal output in alpacas and sheep at pasture. METHODS: The study groups of 10 alpacas and 10 sheep at pasture were paired within species and allocated at random to receive by mouth either one CRD containing chromium sesquioxide designed to function for at least 21 days or two CRDs, one containing chromium sesquioxide and the other zinc oxide designed to release over a nominal 60-day period. Faecal concentrations of chromium, zinc and ash, blood and plasma concentrations of zinc and plasma activity of alkaline phosphatase (ALP) were measured over a period of 117 days after treatment. RESULTS: The mean faecal chromium excretion profiles suggested that the CRDs performed in a similar manner in both species, releasing chromium for nearly 30 days in alpacas and for slightly more than 30 days in sheep. Using a common predetermined release rate of chromium from the CRDs, the daily faecal outputs of alpacas and sheep were estimated to be 0.54 kg dry matter and 0.33 kg dry matter, respectively. The CRD containing zinc oxide provided after 1 week an estimated daily release rate of 40 mg zinc with a lifetime of between 60 and 70 days in both species. The additional zinc did not elicit a response in blood zinc concentrations or in plasma ALP activity. CONCLUSION: The CRDs were retained in the gastrointestinal tracts of the alpacas and sheep and both types functioned as expected. The CRD delivering chromium sesquioxide at a known release rate provided an estimate of faecal dry matter output over a period of almost 3 weeks and the CRD formulated to deliver supplementary zinc did so at the nominal release rate over a period of approximately 60 days in both species. These data indicated that the standard sheep CRD is applicable for use in alpacas.

Depot injection of barium selenate for long-term prevention of selenium inadequacy in beef cattle.

In southern Australia, cattle at risk from selenium (Se) deficiency can be given an oral dose of supplements that are effective in maintaining adequate Se status for between 9 and 12 months. The present study was undertaken to assess the duration of the effect of parenteral barium selenate (BaSe) in raising the Se status of cattle at pasture in an area of marginal Se deficiency. The BaSe was given subcutaneously to Hereford heifers, using an 18-gauge needle. Cattle had regular blood sampling to assay Se, from 8 days before dosing to 1155 days afterwards. Results show that a single injection of BaSe was effective in elevating blood and plasma Se concentrations to normal values for at least 2 to 3 years, when given to beef cattle of low normal Se status. We suggest that a prophylactic dosage of 0.5 mg Se/kg body weight as BaSe should be given every 2 years to prevent Se inadequacy in beef cattle grazing pasture of marginal Se content.

Factors associated with low vitamin D status of Australian alpacas.

OBJECTIVE: To investigate factors associated with low vitamin D status of alpacas at pasture in southern Australia. DESIGN: A 2-year survey of alpacas from two farms in South Australia and three in Victoria. Blood samples were collected from 20 to 30 alpacas on each farm on five occasions each year. Breed, gender, age and fleece colour of animals were recorded. METHOD: Blood samples were assayed for plasma 2.5-hydroxycholecalciferol (25-OH D(3)) and plasma inorganic phosphorus (Pi). Data sets from 802 animal samples were analysed by multiple regression to determine variables associated with low vitamin D status of alpacas. The relationship between plasma 25-OH D(3) and plasma Pi was also investigated. RESULTS: Vitamin D status was significantly affected by month of sampling, with low values in late winter and high values in summer. Plasma vitamin D concentrations increased with age, were higher in alpacas with light fleeces than in those with dark fleeces and were also higher in the Suri than in the Huacaya breed. Plasma Pi concentrations were generally lower in alpacas with plasma 25-OH D(3) values < 25 nmol/L. CONCLUSIONS: Young alpacas with dark fleeces are most at risk from vitamin D insufficiency in late winter in southern Australia. The present study indicates that plasma Pi values are not a reliable indicator of vitamin D status of alpacas as assessed by plasma 25-OH D(3) concentrations.

An assessment of the safety of copper heptonate for parenteral therapy in sheep.

