Mineral Supplementation of Dairy
Cows:
An In-Service Training Seminar for
Teagasc Advisers
by Phil
Rogers MRCVS, Teagasc, Grange
Introduction
This file is on WWW at http://homepage.eircom.net/~progers/tahip/dairy_min.doc and should be read in conjunction with references (2 and 3).
Table 1 shows the mean mineral levels in Irish forages (pasture and grass silage) in the early 1990s (1). Values highlighted in yellow indicate abnormal national means for that element.
Table 1: Mean mineral levels in Irish forages (pasture and
grass silage) in the early 1990s.
|
Major elements (% DM) |
Forage |
|
Ca |
P |
K |
Mg |
N |
Na |
S |
|
Pasture |
Mean |
0.65 |
0.40 |
2.83 |
0.20 |
3.51 |
0.29 |
0.39 |
|
|
SD* |
0.18 |
0.09 |
0.76 |
0.05 |
0.96 |
0.17 |
0.10 |
|
|
|
|
|
|
|
|
|
|
|
Silage |
Mean |
0.69 |
0.31 |
2.35 |
0.18 |
2.41 |
0.36 |
0.31 |
|
|
SD* |
0.16 |
0.07 |
0.62 |
0.04 |
0.56 |
0.15 |
0.11 |
|
|
Trace elements (mg/kg DM) |
Forage |
|
Cu |
Mo |
Se |
I |
Zn |
Mn |
|
Pasture |
Mean |
9.22 |
2.49 |
0.09 |
0.26 |
30.8 |
119.8 |
|
|
SD* |
2.67 |
3.09 |
0.15 |
0.18 |
8.7 |
97.0 |
|
|
|
|
|
|
|
|
|
|
Silage |
Mean |
10.36 |
1.48 |
0.09 |
0.27 |
29.7 |
103.5 |
|
|
SD* |
5.26 |
1.17 |
0.13 |
0.18 |
10.5 |
60.1 |
|
*SD (standard deviation): 95% of values fall in the range (mean +/- SD*1), i.e. 95% of Irish herbage Ca values lay between 0.47 and 0.83 %DM; 99% of values fall in the range (mean +/- SD*2), i.e. 99% of Irish herbage Ca values lay between 0.29 and 1.01 %DM.
The main imbalances found in Irish pasture
(1) were:
From these national data, it follows
that optimal mineral nutrition of Irish cattle and sheep on forage-based diets
involves routine supplementation to ensure balanced inputs of the essential
major- and trace- elements to ensure that neither deficiencies (primary or
secondary) nor toxicities occur.
For details on the methods of
control of mineral imbalances in cattle, see the REFERENCES at
the end of this paper, especially references (2 and 3).
1. FUNCTIONS OF THE ESSENTIAL MAJOR ELEMENTS
In this section, the clinical signs
of mineral deficiency and toxicity were taken from WWW, and especially from Dr.
Maurice E White’s “Cornell Consultant
(4), adapted for
conditions seen in
Calcium (Ca)
is the most common mineral in the body; 99% of it is in bones and teeth; the
other 1% is in the blood and soft tissue. Adequate dietary Ca is critical to
maintain a healthy skeleton and teeth. Ca also is necessary for:
o
neuromuscular transmission smooth and skeletal muscle
contraction
o
cardiac automaticity
o
constriction and relaxation of blood vessels
o
nerve function
o
cell division and movement
o
cellular oxidative processes
o
signal for secretion of hormones, such as insulin
o
co-factor for "vitamin K-dependent" clotting
factors in blood coagulation (needed to protect against fatal blood-loss after
calving, wounds, surgery, etc)
o
Intracellular calcium is a second messenger in many
intracellular responses to chemical and electrical stimuli and required by many
enzymes for full activity
o
Many different calcium binding proteins have been described;
two with well established functions are troponin and calmodulin. Troponin is
involved in muscle contraction; calmodulin causes configurational changes to
proteins and enzyme activation.
