Control of Mineral Imbalances in Cattle and Sheep:
A Reference Manual for Advisers and Vets

Phil Rogers MRCVS⁽¹⁾ & Tom Gately MAgrSc, MS, PhD⁽²⁾

Contents | Tables | Acknowledgements | Comparative costs |

CONTENTS

Introduction | Background to the Teagasc Farm Nutrient Profile Service

PART 1: METHODS OF SUPPLEMENTATION

Minerals and Vitamins

Mineral stores in the body and timing of supplementation

Methods of mineral supplementation of cattle and sheep

Free-access systems (blocks, licks, loose minerals)

Rates of oral supplementation of stock with minerals

Trace element supplements for cattle and sheep

1. Effective oral trace element supplements for cattle and sheep
2. Periodic pasture dressing with trace elements
3. Oral trace elements via the water supply to grazing cattle
4. Veterinary products for trace element supplementation
5. Soil fertilisation with trace elements
6. Periodic drenching with trace element supplements
7. General warnings in connection with trace elements

PART 2 : CONTROL OF SPECIFIC MINERAL IMBALANCES IN STOCK

Control of Calcium (Ca) Imbalance, Hypocalcaemia and Milk Fever in Cattle and Sheep
Control of Cobalt (Co) Deficiency in Cattle and Sheep
Control of Copper (Cu) Deficiency/Molybdenum (Mo) Excess in Cattle and Sheep
Control of Iodine (I) Deficiency in Cattle and Sheep
Control of Magnesium (Mg) Deficiency, hypomagnesaemia and tetany in Cattle and Sheep
Control of Manganese (Mn) Deficiency in Cattle and Sheep
Control of Phosphorus (P) Deficiency in Cattle and Sheep
Control of Selenium (Se) Deficiency in Cattle and Sheep
Control of Selenium (Se) Toxicity in Cattle and Sheep
Control of Sodium (Na) Deficiency in Cattle and Sheep
Control of Zinc (Zn) Deficiency in Cattle and Sheep
Addendum: Comparative costs of mineral supplements for cows from 1 month pre- to 4 months post- calving

Summary

1. Commercial mineral-vitamin mixes
2. Oral trace element supplements alone
3. Veterinary products
4. Methods of last resort

Tables

Abbreviations used in the text
Suppliers of Trace Element Salts
Acknowledgements

This manual provides necessary information to be used in conjunction with the Teagasc Farm Nutrient Profile. It describes the various methods that may be used to correct and prevent mineral imbalances in cattle and sheep. The text will be used mainly by Teagasc advisers, to help them to make specific recommendations to their clients on the control of any mineral problem identified in the Farm Nutrient Profile.

The text will be useful also to other professionals who serve our cattle and sheep farmers: vets, agricultural consultants, nutritionists and specialists in the mineral mix and feed-compounding trade.

The information presented in the manual is both detailed and technical. It is not written for casual "lay" readers, but it will be useful to some of the progressive farmers who use the Teagasc Farm Nutrient Profile, or the Grange Blood Analysis Service. Therefore, farmers who read this manual are urged to discuss the various methods of control with their Teagasc advisers and veterinary surgeons, in order to select the most appropriate method for their farm and in order to have the calculations of the dose rates checked by competent professionals.

The manual is presented in two major parts:

1. METHODS OF SUPPLEMENTATION

Part 1 outlines the various the various appropriate methods and systems of mineral and trace element supplementation for cattle and sheep.

2. CONTROL OF MINERAL IMBALANCES

Part 2 presents the specific control measures for mineral imbalances, including rates of supplementation for each of the methods addressed in part 1.

BACKGROUND TO THE TEAGASC FARM NUTRIENT PROFILE SERVICE
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Apart from economic factors (low market prices, high input costs), the main causes of low profit margins in cattle and sheep enterprises are: reduced feed intake, poor quality winter feed, poor grassland management, parasitism and chronic infections.

Nationally, mineral imbalances are far less important to profit margins than those factors. However, mineral imbalances can cause major loss of profit to some farmers.

The Teagasc Farm Nutrient Profile is especially useful in investigating and correcting ongoing animal disorders associated with suspected mineral imbalances. It may be used also as a periodic check of the mineral status of farms, in order to forestall possible problems in the future.

Control and prevention of mineral imbalances are usually straight-forward, once the underlying imbalances and their causes are identified. Correction of the imbalances can help farmers to maximise the efficiency of their livestock enterprise.

The provision of a high-quality mineral-vitamin mix is the cheapest way of supplying a balanced cocktail of minerals and vitamins to stock. The most reliable way is to incorporate the correct amount of mineral-vitamin mix into the daily allowance of concentrate ration. The second best way is to divide the correct daily allowance of mineral-vitamin mix into 2 or 3 parts and to sprinkle the mix over the easy-feed or roughage diet in 2 or 3 times /d.

Mineral-vitamin mixes are based on simple compounds: salt, limestone, di-calcium phosphate, calcined magnesite, sodium selenite, potassium iodide or iodate and sulphates of copper, cobalt, manganese and zinc. Sweeteners and Vitamins A, D3 and E are usually added, together with agents to prevent rain-damage.

The formulation and blending of complex mixes is a specialist task. Farmers are advised not to undertake the task themselves but to use products from reliable manufacturers.

Commercial retail prices of mineral-vitamin mixes range from IR 200-1000/ tonne. The cheapest are not necessarily the worst, nor are the dearest necessarily the best. Some commercial mixes do not provide a good balance of minerals and vitamins. Therefore, farmers should discuss the suitability of various commercial products with their Teagasc advisers. Our advisers, backed up by specialists and research workers, are trained to assess, from the specification and the proposed daily allowance of the mix, the suitability of any commercial mix for different types of stock and for different diets. Farmers, having got this expert opinion, can select a cheap but effective mix to solve their problems. Alternatively, they may discover that they do not need to feed any minerals. For example, dairy cows are often fed 150 g of extra minerals/d for 90-120 days after calving (13.5-18.0 kg/cow at a cost of, say, IR 500/tonne). A dairy farmer with 80 cows could save 1-1.4 tonnes of expensive minerals (IR 500-700) per season if the minerals were not needed on silage and good dairy ration.

Many excellent veterinary products to correct mineral imbalances are available but they are expensive for routine control of multiple mineral imbalances. Although general dose rates of veterinary products and their usage are suggested in this manual, they may need alteration in specific cases. Farmers are urged to consult their own local vets as regards the most applicable and economic methods for their farm.

ESSENTIAL NUTRIENTS: Certain nutrients are essential for optimal animal health. They are in three classes: vitamins, major elements and trace elements.

Vitamins: Table 5 shows suggested daily vitamin supplements (iu/head/d) for stock. Most mineral mixes and blocks, especially those used in winter and spring, contain Vitamins A, D3 and E. Vitamins B1 and B12 are added occasionally. Vitamin activity usually declines with storage time in mineral supplements and compound feeds. In an effort to ensure that the product contains not less than the stated amount after some months of storage, many compounders add double the stated amount and some mineral-vitamin mixes contain 3-10 times more vitamins than are needed.

Vitamin A: Good pasture contains adequate levels and grass silage and green hay usually have adequate levels. However, cereals, bleached hay, straw, roots and byproducts of the alcohol-sugar industries can be low in vitamin A.

Vitamin D3: Sunlight, interacting with the skin, allows animals to synthesise their requirements of vitamin D3. A supplement is needed in winter when sunlight is scarce or animals are housed.

Vitamin E: Good pasture usually contains adequate levels of vitamin E. Though the level in freshly ensiled material may be high, fermentation processes and spoilage may reduce the vitamin E level before the silage is fed. Wet cereals or grains, bleached hay, straw, root crops and byproducts of the alcohol-sugar industries can be low in vitamin E. Storage of grain, especially that treated with propionic acid, can reduce vitamin E levels markedly. Some authorities recommend 100-1000 iu vitamin E/d for cows. These supplementation rates are much higher than those shown in Table 5 (240-300 iu/d). High levels of vitamin E are said to reduce mastitis incidence and milk cell counts.

B vitamins: Rumen microbes usually synthesise enough vitamins B1 and B12 to meet the animal's needs if the cobalt supply is adequate and if anti-vitamin factors (such as thiaminases) are absent. Thiaminases in the rumen can cause vitamin B1 deficiency, which can lead to cerebrocortical necrosis (CCN), blindness and nervous signs.

Vitamin supplements at pasture: Vitamin supplements (A, D3, E, B1 or B12) rarely are needed by cattle or sheep on good pasture. Possible exceptions are:

(a) As grass tetany is usually associated with stress and vitamin requirements can be increased by stress, it is advisable to include a vitamin supplement in mixes designed for tetany control in cows and ewes.

(b) High levels of vitamin E in the month before mating may improve fertility in cows and ewes and high levels of vitamin E may help to reduce the incidence of subclinical mastitis.

(c) If vitamin B1 or B12 deficiency is diagnosed, the relevant vitamin can be given, especially by injection, pending correction of the Co deficiency or removal of the anti-vitamin factors.