OBJECTIVE: To investigate any adverse effects of an intramuscular injection (i.m.) of copper heptonate (CuHep) in sheep. PROCEDURE: Merino wethers about 9 months old were retained in pens and given 1 or 2 mg Cu/kg body weight as CuHep or no Cu treatment. Sheep were weighed and samples of blood for haematology, Cu and enzyme assay and tissues for Cu and Fe assay were collected before and at intervals over 21 days after treatment. RESULTS: CuHep was removed from the injection site within 7 days of treatment and most of it was retained in the liver. Wethers had adequate liver Cu reserves before treatment and the higher dosage of CuHep raised liver Cu to values associated with Cu toxicity. No clinical signs of Cu toxicity were evident. Transient increases in plasma activity of the liver enzyme glutamate dehydrogenase suggested mild liver necrosis due to CuHep, but there was no histopathological evidence of liver necrosis 7 days after treatment. CONCLUSIONS: I.m. injection of Cu as CuHep appears to be readily transferred to the liver. No significant necrosis is caused at the injection site.

Comparison of copper heptonate with copper oxide wire particles as copper supplements for sheep on pasture of high molybdenum content.

OBJECTIVE: To assess the effectiveness of intramuscular injection of copper heptonate (CuHep) and an oral dose of copper oxide wire particles (COWP) in preventing Cu inadequacy in adult and young sheep on pasture of high Mo content. DESIGN: Field experiments with flocks of mature Merino wethers and crossbred weaners. PROCEDURE: Adult wethers were given 25 or 37.5 mg Cu as CuHep, 2.5 g COWP or no Cu treatment. The weaners were given 12.5 or 25 mg Cu as CuHep, 1.25 g COWP or no Cu treatment. At intervals over the next 12 (adults) or 8 (weaners) months the sheep were weighed and samples of blood and liver were collected for trace element assay. Wool samples collected from the adults at the end of the experiment were assessed for physical characteristics. RESULTS: The higher dosage of CuHep raised liver Cu above control group values for at least 9 months in adults and 3 months in weaners. The lower dosage of CuHep was similarly effective for 3 months in adults but was without effect in weaners. In adults the response to COWP matched that to the higher dosage of CuHep; in weaners it was greater, lasting at least 5 months. No changes indicative of Cu deficiency, apart from a depressed body weight in adults, were seen. CONCLUSIONS: In sheep on pasture of high Mo content a single intramuscular injection of CuHep providing 37.5 mg Cu to adults or 25 mg Cu to weaners will raise liver Cu reserves for at least 9 and 3 months respectively and may be an acceptable alternative to COWP for preventing seasonal Cu deficiency in sheep in southern Australia.

Stability of vitamin E in blood and plasma from cattle, sheep, and pigs.

The stability of alpha-tocopherol concentrations in sheep, cattle, and pig blood and plasma stored at different temperatures was examined. For all species, the vitamin was stable for at least 6 days in plasma stored at -20 C, 4 C, and 25 C and in blood stored at 4 C and 25 C. For sheep and cattle, the vitamin was stable for at least 6 days in plasma stored at 37 C, but it was unstable in blood from all species stored at 37 C and in pig plasma stored at 37 C.

Vitamin D doses for alpacas (Lama pacos).

OBJECTIVE: To assess the effectiveness of cholecalciferol (D3) doses for maintaining adequate vitamin D status in crias and adult female alpacas at pasture. DESIGN: A field experiment during winter and early spring in a herd on a farm in South Australia. ANIMALS AND PROCEDURE: Crias, usually less than 6 months of age and female alpacas, aged 2 to 6 years, were given a single subcutaneous dose of 0, 1000 or 2000 IU D3/kg body weight. Plasma concentrations of 25-hydroxycholecalciferol (25-OH D3), phosphorus, calcium and vitamins A and E and alkaline phosphatase activity were measured at intervals over a period of 16 weeks after treatment. RESULTS: Crias not given a vitamin D supplement had reduced growth rate during winter and one animal showed clinical signs of rickets. Vitamin D treatment had no effect on the body weight of mature females. Vitamin D supplements increased the 25-OH D3 and phosphorus concentrations in plasma of both crias and adult females; alkaline phosphatase activity was not affected by treatment. CONCLUSION: It is suggested that for alpacas in southern Australia a subcutaneous dose of 1000 IU D3/kg body weight to crias in late autumn and again in mid winter and to adult females in mid winter should prevent vitamin D inadequacy.

Vitamin B12 responses to cobalt pellets in beef cows.