Ca levels
in the blood and fluid surrounding the cells (extracellular fluid) must be kept
within a narrow concentration range for normal physiological functioning. The
physiological functions of calcium are so vital to survival that when calcium
intake is inadequate the body demineralises bone to maintain normal blood
calcium levels.
Hypocalcaemia (low blood Ca
status) may cause milk fever: ataxia, muscle weakness, ruminal stasis
(hypomotility or atony), downer cow (inability
to stand), coma, circulatory
shock and death. Other signs of hypocalcaemia include: abdominal distension, abnormal
anal, perineal, tail reflexes, abnormal
pupillary response to light, agalactia,
anorexia, arrhythmia, ataxia, atrial
fibrillation, bloat, cold skin, decreased amount or absent faeces, constipation, diarrhoea, dullness, dysmetria,
dyspnoea, dystocia, excitement, fever, generalized weakness, grinding teeth, hyperesthesia, hypothermia, inability
to open (trismus) and/or close jaw, increased
respiratory rate, muffled,
decreased, heart sounds, mydriasis,
pulse deficiency, seizures or syncope, sinus tachycardia, tachycardia, tetany, tetraparesis,
tongue protrusion, trembling, tremor and weak
pulse.
Hypocalcaemia,
even in the absence of milk fever, can weaken the contractions of the uterus at
parturition. This may prolong calving and may cause dystocia, stillbirth, weak
calves and retained placenta and metritis. Thus, hypocalcaemia, with or without
Mg deficiency can influence fertility indirectly via its effect on the uterus
and consequent metritis.
For
details on the control of parturient hypocalcaemia and milk fever, see references (5 and 6) and http://homepage.eircom.net/~progers/tahip/3control.htm#hypocal
Ca excess is rare in ruminants because they can handle huge amounts of dietary Ca by shutting down its absorption. However, cows can die during treatment for milk fever if Ca borogluconate is injected too rapidly intravenously.
Phosphorus (P) is the second most common mineral in the body; 85% of it is in teeth and
bone; the other 15% is in body fluids and in the genetic material in cells.
Adequate dietary P is critical to maintain a healthy skeleton and teeth. P also
is necessary to:
Hypophosphataemia (low
blood P status) in cattle may cause: abnormal length oestrus cycle, agalactia, anoestrus,
anorexia, dryness of skin or hair, female infertility, forelimb lameness, forelimb swelling, generalized lameness or stiffness, hindlimb lameness, hindlimb swelling, inability to stand, lack of growth or weight gain, pica, reluctant to move, rough
hair coat, underweight, poor
condition, thin, emaciated, unthriftiness, ill thrift and weight loss.
In
Excess P is undesirable; it reduces the
absorption of Ca and Mg. In calves, it can cause urinary stones that may
obstruct male calves and require surgery.
Magnesium (Mg): Adequate dietary Mg is critical to prevent grass tetany and milk fever
and for optimal dry matter intake and milk yield in dairy cows. Mg also is
necessary:
Hypomagnesaemia (low blood Mg status) may cause grass tetany (tremors,
spasms, convulsions, ataxia, muscle weakness, recumbency and death; death may
be sudden); reduced feed intake and lower milk yield in dairy cows; softening
and weakening of bone, with increased risk of parturient hypocalcaemia and milk
fever in cows; heart arrhythmia, irregular contraction, or increased heart
rate; hypertension; imbalanced blood sugar levels; headaches. Other signs of
hypomagnesaemia in cattle include: abnormal
behaviour, aggression, changing habits, anorexia,
change in voice, cold skin, coma, constant or
increased bawling, dullness, dysmetria, dyspnoea, excessive
salivation, excitement, fever, generalized lameness or stiffness, generalized weakness, grinding
teeth, head pressing, hyperesthesia, inability to stand, increased
frequency of urination, increased
respiratory rate, nystagmus, opisthotonus, prolapsed third eyelid, propulsion,
seizures or syncope, sudden death, tachycardia, tetraparesis,
vomiting or regurgitation.