Vitamin supplements on winter feeds: Grass silage and cereal-protein concentrates are the most common winter feeds. Other feeds include hay, straw, byproducts (brewers' and distillers' grains, molasses, beetpulp etc), brassicas (rape, kale) and roots. Because winter feeds are so varied, it is difficult to formulate a minimum vitamin supplement to suit all situations. At least part of the daily total requirement of Vits A, D3 and E should be supplied during the winter. Depending on the feeds used, between 20 and 100% of the total daily requirement of the vitamins should be provided. (Total daily requirements for vitamins are usually higher than the daily rates of supplementation suggested in Table 5). There is no need for routine inclusion of B vitamins in winter supplements if Co status is adequate and if thiaminase levels are normal in the rumen.

Vitamin A: One should add 20-60% of the total daily requirement of vitamin A on diets of silage + concentrates and 50-100% of total daily requirement on other diets.

Vitamin D3: One should add 50-100% of the total daily requirement of vitamin D3 in winter.

Vitamin E: One should add 20-60% of the total daily requirement of vitamin E on diets of silage + concentrates and 50-100% of total daily requirement on other winter diets. High levels of vitamin E are needed when high levels of roots (e.g. fodder-beet) or grains (especially wet or propionic acid-treated grain) are fed.

Major elements: The major elements include calcium (Ca), phosphorus (P), magnesium (Mg) and sodium (Na). Nitrogen (N), potassium (K) and sulphur (S) can act as antagonists to other minerals.

Trace elements: The trace elements include cobalt (Co), copper (Cu), iodine (I), manganese (Mn), selenium (Se) and zinc (Zn). Molybdenum (Mo) and iron (Fe) are powerful Cu-antagonists.

Mineral imbalances and deficiencies are common in Irish herds and flocks. Mineral imbalance has 3 forms: (a) non-clinical, (b) sub-clinical and (c) clinical. Non-clinical imbalance is widespread and is more common than sub-clinical imbalance, which is more common than clinical imbalance.

(a) Non-clinical imbalance: Herd health and productivity are normal. Diagnosis is based on mineral imbalance in blood, feed or soil in the absence of health problems. Confirmation is by the absence of response to supplementation with the deficient mineral(s). If the price is cheap, mineral supplements are justified as an insurance against the possibility that non-clinical deficiency can become sub-clinical or clinical. A Pre-Calver mineral mix is a good investment, even in healthy herds, as it costs only 2.5-5.0 p/cow/d for the last month before calving.

(b) Sub-clinical imbalance: There are few or no clinical signs but productivity (fertility, growth rate, milk yield, milk quality) is depressed in 20-50% of the group. Diagnosis is difficult: other causes of poor performance (poor grassland quality or management, poor quality or quantity of winter feed, parasitism, chronic infections, sequels to calfhood diseases etc) must be eliminated. Then, a severe mineral imbalance in blood, feed or soil is suggestive. Confirmation is by a dramatic response in productivity to supplementation with the deficient mineral(s). Some herds with uncorrected sub-clinical signs may develop clinical signs later.

(c) Clinical imbalance: Some or all of the clinical signs are present in 10-30% or more of the herd and another 10-40% usually have lower product-ivity (subclinical signs). Diagnosis is based on the history, clinical signs and, sometimes, post-mortem findings. It is confirmed by blood, feed and soil tests and by a dramatic response to supplementation with the deficient mineral(s).

Mineral imbalances may arise singly or in various combinations. Imbalances of major elements (Ca, P, Mg, Na) may cause rickets, lameness, milk fever, lambing sickness, tetany, reduced appetite, reduced milk yield and depraved appetite. Deficiency of trace elements (Co, Cu, I, Mn, Se, Zn) may cause illthrift, abortion/placental retention/perinatal calf and lamb deaths, reduced immunity in calves, lambs, cattle and sheep, susceptibility to bacteria and parasites, infertility in cows and ewes, reduced fertility in bulls and rams, lowered milk yield, lameness, slow healing of wounds and poor skin/hair/fleece quality.

Differential diagnosis: Such clinical and subclinical problems can arise due to many causes other than mineral imbalances. Therefore, before the cause of such problems is attributed to mineral imbalances, the vet should examine the herd or flock (to eliminate other disorders, such as chronic poisoning, parasitism, infection etc). Meanwhile, the Teagasc adviser should examine the management, housing, farming practices etc. Finally, laboratory tests (blood, feed, soil, as in the Teagasc Farm Nutrient Profile) can identify specific mineral imbalances.

In herds or flocks with clinical or subclinical disorders, once the nature and severity of the mineral imbalances are recognised, they usually can be treated and prevented by provision of the correct balance of mineral supplements. However, in herds or flocks with non-clinical disorders, mineral supplementation usually does not improve profitability in the short-term. However, if the price is cheap, mineral supplements may be justified as an insurance against the possibility that non-clinical deficiency can become sub-clinical or clinical.

Mineral mix formulations: Examples of mineral mix formulations, suggested rates of oral supplementation with minerals and vitamins, suggested levels of trace element levels in finished rations and carriers, Mg levels in cow and ewe rations and the mineral content and price of common trace element compounds are given in Tables 1 to 10.

Mineral stores in the body: Minerals can be classed into three types as regards effective stores and recycling in the body:

Good stores and recycling (Ca, P, Na, Cu, Se): These elements can be short in the diet for weeks or months without causing observable problems, provided that the body stores were "full" before the period of shortage. In that period, mobilisation from the stores helps to maintain normal levels in blood, body fluids of cells that need those minerals. If a period of plentiful supply of the element follows a period of shortage, the stores are replenished again. Thus, months of supplementation with Cu and Se indoors confers good protection for a period after turnout, even if the supplements are removed at turnout. As a rough guide, 1 month indoors on a high Cu or Se supplement before turnout confers about 1 month's cover after removal of the supplement at turnout.

Medium stores and recycling (I): These elements have medium stores, which give protection for only 2-3 weeks in periods of shortage. Thus, months of supplementation with I indoors may not maintain I status during the breeding period at grass if I supplements are removed at turnout to I-deficient pasture. In I-deficient groups, oral I doses are needed daily, but doses at 1-2 week intervals also are effective.

Poor stores and recycling (Mg, Co): Although bone and other body cells contain a lot of Mg, those stores are "locked", i.e. are not available for release in times of Mg shortage. Thus, provision of Mg supplement for weeks before the tetany risk period has little value, except to train the animals to take the supplement. Mg supplement is needed daily throughout the risk period. Co has no effective recycling in ruminants and no effective store exists in the body. Therefore, Co-deficient animals need Co supplement very frequently, preferably daily, although dosing at intervals of 14 days is effective in Co-deficient stock.

Timing of administration of mineral supplements (including veterinary products) depends on the timing of the clinical or subclinical problems.

In chronic conditions, such as illthrift, infertility, depressed milk yield, chronic scour etc, give supplements in time to allow them to act for some weeks before the expected onset of the problem.

In herds or flocks with problems confined to late pregnancy, parturition or early calf/lamb losses, the dams are treated in late pregnancy. For example, to prevent stillbirth in calves due to I deficiency, the dams are treated with I (orally or by skin application) for 4-5 weeks before calving; to prevent swayback in lambs in Cu-deficient flocks, the ewes are treated (preferably by Cu oxide capsules) at mid pregnancy; to prevent stillbirth/weak calf syndrome/placental retention in cows, due to Se deficiency, the cows are treated about 1 month before calving; to prevent infertility in cows, due to Mo-induced Cu deficiency, the cows are treated soon after calving, as Cu given pre-calving is diverted to the foetus and little remains for the cow post-partum; to prevent infertility in cows, due to Se deficiency, the cows are treated soon after calving, or about 1 month before breeding. To prevent illthrift or scouring in calves, yearling cattle and lambs, due to Cu deficiency, begin treatment about 1 month before the expected onset of the problem.

Dosage and frequency of administration of veterinary products as mineral supplements depends on the weight of the animals, the degree of challenge to the mineral status and the chemical potency and form of the compound to be administered. Although general dose rates of veterinary products and their usage are suggested in this manual, they may need alteration in specific cases. Farmers are urged to consult their own local vets as regards the most applicable and economic methods for their farm. Heavier animals need larger doses. More frequent doses are needed in groups exposed to high challenge, such as on feeds that contain antagonists to the deficient mineral. Some products are short-acting; others are long-acting. See the sections on the Control of specific deficiencies (below).

Mineral mix formulations: Examples of mineral mix formulations, suggested rates of oral supplementation with minerals and vitamins, suggested trace element levels in finished rations and carriers, Mg levels in cow and ewe rations and the mineral content and price of common trace element compounds are given in Tables 1 to 10.

Normal mineral status in animals usually can be ensured if adequate mineral supplements are given. These are justified if the health history suggests clinical or sub-clinical signs of deficiency. They may also be justified in high-yielding healthy (non-clinical) herds, as a preventative to non-clinical deficiency becoming sub-clinical or clinical. Methods of Mineral Supplementation

Warning: Mineral supplements for use in calved cows have different formulations to those for use in dry-cows or dry stock. Mineral supplements for use in lambed ewes have different formulations to those for use in dry-ewes or lambs. Do not feed cattle minerals to sheep and vice-versa.