OBJECTIVE: To assess the effectiveness of cobalt pellets in maintaining adequate vitamin B12 in beef cows on pasture of low cobalt content. DESIGN: A field experiment in a herd grazing cobalt deficient pasture. ANIMALS: Mature Murray Grey cows. PROCEDURE: Cows were given a single oral dose of 0, 1, 2 or 4 cobalt pellets (30 g pellets containing 30% by weight cobaltic oxide) with a selenium pellet and a grub screw. Samples of blood, liver, faeces and milk for chemical analysis were collected at intervals over a period of 2 years after treatment. RESULTS: A single cobalt pellet raised liver vitamin B12 concentration of cows above that of untreated cows for at least 28 weeks, and 2 or 4 pellets for 57 weeks. Plasma vitamin B12 concentration was an unreliable indicator of the effectiveness of cobalt pellet therapy. Milk vitamin B12 and faecal cobalt concentrations increased in response to cobalt pellet therapy. CONCLUSION: These studies show that one cobalt pellet will prevent vitamin B12 inadequacy in beef cows for between 28 and 57 weeks; two or four pellets will prevent inadequacy for 57 to 75 weeks. Milk vitamin B12 concentration may be a useful indicator of the effectiveness of cobalt pellets in increasing the vitamin B12 supply in lactating cows.

Copper oxide powder as a copper supplement for sheep.

The ability of oral doses of copper oxide powder to raise liver and blood copper concentration was examined in penned sheep given a pelleted diet containing 4 mg of copper per kg dry matter. Merino sheep of similar live weight and liver copper concentration were allocated at random to one of six treatment groups of four sheep each. Treatment groups received nil, 2.5 g, 5 g, 10 g, 20 g and 40 g of cupric oxide powder. The cupric oxide powder of sieve size 250-350 microns was effective in raising the liver copper concentration for at least 12 weeks. The large particles of oxide powder were retained in the gut for at least 13 days after dosing. Sheep given 10-40 g doses of cupric oxide powder were at risk of copper toxicity, as indicated by elevated plasma enzyme activities, liver copper concentrations and reduced liveweight gains. It was concluded that a 2.5 g dose of cupric oxide powder could be used to prevent short periods of copper deficiency in sheep at pasture without risk of copper toxicity.

Long-acting selenium treatments for sheep.

An intraruminal selenium (Se) pellet and a subcutaneous depot of barium selenate, equivalent to 1.6 mg Se/kg body weight, were each effective in maintaining increased blood Se concentrations for at least 200 weeks in ewes at pasture. These treatments given to the ewes 23 to 26 weeks before lambing increased the Se status of their lambs for 4 to 6 months.

Sex-related responses to vitamin B12 and trace element supplementation in prime lambs.

Bodyweight, plasma vitamin B12 and blood selenium concentrations were monitored in prime lambs given different forms of supplementation at 2 sites in separate years. At the first site treatment groups comprised control, vitamin B12 injection, selenium given orally and a combination of vitamin B12 and selenium. At the second site cobalt and selenium supplied in a glass bullet was compared with an untreated group. Significant sex-related responses were observed to treatment in terms of bodyweight and at site 2 in plasma vitamin B12 concentrations. A marked bodyweight response to glass bullet supplementation was observed in castrated male lambs but not in ewe lambs. These studies show that sex differences should be considered when investigating trace element deficiencies.

Copper and selenium deficiency in cattle: an evaluation of methods of oral therapy and an observation of a copper-selenium interaction.

The efficacies of oxidised copper particles, selenium bullets and soluble glass bullets in raising the copper and/or selenium reserves of young cattle marginally deficient in both trace elements were examined. Selenium bullets were associated with a reduced copper uptake when selenium bullets and oxidised copper particles were given together. Responses in liveweight gains to trace-element supplementation and relationships between copper or selenium in blood components and liver are presented.

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.

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.

Control of alpha-mannosidosis in Angus cattle.

Tests for the detection of animals heterozygous for alpha-mannosidosis were undertaken on samples taken from 34,203 cattle registered with the Angus Society of Australia. Results indicates 1,836 (5.4%) of the animals were heterozygotes. Heterozygotes were detected in 214 (51%) of the herds examined.