For details on the control
of hypomagnesaemia and grass tetany, see reference (7) and http://homepage.eircom.net/~progers/tahip/3control.htm#conmg
Excess Mg is undesirable; it causes anorexia, cold skin, diarrhoea, reduced milk yield, dullness, generalized weakness, hypothermia, inability to stand and tetraparesis. In calves, it can cause urinary stones that may obstruct male calves and require surgery. Also, cows can die during treatment for milk fever or grass tetany if Mg salts (usually magnesium sulphate) is injected too rapidly intravenously.
Sodium (Na):
Adequate dietary Na is critical to maintain normal fluid and electrolyte
balance in blood and cells and. Na (as salt) also is essential:
Na (or salt) deficiency in ruminants may cause agalactia, anorexia, decreased or absent thirst, hypodipsia, adipsia, lack of growth or weight gain, oliguria or anuria, pica, polydipsia, polyuria, underweight, poor condition, thin, emaciated, unthriftiness, ill thrift and weight loss. For details on the control of Na deficiency in cattle, see http://homepage.eircom.net/~progers/tahip/3control.htm#conna
Excess Na (or salt) is undesirable; it causes dehydration and may trigger hypertension; gross excess (especially if water intake is restricted) may poison stock. Salt toxicity and water intoxication in ruminants may cause: abdominal distension, anorexia, arrhythmia, ataxia, blindness, bloat in ruminants, colic, coma, diarrhoea, dullness, dyspnoea, excessive salivation, excitement, fever, generalized weakness, haemoglobinuria or myoglobinuria, haemoptysis coughing up blood, hyperesthesia, hypothermia, inability to stand, increased frequency of urination, increased respiratory rate, nystagmus, oliguria or anuria, opisthotonus, pale, polydipsia, polyuria, red or brown urine, seizures or syncope, stiffness or extended neck, sudden death, tachycardia, trembling and tremor.
2. FUNCTIONS OF THE ESSENTIAL TRACE ELEMENTS
Copper (Cu):
About 33% of total body copper is in skeletal muscle, 33% in brain and liver
and 33% in bone and other tissues. As bile is the main excretion route for Cu,
liver and gallbladder diseases may affect copper balance.
Cu is part of prolyl and lysyl
hydoxylases, enzymes needed for collagen synthesis. Because of this, connective
tissue-rich tissues such as capillaries, scar tissue, and bone matrix are most
sensitive to copper status. Copper also functions at the catalytic site of the
antioxidant enzyme superoxide dismutase (SOD). Also, the copper-containing
plasma protein caeruloplasmin is integral to iron
metabolism since it catalyzes oxidation of the mineral, which is required for
its binding to proteins involved in absorption, transport, and storage. The redox potential of copper ions gives it a key role in
energy metabolism as a component of the cytochromes
that participate in electron transport.
Cu,
molybdenum
(Mo), sulphur (S), iron (Fe) and lush grass: All of these are inter-related in cow nutrition. Cu
antagonists in the feed interfere with absorption and/or utilisation of
Hypocuprosis
(clinical Cu deficiency) in stock, especially that induced by high Mo levels or
other antagonists in feed, can cause loss of productivity and ill-health. While
calves and yearling cattle are particularly susceptible, cows, adult cattle,
sheep and lambs can be affected also. Induced deficiency is more common and
much more important economically than simple Cu deficiency. Cu deficiency may
cause skeletal abnormalities, reproductive difficulties, impaired nervous
tissue function and changes in hair and skin pigmentation. Cu also helps to
maintain bone mass.
Normal levels of dietary Cu for
cattle are 10-30 mg/kg DM. Levels of Cu in herbage >10 mg/kg DM are rarely
attained, especially in pure ryegrass swards. Old pastures which contain
clovers, herbs and weeds usually have higher levels of Cu than pure ryegrass
but overall do not compare with them in stock carrying capacity. Feed Cu levels
of 7.0-9.9 mg/kg DM are marginal for cattle, 5.0-6.9 are low and <5 mg/kg DM
are very deficient in the absence of Cu supplements. Although simple Cu
deficiency occurs in
Sheep need less feed Cu than cattle. In the absence of Cu-antagonists, Cu levels of 7-15 mg/kg DM are optimal. Levels >15 mg/kg DM may poison sheep and <7 mg/kg DM are deficient.