General methods of mineral supplementation: Mineral supplements may be given in many ways (oral supplements, water medication, veterinary products, foliar dusting or spraying or mineral application to soil). Whichever method is chosen, the correct dose or application rate is essential.

Mineralised concentrate rations: If mineral mixes are not fed, ensure that Co, Cu, I, Mn, Se and Zn (at least) are included in the concentrate feed for cows (see Table 6).

Mineral mixes are best fed in the concentrate ration or sprinkled over easy-feed silage 2-3 times/d, or mixed with 3-4 times their weight of palatable carrier (say molassed beet pulp, or rolled barley 94% + molasses 6%). Use reputable minerals and feed at the recommended rates only.

Free-access systems (blocks, licks, loose minerals): Daily intake of minerals by free-access to blocks, licks and loose minerals in troughs is very variable between animals. Free-access systems (wet or dry licks, blocks, loose minerals in troughs etc) are not as reliable as fixed-rate daily mineral supplementation. This is especially so in winter, when fixed-rate mineral feeding is easy. Even at grass, fixed-rate mineral feeding in feed, palatable carrier, or water is more reliable than free-access systems. Fixed-rate feeding of supplements is much more reliable in preventing mineral/vitamin deficiency in animals.

Table 1 shows mineral mix formulations for cows and ewes. Table 2 shows mineral mix formulations for drystock (cattle and lambs). Table 3, Table 4 and Table 5 show suggested optimum supplementation levels of Major Elements, Trace Elements and Vitamins respectively for Irish livestock. In the absence of other mineral sources, such as in compound ration or as veterinary medication, supplements for long-term routine use that provide less than the minimum amounts of major- or trace elements in the daily intake are inferior.

Levels of oral mineral/vitamin supplements advised by different National Advisory Groups vary considerably. The rates given in Table 3, Table 4 and Table 5 are guidelines for cattle reared under Irish conditions. Irish research showed that the Cu and Se requirement of cattle is higher than in other countries. Thus, the suggested supplementation rates of Cu and Se are higher than "international standards". (Pending a 2-year reassessment of the daily requirements for Se, the rates in Table 4 are recommended). The suggested vitamin allowances are also higher than those from some other authorities.

The best methods of trace element supplementation are:

1. effective oral supplements;
2. foliar spraying;
3. chelated trace elements in the drinking water;
4. effective veterinary products.
5. Soil application may be considered in simple deficiency of Co, Se or Cu.
6. Periodic drenching at intervals of 2-3 weeks may be considered also.

 

1. Effective oral trace element supplements for cattle and sheep
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   Daily oral supplementation rates: Optimum daily oral supplementation rates of trace elements for cattle and sheep under Irish conditions are shown in Table 4.

   Optimum daily oral supplementation rates for cows are: Se 3-5 mg; Co 5-10 mg; Cu 150-450 mg; I 12-60 mg; Mn 335-415 (and maybe 980) mg; Zn 335-750 mg/cow/d. These dose rates ignore the trace element levels in forage and roughage. Oral supplements (in compound feed, mineral mixes, blocks, etc.) that give those amounts daily ensure normal trace elements status pre- and/or post-calving.

   Oral supplements that provide less than the minimum daily allowance are unlikely to be effective. If in doubt, choose medium levels, i.e. 300 mg Cu, 4 mg Se, 7.5 mg Co, 45 mg I, 563 mg Zn and 400 mg Mn/cow/d. However, the upper levels were used widely without problemsin recent yearsprovided that no other supplements were used.

   European Community (EC) Regulation on Trace Elements in feed: The EC (Additives in Feedingstuffs) (Amendment) regulation, 1991, S.I. No. 124 of 1991 gives the following as the maximum content of trace element in the complete feedingstuff for cattle and sheep, and the value converted to mg/kg DM, assuming a DM content of 88% in "complete feeds":

   Element	Animal type	Max level (mg/kg) permitted in complete feed	Max level (mg/kg DM) permitted (assuming 88% DM in "complete feed")
   Cobalt (Co)	Cattle/sheep	10	11.36
   Copper (Cu)	Sheep	15	17.05
   	Calves, milk replacer	30	34.09
   	Calves, other complete feedingstuffs	50	56.82
   	Other species and categories (cattle)	35	39.77
   Iodine (I)	Cattle/sheep	10	11.36
   Manganese (Mn)	Cattle/sheep	250	284.09
   Selenium (Se)	Cattle/sheep	0.50	0.57
   Zinc (Zn)	Cattle/sheep	250	284.09

   Assuming a dry matter (DM) of 88% in complete feedingstuffs and a DM intake of 2-3% of liveweight (LW), maximum daily trace element intake from the complete diet allowed for 650 kg cows under EU regulations are: Se 7.4-11.1 mg; Co 143-215 mg; Cu 515-776 mg; I 143-215 mg; Mn 3693-5540 mg; Zn 3693-5540 mg/cow/d.

   Thus, the supplementation levels that we recommend for Co, I, Mn and Zn are well within the maxima permitted under current EC regulations, even at the lower DM intake (2% of LW) and the recommended supplementation levels for Se and Cu are just below the maxima permitted under current EC regulations at the lower DM intake (2% of LW), and are well below the maxima allowed at DM intakes of 3% of LW. [Our Se and Cu recommendations are higher than those used in many other countries but they are made on the basis of years of research in cattle under Irish conditions and the recommendations are under continuing review]

   Minerals in the concentrate ration: Accurate formulation of the concentrate diet is the best and cheapest way to give oral supplements. No other mineral supplement is needed if the diet is properly balanced. Table 6 shows the trace element levels in compound dairy concentrate to give the daily allowances shown in Table 4.

   Carriers for trace elements: Small amounts of carrier can be used to supply cattle and sheep with optimum amounts of trace elements. The carrier can be rolled barley or beet pulp, to which the correct amount of minerals are added. If the carrier is to be group-fed in troughs, it is essential to allow adequate trough-space and to add molasses (5% total weight) to make it very palatable. The amounts of carrier (including minerals and molasses) needed are:

   Cows and adult cattle	450 g
   Yearling cattle	350 g
   Weanling cattle	250 g
   Ewes	112 g
   Lambs	6 g/10 kg LW

    

    

   Table 7 shows the formulation of carriers to supply the daily trace element allowances in Table 4.

   Dairy or beef cows pre-calving

   If cows have mineral-related problems at calving (milk fever in more than 8% of cows or retained placenta in more than 4% of cows) or total calf losses above 8% (including late abortion + perinatal calf deaths + deaths within 3 weeks of birth), then a pre-calver (dry-cow) mineral, high in trace elements, fed for 4-6 weeks before calving may be used. As the cost is small, a Pre-Calver mineral is a good insurance against perinatal problems in intensive dairy herds and in pedigree beef cows.

   Minerals in concentrate ration: Beef cows seldom, if ever, are fed concentrates pre-calving. Although most dairy farmers feed no concentrates pre-calving, some do. If concentrates are fed, the feed compounder may be persuaded to adjust the levels of trace elements in the dry-cow concentrate, so that the daily supply of concentrate gives the desired amounts (see Table 4). For example, if the farmer normally feeds 2 kg of concentrate/cow/d, ensure that it contains 75-225 mg/kg Cu, 1.5-2.5 mg/kg Se, 2.5-5.0 mg/kg Co, 15-30 mg/kg I, 188-375 mg/kg Zn and 175-225 mg/kg Mn, as fed. If less than or greater than 2 kg is fed, adjust the mineral/vitamin levels up or down (as in Table 6), so that the desired amount of mineral/vitamin goes into the daily allowance of concentrate.

   Minerals in a palatable carrier: A good quality pre-calving mineral mix can be fed in a palatable carrier to dairy cows (total allowance 450 g/cow/d. If the pre-calving mineral is to be fed at 100 g/cow/ day, the formulation of the medicated carrier is: 100 g pre-calving mineral + 329 g rolled barley + 21 g molasses) = total 450 g/cow/d. This can be fed once/d in the parlour. It can be fed also in troughs, provided all cows can get access together. Alternatively, it can be sprinkled over the easy-feed 225 g/cow, twice/d).

   Pre-calving mineral mixes: The usual feeding rate is 100 g of mineral mix/head/d. To reduce milk fever risk, insist on low-Ca (0-6%) and high-Mg (13-17%) levels in pre-calving mineral mixes. P levels are optional in the range (0-14%), depending on the forage. (Cows on good silage need little or no P supplement pre-calving). Na (as salt) is the usual "filler". The Na content can range from 5-18%.

   Insist on high trace element levels (especially Cu, Se, Co and I) in pre-calving mineral mixes, i.e. 1500-4500 mg/kg Cu, 30-50 mg/kg Se, 50-100 mg/kg Co, 300-600 mg/kg I, 3350-5000 mg/kg Zn and 3350-4150 mg/kg Mn if the feeding rate is 100 g/cow/d. Sprinkle the mix 2-3 times/d (50-33 g/cow each time) over the easy-feed silage. See Table 1, which also shows mineral mix formulations for ewes in late pregnancy.