Dietary Mo
levels:
Mo toxicity: Dietary Mo levels >10 mg/kg DM may be toxic, depending on Cu intake in feed or supplements. Signs may include early embryonic death (day 6 to day 14) with return to oestrus in 18-24 days. Anoestrus or suboestrus may occur. Abortion, stillbirth, lowered immunity, death in young calves, severe scouring, faded coats, stiffness, lameness, poor thrive in growing cattle can arise also. Severe scouring, ill thrift, lowered milk yield, emaciation and death, even in cows, can arise in very severe cases.
Cu/Mo ratio: A Cu/Mo ratio in the diet of at least 3/1 is needed to prevent Cu deficiency and to avoid Mo toxicity. A ratio of at least 4/1 may be necessary to prevent low blood Cu levels in sheep. Cu/Mo ratios <2/1 are low and <1.5/1 are very low. Low Cu/Mo ratios can cause severe Cu deficiency in the absence of Cu supplements.
Liming: Liming decreases Cu, Co, I and Mn levels in herbage but increases the levels of Mo and Se.
Lush grass and
fertilisers:
Cu deficiency can
arise on feeds with Cu >10 mg/kg DM and Mo <2 mg/kg DM. For example, N,
P, K fertilisers influence Cu status in herbage and animals. Application of N,
especially when combined with P and K, can produce lush grass (high N, P, and K).
This can reduce transit time of feed in the digestive tract and cause digestive
upset/grass scours. Thus, factors in lush grass may reduce the absorption of
minerals, including Cu and Mg. Feed tests for N, P, and K can suggest high
intakes of these elements. Lush or rapidly growing grass (N >3.0% DM; K
>3.0% DM; P >0.4% DM) has a laxative effect and may reduce the rate of
absorption of some minerals, including Cu.
Also, the effect of N fertiliser has paradoxical effects on Cu levels in herbage. The effect depends on the initial soil Cu status. If soil Cu levels are high, N raises the herbage Cu content but if soil Cu levels are low, N reduces herbage Cu levels.
Dietary Cu and S: In other countries, high intake of S in feed (feed S >0.30 and especially >0.40% DM) or of sulphate ion from deep-bore water has exaggerated Cu deficiency. Feed tests for S may be useful to explain Cu deficiency in cases that arise in the absence of other obvious causes. As mentioned under feed S levels above, ideal S levels are 0.16-0.30% DM. Feed S levels >0.30% may induce Cu deficiency in sheep or increase their requirement for dietary Cu. Under Irish conditions, sulphate ion, such as in sulphuric acid additive with no added Cu, can depress Cu status in cattle but high S levels in herbage, or feeding flowers of S for long periods have little effect on Cu status in cattle.
For details on the prevalence and
control of Cu deficiency in cattle, see references (8) and http://homepage.eircom.net/~progers/tahip/3control.htm#cudef
Cu toxicity: Excessive
Cu inputs easily poison sheep and pre-ruminant calves. Although adult cattle tolerate
high Cu inputs, cases of Cu toxicity have occurred in cows in
Selenium (Se): Se functions in 4 main areas: antioxidant function, immunocompetence,
prostaglandin synthesis and deiodination in the thyroid gland.
In most other countries, a selenium (Se) intake of 0.10-0.18 mg/kg DM in total feed (depending on vitamin E content) is recommended to maintain Se levels in blood above the minimum normal level. Our cattle seem to need higher Se levels in feed, at least 0.24 mg/kg DM, to maintain normal Se status in blood. The discrepancy between our results and those of other countries is under investigation. EEC legislation allows a total feed Se level up to 0.50 mg/kg DM.
Se deficiency: Se deficiency on blood test (herd mean GPx levels <42iu/g Hb) is widespread in Irish cattle. Se deficiency in sheep (flock mean GPx levels <84iu/g Hb) occurs less often than in cattle. Most of these herds and flocks are (probably) in the non-clinical and sub-clinical categories.
Clinical signs
of Se deficiency include late
abortion/stillbirth/weak calves or lambs with enlarged thyroids, retained
placenta, low immunity to infection in all ages of cattle and reduced fertility
in bulls. Se deficiency may also cause muscular stiffness, recumbency,
difficult breathing and poor weight gains in younger cattle. Early embryonic
death (day 6 to 14) may occur, with return to oestrus in 18-24 days. Anoestrus
or suboestrus may occur.
Clinical signs usually do not arise unless blood Se is near or <50% of normal blood Se levels but sub-clinical signs and lowered herd immunity to infection may arise at higher levels. Decreased immunity in animals is linked with deficiency of Se, Cu, Co, Zn, I and vitamins (especially Vits A and E). Lowered resistance to disease may increase somatic cell counts and the incidence of mastitis and metritis. Increased incidence of pneumonia, scours and joint-ill may increase mortality in calves and lambs.
Se-responsive disorders may arise if feed Se or herd mean blood GPx falls <67% of the lower limit of the normal range. Marginal Se deficiency on blood or feed test seldom cause loss of productivity but may be involved in lowered immune status.
Differential diagnosis of Se and I deficiency in perinatal problems: Very low Se status in animals can interfere with thyroid function and I metabolism. Blood tests for GPx and plasma I can be used to check this. A differential diagnosis between Se deficiency and iodine (I) deficiency must be made because either deficiency may cause abortion/stillbirth/weak calves with enlarged thyroids.
Se and vitamin E: Dietary intake of vitamin E may influence the effects of Se deficiency in ruminants or the effects of Se deficiency may be independent of Vit E. Clinical and/or subclinical signs of Se deficiency often occur at pasture (rich in Vit E) or on silage (in which some Vit E may be destroyed). For details on the prevalence and control of Se deficiency in cattle, see references (8) and http://homepage.eircom.net/~progers/tahip/3control.htm#conse
Se toxicity: In selenium-toxic Irish pastures, herbage Se averages 18 mg/kg DM (range 1.6-140 mg/kg DM, with a few values above this; 50% of values are >6 mg/kg DM and 90% >3 mg/kg DM). Feed Se levels >3 mg/kg DM have been recorded also without adverse effect on stock.
Clinical signs
of Se toxicity include severe lameness, horizontal
grooves, cracks and sloughing of hooves, loss of appetite, loss of hair from
the tail and eventually, death. High-Se pastures occur in
For details on Se toxicity, and for methods of
control, see references (9)
and http://homepage.eircom.net/~progers/tahip/3control.htm#setox
Iodine (I):
The thyroid needs adequate amounts of I for synthesis of thyroxine (T4)
and triiodothyronine (T3), hormones that regulate energy metabolism,
growth, development, lactation, and reproduction.. The thyroid gland stores
about 60% of the body’s I pool. The rest is in the blood, ovary, and muscle.
I deficiency: 97% of
Irish forages are subnormal in iodine and common feedstuffs (high-nitrate
grass, clovers, brassicas, soyabean, etc) contain goitrogenic factors. Though non-clinical
I deficiency is common, herds that do not receive an I supplement are at risk
of developing clinical or subclinical signs of I deficiency.
Goitre is a non-inflammatory, non-cancerous
thyroid enlargement, often caused by direct I deficiency, or due to plants
which interfere with iodine metabolism, such as brassicas (kale, rape or
turnips, mustards, etc), soybeans and peanuts. Thyroid enlargement is most
common in young animals but can also occur in older stock. It is more common in
endemic areas, especially in mountains, on peaty soils and on high-Ca soils.
Heavy liming can precipitate goitre in stock if I supplements are not provided.
Goitre also can arise in I toxicity, and in Se deficiency.