   Lactating dairy or beef cows indoors

   After calving, the demand for Ca, P and Na increases for lactation. Many silages are marginally low in P and Na and high-yielding cows should normally get Ca, P and Na supplements on silage. Consider feeding mineral mixes high in trace elements during the winter, unless the compound feed is known to supply adequately high levels of trace elements.

   Minerals in concentrate ration: Dairy cows usually get concentrates indoors after calving but beef cows seldom do. The feed compounder may be persuaded to adjust the levels of trace elements in the dairy concentrate, so that the daily supply of concentrate gives the desired amounts (see Table 4). For example, if the feeding rate is normally 6 kg concentrate/cow, insist on 25-75 mg/kg Cu, 0.50-0.85 mg/kg Se, 0.84-1.67 mg/kg Co, 5-10 mg/kg I, 63-125 mg/kg Zn and 58-75 mg/kg Mn in the concentrate, as fed. If less than or greater than 6 kg is fed, adjust the mineral/vitamin levels up or down, so that the desired amount of mineral/vitamin goes into the daily allowance of concentrate. Table 6 shows the correct formulation of dairy rations to provide the amounts of trace elements recommended in Table 4.

   Post-calving mineral mixes for housed cows: If usual feeding rate is about 125 g of mineral mix/head/d use a mineral mix with 7-17% Ca, 7-17% P, 4-10% Mg, 7-20% Na, depending on the type of forage and concentrate fed.

   Ensure that post-calving mineral mixes are high in trace elements (especially Cu, Se, Co and I). If fed at 125 g/cow/d, use a mineral mix with 1200-3600 mg/kg Cu, 24-40 mg/kg Se, 40-80 mg/kg Co, 240-480 mg/kg I, 2680-6000 mg/kg Zn and 2680-3320 mg/kg Mn. If less than or greater than 125 g/cow/d is fed, adjust the mineral/vitamin levels in the mix up or down, so that the desired amount (see Table 4) of mineral/vitamin goes into the daily allowance of mix. See Table 1, which also shows mineral mix formulations for ewes in post-lambing.

   Lactating cows at grass: During the period of tetany risk, dairy and beef cows need a daily supplement of Mg (see Control of Mg deficiency, hypomagnesaemia and tetany). Most farmers reduce or stop the feeding of concentrates after cows go to grass, but many are prepared to feed minerals in a carrier.

   Mineral mix in a carrier for cows at grass: To guarantee mineral intake by cows at grass, a good quality post-calving mineral mix can be fed in a palatable carrier (total allowance 450 g/cow/d. During the period of tetany risk, if Mg supplements are not given in another way, use a mineral mix with 13-31% (say 21%) Mg, in order to supply 20-40 g (say 30 g) Mg/cow/d in 130-150 g (say 150 g) of mineral mix/cow/d. If fed at 150 g/cow/d, use a mineral mix with 1000-3000 mg/kg Cu, 20-33 mg/kg Se, 33-67 mg/kg Co, 200-400 mg/kg I, 2500-5000 mg/kg Zn and 2200-2767 mg/kg Mn. If less than or greater than 150 g/cow/d is fed, adjust the mineral/vitamin levels in the mix up or down, so that the desired amount (see Table 4) of mineral/vitamin goes into the daily allowance of mix. If the post-calving mineral is to be fed at 150 g/cow/d, the formulation of the medicated carrier is: 150 g post-calving mineral + 281 g rolled barley + 19 g molasses) = total 450 g/cow/d. This can be fed once/d in the parlour. It can be fed also in troughs, provided all cows can get access together. See Table 1, which also shows mineral mix formulations for lambed ewes at risk of tetany.

   High I supplements for cows: If it is difficult to locate mineral mixes with I levels 400-600 mg/kg for use in cows, one may use a good standard mix (300 mg/kg I), plus a special iodised salt (1000 mg/kg I), 30 g of which supplies 30 mg I. Alternatively, 5% tincture of I (1 ml/cow, giving 50 mg I/cow) can be mixed in the trough water each day, or 7 ml of 5% tincture of I can be painted onto the thin skin of the pocket of the flank fold once per week for 5 weeks before calving or breeding.

   Mineral mixes for drystock (cattle and lambs): Table 2 gives formulations of trace elements in mineral mixes for drystock (cattle and lambs). The usual feeding rate of minerals to cattle is about 20 g/100 kg LW (110 g to fattening cattle at 550 kg). The usual feeding rate of minerals to lambs is about 8 g/20 kg LW (24 g to fat lambs at 60 kg).

   As with cows and ewes, mineral mixes can be fed to cattle and lambs in many ways: incorporated in the concentrate ration, sprinkled over easy-feed silage 2-3 times/d, or mixed with 3-4 times their weight of palatable carrier (say molassed beet pulp, or rolled barley 94% + molasses 6%).

    

    

2. Periodic pasture spraying with trace elements
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   Table 4 gives the suggested optimum oral supplementation levels of Trace Elements for stock. Oral supplementation (Part 1.a above), is the usual method of supplying trace elements but periodic pasture spraying may be a practical alternative for some farmers.

   Periodic pasture spraying with soluble salts of specific trace elements (such as Zn, Mn, Co, I, Se and Cu** (see footnote) can be used to provide those elements to grazing cattle or sheep that are confirmed to be deficient in them. The method has the advantage of being easy to use. [** Administration of oral Cu oxide capsules is the safest way to supplement sheep with Cu. While Cu may be administered to sheep by pasture spray, there is a risk of Cu-poisoning, especially in susceptible breeds, such as Texels, some continental breeds, and their crosses]

   Pasture spraying avoids the need dose each animal individually. For safe and effective control by pasture spraying, the following criteria must be met:

   Suitable sprayers: Usually, tractor-mounted sprayers are needed. This limits the usefulness of the method, as many farmers may not have the equipment.

   Frequency of spraying: Co and I have little or no storage or recycling in ruminants. Therefore, they must be given very regularly. For best results, repeat the spraying at intervals of 2 weeks.

   Adequate grass cover: The plots, just large enough to be grazed out in 1-2 days by the affected group, must have 9-11 cm grass cover (to hold the spray). Short grass or open swards may not hold the spray effectively.

   Optimal pasture height for intensive sheep production is 4-6 cm. Mean sward height of 6 cm or less may not have enough leaf area to hold 50% of the spray. In that case, a value of 2.5-3.0 may need to be assigned to factor (F) in the calculation of the amount of salt to apply (see method of calculation of spray rate, below). But, increasing the value of factor (F) increases the risk of toxicity if retention rate of the spray is much higher than expected. Thus, drenching sheep with trace element solutions every 2 weeks may be safer than pasture spraying on closely grazed swards.

   Dry weather only: Spraying may be considered only in dry weather. Soluble salts sprayed on grass are washed off easily by rain. The grass must remain dry during the period of supplementation.

   Trace element content of the salts used: Before calculating the amount of spray, double-check the mineral content in each salt to be used. See Table 10.

   Calculation of correct spraying rates for a 2-week supply

   Apply the correct amount of each salt evenly as a spray to the whole plot every 2 weeks. Excessive amounts or uneven spraying may carry a risk of toxicity. The calculation for each trace element salt is:

   T = (S.F.D.N.100/P)/(1000), where:

   T = total amount of the salt (g) for the group every 2 weeks

   S = supplementation rate of the element (mg/head/d), as in Table 4

   F = factor to allow for loss of salt by spraying. A loss of 50% is usually assumed. Thus the value of f is 2.

   D = number of days supply. This is usually set at 14.

   N = number of stock in each category to be supplemented

   100/P = factor to convert element to its common salt (100/percentage of element in the salt used)

   1000 = factor to convert milligrams of the salt to grams.

   Example 1: A group of 750 strong lambs is confirmed as needing routine Co and Cu supplement. The owner wants to spray grass with Co sulphate, (21% Co) and Cu sulphate (25.4% Cu) and to take the risk of Cu poisoning. The suggested Co and Cu supplement (see Table 4) for strong lambs is 0.4-1.0 mg Co/head/d (say 1 mg/head/d) and 0-12 mg Cu /head/d (say 6 mg Cu/head/d for strong lambs). The calculation of T is:

   (Co sulphate)

   T = (S . F . D . N . 100 /P ) / (1000) =

   (1 X 2 X 14 X 750 X 100 /21 ) / (1000) = 100.0 g

   (Cu sulphate)

   T = (S . F . D . N . 100 /P ) / (1000) =

   (6 X 2 X 14 X 750 X 100 /25.4) / (1000) = 496.1 g

   Thus, a spray of 100 g Co sulphate and 496 g Cu sulphate (see footnote 5) in water would be applied evenly to a well-grown sward in a plot large enough to carry 750 strong lambs for 1-2 days. This is enough for the 750 lambs, assuming that no rain falls while the lambs are in the sprayed plot. The procedure would be repeated once every 2 weeks.

   Example 2: A group of 75 cows at pasture is confirmed as needing I and Se supplement routinely (sprayed on grass as potassium iodide, 76.4% I and Na selenite, 30% Se). The suggested I and Se supplement (see Table 4) for cows is 12-60 mg I/head/d (say 50 mg/head/d) and 3-5 mg Se/head/d (say 5 mg/head/d). The calculation of T is:

   (Potassium iodide)

   T = (S . F . D . N . 100 / P ) / (1000) =

   (50 X 2 X 14 X 75 X 100 / 76.4) / (1000) = 137.4 g

   (Na selenite)

   T = (S . F . D . N . 100 / P ) / (1000) =

   (5 X 2 X 14 X 75 X 100 / 30 ) / (1000) = 35 g

   Thus, a spray of 137 g potassium iodide and 35 g Na selenite in water would be applied evenly to a well-grown sward in a plot large enough to carry 75 cows for 1-2 days. This is enough for the 75 cows, assuming that no rain falls while the cows are in the sprayed plot. The procedure would be repeated once every 2 weeks.

   Warning as regards pasture spraying: If too much spray is applied, there is a risk of poisoning stock. If too little is applied, full benefit may not be got. If the correct amount of spray is applied evenly to herbage, there is little risk of toxicity from elements such as Co, I, Mn, Zn. However, spraying with Cu or Se may be dangerous unless Cu or Se deficiency is confirmed beforehand. See also the warnings re the danger of oral Cu in sheep. Pasture spraying has the disadvantage that suckling lambs or calves may eat little grass and, thus, may get little or no supplement from sprayed grass.

    

3. Oral trace elements via the water supply to grazing cattle
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   Water medication successfully controls parasitism, bloat, hypomagnesaemia and other conditions in grazing cattle if the correct levels of additives or drugs are added to drinking water. Water intake by cattle varies by up to 15-fold between days, depending on the weather. For example, cows may drink only 5-10 l (1-2 gal) on cold, wet days but may drink 50-75 l (10-15 gal) on hot, sunny days.

   Pumps versus simple dispensers: Soluble medicaments can be added to the water in two ways: by a pump (plumbed into the mains supply) or by a simple plastic dispenser floated in the trough.

   Pumps usually maintain a fixed concentration of medicament in the water. As weather conditions vary widely between days, intake of water and the water-soluble medicament also varies by up to 15-fold between days. Therefore, pumps delivering a fixed dose/water ratio can not ensure an even intake of medicament on a day-to-day basis.

   Dispensers: Water medication, via a Ruakura-type plastic dispenser, with compounds that remain in solution has advantages over pumps and over oral free access supplements. (Dispensers are technically better than pumps. Due to wide variation in water intake between days, day-to-day variation in mineral-dose intake can be 7-14-fold, or more, from water medicated by pumps that maintain a constant dose level in water). A predetermined daily dose can be added to the water trough. This reduces day-to-day variation in mean intake of dose to almost zero, irrespective of day-to-day variation in mean water intake. Between-animal variation in dose intake in any given day is likely to be as little as 2 to 4-fold, as compared with 10 to 30-fold or more on free-access supplements.

   Inorganic trace elements in water: Up to 85% of some compounds (say Cu sulphate) precipitate in water troughs. Cattle that drink the water may get only a small fraction of the intended dose. Also, the precipitate can accumulate in the troughs, posing a risk of toxicity after some months. Thus, water medication with some inorganic trace element compounds can be dangerous.

   Water medication with chelated trace elements: Soluble chelates stay dissolved in water for long periods. They do not precipitate, as do inorganic trace elements. However, chelation may increase or decrease the absorption of the minerals by animals, depending on the chemical form of the chelate. Also, 40-90% of water drunk by cattle may by-pass the rumen, via the oesophageal groove. [Rumen by-pass of medicated water has been used to supply nutrients such as protein and B vitamins direct to the abomasum of cattle]-. Thus, water-borne minerals could be poorly utilised by cattle if the main site of absorption is in the rumen.

   Teagasc is researching a new commercial product (Flotrace) that contains chelated trace elements (Cu, Co, Se, I). A trial in drystock in 1990 gave very good results via Ruakura dispensers in the water troughs but blood samples in 1991 from dairy cows on the product gave disappointing results. The dose rate needed by cows may be higher than was provided.

   Water medication with tincture of I: If I deficiency is the only trace element deficiency on the farm, medication of water with 66 mg potassium iodide or 1 ml of tincture of I (5% I)/cow/d is effective. Amounts for other stock or sheep would be pro-rata by body weight. The daily dose should be divided in 2 or 3 parts, added 2 or 3 times/d to ensure that all stock get an even share of the dose.

   Clean troughs: To ensure that water intake remains high and to reduce the risk of chemical interaction with added medication (especially inorganic salts, such as potassium iodide or tincture of I), troughs should be cleaned out regularly.

    

4. Veterinary Products for Trace Element Supplementation
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   Effectiveness of veterinary products: Some veterinary products are excellent; others are not. Before they are used, deficiency of the specific mineral(s) should have been confirmed by blood or other tests.

   The correct dose or frequency of administration of each product must be used. If the dose is inadequate or is not given frequently enough, otherwise excellent products can give poor results. For example, because of the severity of challenge to Cu status (high Mo in feed or high soil/Fe intake), the required dose rate of Cu (or its frequency of use) in Irish herds is often 2-3 times the dose or frequency that is recommended in the United Kingdom. If excessive doses are used, there may be a risk of toxicity, especially with Cu products.

   Excellent products that supply a single trace element include: Cu-EDTA injection (100 mg Cu (subcutaneous) gives 6-12 weeks protection in cattle, but is a less preferred way to supplement with Cu) and CuO capsules (24 g CuO orally gives 2-4 months protection in cattle). Barium selenate injections (100 mg Se/100 kg LW (subcutaneous) gave disappointing results after a change of manufacturer in 1991, but gave satisfactory results in later years. [Sodium selenate or selenite injection (up to 10 mg Se/100 kg live weight, s/c) is much cheaper than barium selenate, but is short-acting. Protection lasts only 4-6 weeks. Depending on the herd-health history, frequent sodium selenate / selenite injections may be needed].

   If only one trace element deficiency (say Cu or Se deficiency) exists in a herd, effective veterinary products have advantages over oral supplements. However, some are expensive if used at the dose or frequency of administration needed in Irish herds.

   Bullets that supply 3 or more trace elements are available on the Irish market. They are given orally by a special bulleting gun. The products include "Cosecure" and the post-1991 "Alltrace". The special glass matrix of the bullets is slowly soluble in the reticulo-rumen and releases its supplement over a period of about 6-10 months. "Cosecure" and the new "Alltrace" are similar as regards control of Co, Se and Cu deficiencies. "Ionox" is a new bolus, released on the Irish market in autumn 1996. The bolus was developed in cooperation with Teagasc, Grange.

   "Cosecure" (Cooper Pitman-Moore), average weight 100 g/bullet; contains 500 mg Co, 300 mg Se and 13400 mg Cu/bullet. Three to five bullets/year would meet the Co, Se, Cu requirements of cows in severely deficient herds.

   "Alltrace" (Agrimin): In September 1991, Agrimin improved the formulation of their bullets. Each weighs 107 g and contains 240 mg Co, 245 mg Se and 16532 mg Cu. Three to five bullets/year would meet the Co, Se, Cu requirements of cows in severely Cu-deficient herds. As they are so low, its levels of other trace-elements (I, Zn etc) can be ignored.

   "Ionox" (Bayer Ireland): This cattle bolus is designed to remain in the reticulorumen during its period of trace element release; it contains 3500 mg I, 500 mg Se and 350 mg Co/bolus. Assuming linear release over a mean time of 28 weeks, mean release would be 18, 2.6 and 1.8 mg I, Se and Co/bolus/d respectively. This should be adequate for yearling cattle on pastures that pose a risk of severe deficiency of I, Se or Co. If no other I, Se or Co supplements were given, adult cows would need 2-3 boluses every 5-6 months on similar high-risk pastures.

   Multiple trace element deficiency often occurs in Irish herds. In that case, routine use of multiple veterinary products can be very expensive. Even if "Cosecure", "Alltrace" or "Ionox" bullets can be used, as 3-5 bullets/cow/year are needed under Irish conditions, oral mineral supplements may be considered as a good alternative on economic grounds. Note that Ionox contains no Cu; it is not for use as a Cu supplement.

   Poor veterinary products: Under Irish law, veterinary surgeons may prescribe any permitted product that they think fit. Most products are effective and safe if the correct dose is used in the correct circumstances. However, some are less effective than others: the manufacturer's recommended dose is too small to release the amount of required active ingredient per day to meet the animal's needs.

   Three products of questionable value in cows are: Mg bullets (to prevent hypomagnesaemia), "Alltrace" bullets (to prevent deficiency of Mn, Zn or I) and Iodine injection (to prevent I deficiency).

   Mg bullets: To give 20-40 g Mg/cow/d from Mg bullets that release 1 g Mg/d/bullet would require 20-40 bullets/cow. The usual dose of 2-4 bullets/cow is too small by a factor of 10. Mg bullets may be considered for use in suckler cows on outfarms but 4-6 bullets/cow are advisable every 4-5 weeks.