Textbook
Signs of goitre in ruminants include: abnormal breathing sounds of the
upper airway (due to the swollen thyroid pressing on the airway), abnormal length of oestrous cycle, abortion or weak newborns, alopecia, dryness of skin or hair, female
infertility, generalized
weakness, hyperkeratosis, lack of growth or weight gain, lack of libido or erection, laryngeal, tracheal, pharyngeal
swelling, male infertility, neck swelling, skin scales, underweight,
poor condition, thin, emaciated, unthriftiness, ill thrift, weight loss
Common signs of bovine I deficiency
in Ireland include: infertility (anoestrus or repeat
breeding), abortion, stillbirth, weak-calf syndrome (calf born alive but weak,
slow to suck and high mortality in the first few days of life), lazy calving
and retained placenta.
I (like
Cu, Se, Co, Zn and Vit E) is important for a competent immune system in calves
and cows. I deficiency renders a herd more prone to bacterial and protozoal
infection, including calf scours, pneumonia, metritis and mastitis.
Though
severe I deficiency can reduce milk yield and growth rate, these effects are
uncommon in
I toxicity can arise
if grossly excessive I supplements are used. It can cause: agalactia, anorexia, chemosis
(exophthalmos, swelling and
redness of conjunctival &
scleral membranes of the eyelids and eye surface, coughing, dryness
of skin or hair, excessive
salivation, female infertility, fever, increased respiratory rate, lack of growth or weight gain, lacrimation, mucoid
nasal discharge, rough hair
coat, skin crusts and scales.
Severe toxicity can cause abortion or stillbirth of calves with a toxic goitre.
Cobalt (Co): Co
is part of cobalamin (Vit B12). Cattle do not need a dietary source
of vitamin B12 because ruminal microorganisms synthesize B12
from dietary
(a) Primary Co deficiency in soil and herbage occurs especially on
peaty soils, calcareous soils derived from sea-shells and soils derived from
granite and sandstone rocks (most of the mountainous areas of
(b) Secondary Co deficiency occurs on soils with adequate Co but high
manganese (Mn). High soil Mn blocks herbage uptake of Co from soil. Mn-induced
deficiency is very common in limestone soils that stretch from counties Meath
and
Common signs of bovine Co deficiency: Co deficiency often is non-clinical
but may cause subclinical and clinical signs in sheep and cattle (more often in
sheep). Effects in cattle (especially in calves on peaty soils) include reduced
feed intake, poor appetite or anorexia,
poor condition, poor thrive or decreased growth, emaciation, rough appearance (rough hair coat) and a markedly
reduced vitamin B12 status in serum and liver.
Other signs include: agalactia, anaemia or pale mucosae, rapid heart rate, female
infertility, anoestrus, diarrhoea, dullness, exercise
intolerance, generalized
weakness and pica.
Co (like
Cu, Se, I, Zn and Vit E) is important for a competent immune system in calves
and cows. Co deficiency renders a herd more prone to roundworm infestation,
especially ostertagiasis.
For details on the control of Co deficiency in cattle, see reference http://homepage.eircom.net/~progers/tahip/3control.htm#codef
Co toxicity in cattle and sheep: On farms where Co deficiency
occurs, it is common to supplement ruminants with Co at 5-10mg Co/d (adult
cattle) or 1-2mg Co/d (adult sheep). Gross overdosing can kill. The lethal dose
is extremely high, about 6.6-22mg/kg LW in cattle and 44-66mg/kg LW in sheep.
Diagnosis is by dietary history and liver and kidney cobalt levels.
Clinical signs of Co toxicity include: agalactia,
anorexia, dullness, inability to stand, polydipsia,
polyuria, sudden death, underweight, poor condition, thin, emaciated, unthriftiness, ill
thrift, weight loss.
Zinc (Zn): Zn is a cofactor for >100 enzymes in the body. Zn-dependent
enzymes are needed to metabolise protein, nucleic acid, carbohydrate, fat and
alcohol. Zn is important for normal immune system development and function. Zn
also is essential for protein synthesis, integrity of cell membranes, skin and
hoof health, maintenance of DNA and RNA, tissue growth and repair, wound
healing, taste acuity, prostaglandin production, bone mineralization, proper
thyroid function, blood clotting and cognitive functions. Considering its role
in growth and development, Zn is an integral mineral for foetal development and
sperm production.