   "Alltrace" bullets: In 1991, Agrimin improved the formulation of their bullets. They now weigh 107 g/bullet and contain 0.22% Co, 0.23% Se and 15.45% Cu by weight. As discussed above, these can be considered in Cu, Se and Co deficiency, if 3-5 bullets/cow are used. Over an expected life of 8 months (240 days), the mean daily release from 4 Alltrace bullets would be 275 mg Cu, 4 mg Co and 4 mg Se. These would be useful supplements of Cu, Co and Se under Irish conditions (somewhat below the optimum values in Table 4).

   Each bullet also contains 12.7% Zn, 8.3% Mn, 0.236% I, 557000 iu Vit A, 111500 iu Vit D3 and 1115 iu Vit E but the levels of these components released from 4 Alltrace bullets are too low to be useful in seriously deficient Irish herds, as they are well below those recommended in Table 4 and Table 5. About 6-30 bullets would be needed to supply enough Zn, Mn, I, and vitamins to rectify deficiency of those elements in cows. The cost would be prohibitive and the Cu and Se release from 6-30 bullets would be too high in any case.

   Iodine injection: [Lipiodol is not registered as a veterinary therapeutic product by the National Drugs Advisory Board]. Oil-based I injections (such as Lipiodol, 40% I) sometimes are used to supply I in I-deficient herds. The oil-based products are slow-acting and we are unaware of controlled work published in refereed scientific journals that shows that they prevent neonatal problems in cows. We are also aware of failure of I injection to prevent stillbirth in calves, which was controlled within days by oral I supplements.

    

5. Soil fertilisation with trace elements
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   Why apply trace elements to soil ? The main reason for applying trace elements to soil is to try to raise the level of trace element in herbage, in an attempt to correct the economic effects of the deficiency in animals. However, soil application fails to control severe induced or secondary trace element deficiency in animals, such as that due to antagonists in the feed. Trace element fertilisation does not eliminate antagonists from the feed nor does it increase grass growth.

   Soil application may be effective in simple deficiency of Co, Se and Cu.

   In simple Co deficiency, where soil Co levels are low and soil Mn levels are normal (below 500 mg/kg), application of Co sulphate (2.24 kg/ha every 3-4 years) can raise herbage Co to normal levels. [Only 1/15^th to 1/30^th of the soil applied-Co would be effective if given directly to stock as an oral supplement (20-40 mg Co sulphate/cow/d X 365 d = 7.3-14.6 g/cow/year)].

   In simple Se deficiency, annual application of Na selenite (150 g/ha) can raise herbage Se to normal levels. Herbage Se levels above 3 mg/kg DM (the toxic level) can arise for some weeks after application. Serious over-application of Se salts can lead to Se toxicity in stock. [Only 1/8^th to 1/17^th of the soil applied-Se would be effective if given directly to stock as an oral supplement (12-24 mg Na selenite/cow/d X 365 d = 4.38-8.76 g/cow/year)].

   In simple Cu deficiency, application of Cu sulphate (22 kg/ha) can increase herbage Cu to marginal or normal levels for 7-12 years after application. As Cu hydroxide is less subject to leaching, it may last longer than Cu sulphate on sandy soils.

   Warnings: The correct amounts of trace elements must be mixed carefully in sand or fertiliser before application with a spreader or pneumatic drill. If too little is applied, the method may fail to control the animal problem. If too much is applied, there is risk of toxicity. Trace element salts should be applied to bare pasture. To limit the risk of accidental toxicity, allow time for the salts to be washed into the soil. Herbage regrowth should not be grazed for some weeks afterwards. Because of the risk of Cu toxicity, do not apply Cu to soils on sheep farms.

    

6. Periodic drenching with trace element supplements
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Simple trace element drenches and anthelmintics with added trace elements: Simple trace element drenches can be made up by veterinary surgeons or chemists. They may contain Se, I, Co and Cu, singly or in various combinations. Some commercial anthelmintic drenches also contain added trace elements, such as Co and Se. Such drenches can be used to prevent or control trace element deficiency under most circumstances in Irish flocks and herds, provided that they contain nutritionally effective levels of the required trace element(s) and are given at intervals of 2-3 weeks.

Warnings on the use of periodic drenches of trace elements: The label or accompanying leaflet on the drench should contain the following warnings:

* Shake container well between every few doses. Many drenches, especially those combining anthelmintics and trace elements, are not solutions: they are colloidal suspensions. If the container is not shaken frequently during use, de-mixing of the colloidal suspension can cause sedimentation of trace elements. The upper layer of the suspension may contain low concentrations of trace elements and the lower layer may contain toxic levels. Animals dosed from the upper layer may get too little supplement. Those drenched from the lower layer can die of acute poisoning within 1-3 days of drenching.

* Copper poisoning: Sheep, especially Island breeds (Texel, Ronaldsay, Soay breeds etc) are easily poisoned with copper. Sheep should not receive copper in drenches, mineral mixes, licks etc unless Cu deficiency has been diagnosed in the flock by a veterinary surgeon, on blood test and/or on clinical/post-mortem findings. If sheep need a Cu supplement, dosing with oral Cu oxide capsules or Cu-containing glass boluses is safer than feeding/drenching/ injecting copper compounds. For example, CuO particles in a gelatin capsule can be given at doses of 4 g (ewes), 2 g (store lambs) or 1 g (lambs 1-2 months of age). Dose once or twice/year, as needed.

Cattle can die following Cu drenches if they inhale part of the drench or if the dose is too high.

* Selenium poisoning: Se poisoning occurs in a few localised areas in Ireland, due to toxic Se levels in soil and herbage. Do not dose with Se compounds within 5 miles of known Se-toxic areas, unless Se deficiency has been diagnosed in the flock or herd by a veterinary surgeon, on blood test and/or clinical/post-mortem findings.

Formulation of a trace element drench for sheep: In practice, depending on the specific deficiencies identified on the farm, only 1-3 of the ingredients are used together and the unwanted ingredients are omitted from the formulation. (See warnings on copper and selenium above). The following can be used:

17.5 g Sodium selenite (30.0% Se) = 5.25 g Se

61.0 g Potassium iodide (76.4% I) = 46.6 g I

100.0 g Cobalt sulphate (21.0% Co) = 21.0 g Co

413.4 g Copper sulphate (25.4% Cu) = 105.0 g Cu**

Add water to 15 litres. Shake until ingredients are fully dissolved.

** Omit Cu except on veterinary advice. See Warning above.

Label for the drench: The drench should be labelled clearly, as follows:

1. Poison. For animal treatment only. Keep away from children. Use only in sheep and only as directed. See warnings on attached leaflet. Shake the drench well between every few doses.
2. Fifteen litres of Stock Solution is sufficient for 2 weeks for 750 ewes, 1071 store lambs or 2143 weaned lambs. Do not exceed the recommended dose rates. Overdosing may poison sheep.
3. When all four compounds are included, the Stock Solution contains 7 mg Cu, 3.1 mg I, 1.4 mg Co and 0.35 mg Se per ml. The fortnightly dose (20 ml/ewe) contains 140 mg Cu, 62 mg I, 28 mg Co and 7 mg Se. This is equivalent to an average daily dose of 10 mg Cu, 4.4 mg I, 2 mg Co and 0.5 mg Se per ewe. The fortnightly dose is 14 ml for stores and 7 ml for weaned lambs).
4. Drench every 2 weeks for best results in flocks at risk of Co and I deficiency. Dosing at intervals of more than 3 weeks may not control those deficiencies fully.
5. Dose:

 

Ewes	20 ml/head/2 weeks (or 30.0 ml/head/3 weeks)
Store lambs	14 ml/head/2 weeks (or 21.0 ml/head/3 weeks)
Lambs at weaning	7 ml/head/2 weeks (or 10.5 ml/head/3 weeks)

Formulation of a trace element drench for cattle: In practice, depending on the specific deficiencies identified on the farm, only 1-3 of the ingredients are used together and the unwanted ingredients are omitted from the formulation. (See warnings on copper and selenium above). The following can be used:

35.0 g Sodium selenite (30.0% Se) = 10.5 g Se

100.0 g Cobalt sulphate (21.0% Co) = 21.0 g Co

137.4 g Potassium iodide (76.4% I) = 105.0 g I

2480.3 g Copper sulphate (25.4% Cu) = 630.0 g Cu**

Add water to 30 litres. Shake until ingredients are fully dissolved.

** Omit Cu except on veterinary advice. See Warning above.

Label for the drench: The drench should be labelled clearly, as follows:

1. Poison. For animal treatment only. Keep away from children. Use only in cattle and only as directed. See warnings on attached leaflet. Shake the drench well between every few doses.
2. Thirty litres of Stock Solution is sufficient for 2 weeks for 150 cows, 300 stores or 900 weanlings. Do not exceed the recommended dose rates. Overdosing may poison stock.
3. When all four compounds are included, the Stock Solution contains 21 mg Cu, 3.5 mg I, 0.7 mg Co and 0.35 mg Se per ml. The fortnightly dose (200 ml/cow) contains 4200 mg Cu, 700 mg I, 140 mg Co and 70 mg Se. This is equivalent to an average daily dose of 300 mg Cu, 50 mg I, 10 mg Co and 5 mg Se per cow. The fortnightly dose is 200 ml for cows, 100 ml for 300 kg stores and 33 ml for 100 kg weanling calves).
4. Drench every 2 weeks for best results in herds at risk of Co and I deficiency. Dosing at intervals of more than 3 weeks may not control those deficiencies fully.
5. Dose

 

1. General warnings in connection with trace elements
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1. Products high in trace elements may be toxic. Avoid products high in trace elements, unless they are labelled clearly with instructions as to their correct use: the species, type and age of animal for which they are intended (cattle, sheep; young or adult; dry or lactating) and the daily feeding rate, for example: "Feed only to (specify dry or lactating) cows. The allowance is "X" (specify g or kg/cow/d). Do not exceed that amount".
2. Correct doses: Adhere strictly to the recommended daily allowances or dosages. Commercial concentrate rations, mineral supplements and veterinary products may give too little trace elements if used at low levels, or too much if used at high levels. Incorrect doses pose a risk of under-dosing or toxicity.
3. Iron (Fe) is a strong Cu-antagonist. Keep Fe < 2500 mg/kg in mineral mixes for cows on green feeds/roots, or omit it altogether.
4. Specific warnings: See Part (f), above, for warnings on the use of periodic drenching with trace elements. See also the specific warnings under the sections on each element below.

Summary: The main methods of routine prevention are: to control body condition at calving; to minimise Ca intake in late pregnancy; to ensure adequate Mg intake pre-calving; to minimise stress at calving; to optimise feed intake on the day of calving. If all else fails, give large doses of oral Ca +/- P supplement just before and after calving. Calcium carbonate (34% Ca) and di-calcium phosphate (22% Ca, 18% P) are common Ca salts.

Body score at calving: Control of energy intake pre-partum is essential. Feed cows so that they calve in good body condition (not too fat, not too thin). If body condition is too good, restrict energy intake and if cows/heifers are too thin, supplement energy intake.

Minimise Ca intake by cows in late pregnancy. Total intakes of 25-50 g Ca/d are ideal but are unattainable, as most common pre-partum diets of herbage or silage supply more than 55 g/cow/d. However pre-partum Ca intake can be reduced by feed restriction (if this is appropriate, considering the body condition of the cows and the quality of the forage on offer) and/or the use of low-Ca feeds (such as grains and roots). Reduced Ca intake pre-partum ensures maximal Ca absorption percentage from the digesta. If the forage has Ca > 0.4% in DM, avoid Ca supplements pre-calving, or keep them below 6 g Ca/cow/d. Pre-calver mineral mixes with 0% Ca are preferable in herds with a milk fever history. Avoid mineral mixes pre-calving if the Ca level exceeds 6%.

Mg supplements pre-calving: Inclusion of 10-20 g Mg/cow/d (say 15 g) in dry-cow supplements (about 15% Mg in mineral mixes fed pre-calving), ensures high turnover of bone Ca pre-partum.

Minimise stress at calving: Minimising stress reduces adrenalin release and fat mobilisation at calving and their adverse effects on blood Ca levels. Comfortable calving boxes and provision of shelter and warmth at calving help. Keep interference to a minimum by use of closed-circuit TV monitors and careful use of calving jacks.

Palatable feed on the day of calving: Molassed concentrates + good silage or hay enhances feed and Ca intake.

P supplements pre-calving: The most common diets of pre-partum cows are herbage and grass silage. These have ample P for dry cows. If low-P forages (such as beetpulp, fodderbeet etc) are fed, up to 20 g P/cow /d may be added. P supplements pre-calving have little effect in preventing parturient hypocalcaemia, except at impractically high levels (30-50 g P or more/cow/d).

Oral Ca +/- P on the day of calving: If parturient hypocalcaemia or milk fever occurs in spite of the methods suggested above, dosing or feeding susceptible cows with a very high Ca supplement on three occasions close to calving helps: 125 g feed-grade limestone flour (42.5-45.0 g Ca) is given 12-24h prepartum; the dose is repeated just after calving and at 12h later. If low blood P levels coexist with low blood Ca levels, 3 doses of 180 g di-calcium phosphate can be used instead of the limestone.

Ca supplements during lactation: After calving, give high yielding cows (especially those on low-Ca feeds (roots, high cereal diet)) a supplement of 7-25 g Ca/cow/d. A Ca level of the order of 0.90% is advisable in dairy concentrates fed at 7 kg/cow to high yielders. If the dairy ration has > 6% fat, it is advisable to increase Ca levels to 1.0-1.2% in the concentrate and to add Zn at high levels (750 mg Zn/cow/d).

Veterinary Products to prevent Milk Fever: Vitamin D3 injection: Injection of vitamin D3 or its synthetic analogues (cholecalciferol etc) within 8 days pre-calving was claimed to improve Ca absorption from the gut, to increase Ca mobilisation from bone to blood and to reduce the incidence of milk fever. The claims are contentious. Results are mixed; side effects may arise and milk fever may be delayed, only to arise 10 days later. The method is expensive but may be used together with the methods described above in valuable cows with a history of milk fever in previous calvings.

Summary: Co deficiency can be simple (low levels in soil and feed) or induced by high soil manganese (Mn), which prevents uptake of Co by herbage. Oral Co is the main method of correction of Co deficiency. Co sulphate (21.0% Co) is a common Co salt. Co by injection has no value.

Effective oral Co supplements: Co has no effective recycling in ruminants and no effective store exists in the body. Therefore, Co-deficient animals need Co at very frequent intervals. Co can be given in the concentrate ration or forage, in a carrier or in mineral mixes. Oral Co is usually cheaper than Co-fertilisation. See also Part 1.a, above.

Daily supplement: An oral supplement of 5-10 mg Co/cow/d can be used to rectify or prevent Co deficiency, under Irish conditions. A supplement of 5.0-7.5 mg/cow/d may suffice in mild deficiency but 7.5-10.0 mg/cow/d may be needed in severe deficiency. Table 4 shows the suggested optimum supplementation levels of Co for other classes of stock.

Co in the concentrate ration: If the concentrate is properly balanced, no other Co supplement is needed while ration is fed. See Table 6 for Co levels in dairy concentrate to provide cows with 5-10 mg Co/head/ day. If weanling cattle (250 kg) need Co supplement (2-4 mg Co/head/ day), and 1 kg concentrate is to be fed, it should contain 2-4 mg Co/kg. If ewes need Co supplement (0.5-2.0 mg Co/head/d), and 0.8 kg concentrate is to be fed, it should contain 0.63-2.5 mg Co/kg. If lambs need Co supplement (0.2-0.7 mg Co/head/d), and 0.4 kg concentrate is to be fed, it should contain 0.5-1.75 mg Co/kg.

Co in a small amount of carrier: Table 7 shows carrier formulations for cows, ewes, cattle and lambs. See Methods of Mineral Supplementation of stock (on feeding of mineral mixes and carriers).

Co in a mineral mix: Table 1 shows mineral mix formulations for cows and ewes. Table 2 shows mineral mix formulations for drystock (cattle and lambs). See Methods of Mineral Supplementation of stock (on feeding of mineral mixes).

Drenching sheep or cattle with Co: Periodic drenching with oral Co sulphate is effective if adequate doses are given often enough. A 14 to 21 day supply of Co can be given in drenches every 2-3 weeks during the grazing season. A dose of 111.1 mg Co sulphate (23.33 mg Co)/100 kg LW every 2 weeks or 166.7 mg Co sulphate (35 mg Co)/100 kg LW every 3 weeks is enough for cattle. A dose of 133.3 mg Co sulphate (28 mg Co)/70 kg LW every 2 weeks or 200 mg Co sulphate (42 mg Co)/70 kg LW every 3 weeks is enough for sheep. (For further details and warnings, see Part 1.f and Part 1.g, above).

Pasture spraying with Co Sulphate: Foliar spraying of "hospital plots" with Co sulphate (21% Co) in water every 14-21 days may be considered in simple Co deficiency and in Mn-induced Co deficiency. The basic daily supplement is about 7.93 mg Co sulphate/100 kg cattle LW or about 9.5 mg Co sulphate/70 kg sheep LW. To allow for Co falling to the ground, the basic amount of Co is doubled. A suggested dose for foliar spraying every 14 days is 222.1 mg Co sulphate/100 kg cattle LW or 266 mg Co sulphate/70 kg sheep LW. (See Part 1.b, above, for details).

Oral Co via the water supply to grazing cattle: Co can be given in chelated form in the water supply to grazing cattle (see Part 1.c, above). The daily Co supplement for cattle is shown in Table 4.

Co bullets may also be considered, especially in Co-deficient sheep. Some bullets may become coated and some may be regurgitated. For optimum results, give enough bullets to release 1-2 mg Co/d in lambs and ewes respectively.

"Cosecure" bullets (Cooper Pitman-Moore): Each cattle bullet contains 500 mg Co/bullet. In severely Co-deficient herds, 1-2 bullets per year meet the Co requirements in calves, 2 bullets per year in yearling cattle and 4 bullets per year in cows.

"Alltrace" bullets (Agrimin): Each cattle bullet contains 240 mg Co/bullet. The daily release of Co from 2 "Alltrace" bullets (2 mg Co/d) is enough for calves in severely Co deficient herds but 4-6 bullets (4-6 mg Co released/d) would be needed to control Co deficiency in cows and adult cattle.

"Ionox boluses" (Bayer Ireland): Each cattle bolus contains 350 mg Co. Mean daily Co release would be 1.8 mg Co/d respectively. This should be adequate for yearlings on pastures that pose a risk of severe deficiency of Co. If no other Co supplements were given, adult cows would need 2 boluses every 5-6 months on similar high-risk pastures.

Vitamin B12 injection: In Co deficiency, with severe anaemia or other signs in sheep or cattle, vitamin B12 injection of affected cases may save life. Then give all animals an adequate Co supplement.

Soil fertilisation with Co sulphate: Simple Co deficiency: The method is useful in simple Co deficiency. See Part 1.e, above.

Secondary Co deficiency induced by soil Mn above 500 mg/kg: Application of Co sulphate to soil is of little or no value if soil Co is normal to low and soil Mn is high. In that case, if there are signs of Co deficiency with decreased animal productivity, supplementary Co must be given directly (orally) to the affected groups of animals.

Summary: Cu deficiency can be simple (low levels in soil and feed) or induced by high levels of Cu-antagonists in the diet (Mo, soil, Fe, factors in lush grass, S in sheep). Use of veterinary Cu products and oral Cu are the main method of correction of Cu deficiency. Cu sulphate (25.4% Cu) is a common Cu salt. One may use pasture management to reduce the intake of Cu-antagonists also. In simple Cu deficiency, soil application of Cu may be considered.

Warning: Some breeds of sheep are easily poisoned with Cu. Give oral Cu to sheep only on specific veterinary advice. Cu sulphate drench, if it accidentally enters the lungs, can cause shock and death in cattle as well as sheep.

Effective oral Cu supplements: Cu can be given in the concentrate ration or forage, in a carrier or in mineral mixes. See also Part 1.a, above.

Daily supplement: An oral supplement of 150-450 mg Cu/cow/d can be used to rectify or prevent Cu deficiency, under Irish conditions: 150-300 mg Cu/cow/d may suffice in mild deficiency but 300-450 mg Cu/cow/d (and, occasionally more) may be needed in severe deficiency, such as in high Mo areas. Table 4 shows the suggested optimum supplementation levels of Cu for other classes of stock.

Cu in the concentrate ration: If the concentrate ration is properly balanced, no other Cu supplement is needed while ration is fed. See Table 6 for Cu levels in dairy concentrate to provide cows with 150-450 mg Cu/head/d. If weanling cattle (250 kg) need Cu supplement (68-182 mg Cu/head/d), and 1 kg concentrate is to be fed, it should contain 68-182 mg Cu/kg. If ewes need Cu supplement (0-18 mg Cu/head/ day), and 0.8 kg concentrate is to be fed, it should contain 0-22.5 mg Cu/kg. If lambs need Cu supplement (0-14 mg Cu/head/d), and 0.4 kg concentrate is to be fed, it should contain 0-35 mg Cu/kg.

Cu in a small amount of carrier: Table 7 shows carrier formulations for cows, ewes, cattle and lambs. See Methods of Mineral Supplementation of stock (on feeding of mineral mixes and carriers).

Cu in a mineral mix: Table 1 shows mineral mix formulations for cows and ewes. Table 2 shows mineral mix formulations for drystock (cattle and lambs). See Methods of Mineral Supplementation of stock (on feeding of mineral mixes).

Drenching sheep or cattle with Cu: Periodic drenching with oral Cu sulphate may be considered if adequate doses are given often enough. A 14 to 21 day supply of Cu can be given in drenches every 2-3 weeks during the grazing season. A dose of 2.8 g Cu sulphate (700 mg Cu)/100 kg LW every 2 weeks or 4.2 g Cu sulphate (1050 mg Cu)/100 kg LW every 3 weeks is enough for cattle. A dose of 560 mg Cu sulphate (140 mg Cu)/70 kg LW every 2 weeks or 840 mg Cu sulphate (210 mg Cu)/70 kg LW every 3 weeks is enough for sheep. For further details and warnings, see Part 1.f and Part 1.g, above.

Pasture spraying with Cu sulphate: Foliar spraying of "hospital plots" with Cu sulphate in water every 14-21 days may be considered in simple and induced Cu deficiency. The basic daily supplement is about 196.8 mg Cu sulphate/100 kg cattle LW or about 39.4 mg Cu sulphate/70 kg sheep LW. To allow for Cu falling to the ground, the basic amount of Cu is doubled. A suggested dose for foliar spraying every 14 days is 5.5 g Cu sulphate/100 kg cattle LW or 1.1 g Cu sulphate/70 kg sheep LW. (See Part 1.b, above, for details).

Warning: Do not use this method for sheep except under veterinary advice

Oral Cu via the water supply to grazing cattle: Cu can be given in chelated form in the water supply to grazing cattle (see Part 1.c, above). The daily Cu supplement is shown in Table 4.

Veterinary products for Cu Supplementation: Veterinary Cu supplements include injections, boluses and bullets containing Cu compounds. Because Mo challenge is high in Ireland, the annual Cu dose needed to control diagnosed Cu deficiency is greater than is the case in the U.K. For general discussion of timing of administration of Cu compounds, see Mineral Storage in the Body and Timing of Administration of Supplements.

Cu treatment of calves: Suckler calves in Cu-deficient herds may show illthrift by 3-4 months of age. In such herds, treatment of the dam in late pregnancy and of the calves from 1 month of age may be needed. Bucket-reared calves usually have a much higher Cu status at birth and at 2-3 months of age than that of suckler calves. They seldom need Cu-treatment before 6-9 months of age.

Cu treatment of lambs: Lambs in Cu-deficient flocks may show illthrift pre-weaning, but especially post-weaning. In such flocks, treatment of the dam in late pregnancy and of the lambs from 1 month of age may be needed. Cu oxide capsules are the safest treatment (see next page).

Dosage and frequency of administration of Cu compounds depends on the weight of the animals and on the degree of challenge to Cu status. Heavier animals need larger doses. More frequent doses are needed in groups exposed to high challenge, such as on high-Mo farms. (See footnote 9).

Cu injections: There are many injectable Cu compounds. Intramuscular injections are not recommended, as they may damage meat. Avoid Cu injections within 4-6 weeks before mating and during the breeding season, as the pain/swellings may reduce conception rates. (Cu bullets, boluses or oral Cu supplements are preferable during the mating period).

Cu-EDTA (sub-cutaneous) is very effective. [Other Cu compounds may be used instead, but Cu-EDTA is the most widely used form of injectable Cu. It gives very good results in normalising Cu status, but has disadvantages that render it undesirable for routine use in the national herd]. Cu-deficient suckler calves 50-100 kg LW are usually given 50 mg Cu. The dose for cattle is 100 mg Cu, repeated as needed. In Irish cattle, one shot lasts 6-12 weeks, depending on the challenge to Cu status. On high-Mo farms, young-stock and yearlings may need 3-4 shots per year. In marginal deficiency, 2 shots/year may suffice. The number of shots per cow depends on the clinical problems in the cows. If abortions, stillbirths and infertility are due to Cu deficiency, at least three shots are needed: one in mid pregnancy, one about 5 weeks before calving and one very soon after calving. (The pregnant cow shunts most of the injected Cu to the foetus and may have little in her reserve depot (liver) after calving).

Warnings regarding Cu injections: All Cu-injections are irritant. If possible, avoid the use of Cu injections in animals destined for slaughter, as abscesses and scarring of tissues can follow injection. Avoid especially Cu-EDTA or other irritant injections during or less than 1 month before the breeding season. Local reaction to irritant compounds may depress conception rates by up to 20 points. If Cu is needed, oral CuO capsules or other oral Cu supplements are preferable at this time. Use Cu injections in sheep only on specific veterinary advice. High mortality from Cu poisoning may occur within days after injection of Cu compounds in sheep.

Cu oxide capsules or boluses are the preferred veterinary product for use as a copper supplement for cattle and sheep. These gelatin capsules contain Cu oxide particles. They are given orally with a special bulleting-gun. Optimum doses for Irish cattle in moderately deficient herds are 8 g Cu oxide/100 kg LW annually. Longer protection can be got from 2 doses/year at 4 g/100 kg LW each time than from the whole dose given at one time. In severely deficient herds, especially on high-Mo farms, 16-20 g Cu oxide/100 kg LW annually may be needed. Longer protection can be got from 4-5 doses/year at 4 g/100 kg LW each time than from the whole dose given at one time. CuO capsules can be used safely during the breeding season, whereas Cu-EDTA injection can depress conception rates.

Treatment with CuO capsules is the safest way to supplement sheep with Cu. The dose of CuO is: ewes 4 g; weaned lambs 2 g; young lambs 1 g. The dose may have to be repeated every 4-6 months, especially if the challenge to Cu status is severe.

Cu bullets: Glass bullets that supply Cu are available ("Alltrace" and "Cosecure