Two forms of Zn deficiency occur: (a) Primary Zn
deficiency is uncommon in Irish ruminants, even though 25% of Irish forages
have subnormal Zn levels (Table 1). (b)
Secondary Zn deficiency (due to excessive intake of Ca) occurs
occasionally. Cattle on high-Ca feeds should receive a generous Zn supplement
(750mg Zn/cow/d).
Clinical signs of Zn Deficiency
include: small testes/scrotum, alopecia, anestrus, anorexia, cracked skin, decreased
mobility of forelimb joint, defective
growth of nail, claw, hoof; dryness
of skin or hair, dullness, excessive salivation, female infertility, forefoot pain, forelimb swelling, foot lameness, generalized weakness, hindfoot pain, hindlimb
swelling, hyperkeratosis, inability to stand, kyphosis, lack of growth or weight gain, lack of libido or erection, lacrimation, male infertility, matted
or dirty hair, oily skin, hair
or feathers, greasy, opisthotonus,
pale mucosae, parakeratosis (thickened skin), pica, pruritus, rough hair coat, skin crusts, skin erythema, skin pain, skin
scales, skin ulcer, splitting nail, claw, hoof, tachycardia, trembling, underweight,
poor condition, thin, emaciated, unthriftiness, ill thrift and weight loss.
Skin lesions of Zn deficiency have
been produced experimentally and suspected clinically when there was low Zn in
the diet associated with high Ca. Horn growth can be inhibited. Clinical
disease is uncommonly recognized in the field. Blood samples for Zn levels can
easily be contaminated by needles, bottles or rubber stoppers. For details on
the control of Zn deficiency in cattle, see reference http://homepage.eircom.net/~progers/tahip/3control.htm#conzn
“Protected
Zn” versus Inorganic Zn?: Although anecdotal, and without a firm
scientific basis, some Irish farmers reported that outbreaks of hoof-lameness
in their cows that failed to respond to inorganic Zn supplements (usually Zn
sulphate) cleared up within weeks of including “protected Zn” supplement,
usually Zn-methionine. For more details on causes and control of lameness in
cows, see reference (12).
Lethal
Trait A 46, Parakeratosis, Zn Deficiency in Calves is a rare, progressive and sometimes
fatal disease of calves characterized by oozing and crusting lesions associated
with hair loss, especially of the lower limbs, head, and neck. There can be
associated delayed wound healing and pneumonia. The condition is due to an autosomal recessive gene causing an excessive Zn requirement
due to an inability to efficiently absorb Zn from the gastrointestinal tract.
Onset of signs is at 2-6 weeks of age, with diarrhea
usually the earliest clinical sign. Affected calves may have diminished
suckling ability; difficulty in curving their tongues around the nipple causes
a chewing and pulling motion with their tongues flat against the nipple to
ingest milk. A 'spectacled' appearance, like that seen in Cu deficiency, can
occur. The condition is reported in Friesian, Danish Black Pied, Angus, and
Shorthorn breeds. Clinical signs
include: abnormal lung or
pleural sounds, absence of skin,
alopecia, anorexia, chemosis, congestion
oral mucous membranes, conjunctival,
scleral, injection, conjunctival,
scleral, redness, corneal edema, coughing,
cracked skin, decreased hair pigment, diarrhea, dryness of skin or hair, dullness, dyspnea, excessive salivation, fever, hyperkeratosis, increased
respiratory rate, lack of growth
or weight gain, lacrimation, moist skin, hair or feathers, mucoid nasal discharge, oily skin, hair or feathers, greasy, oral mucosal ulcers, vesicles, pruritus, purulent nasal discharge, rough hair coat, skin crusts, skin erythema, skin pain, skin
scales, tongue ulcers, vesicles,
underweight, poor condition,
thin, emaciated, unthriftiness, ill thrift and weight loss.
Zn toxicity from
excessive amounts of Zn in animal feeds or minerals is very rare in
However,
cattle in
Clinical signs of Zn oxide toxicity
include: agalactia, anorexia, cold
skin, dehydration, diarrhea, generalized weakness, inability to stand, tachycardia, tetraparesis and weak
pulse.
Also, several
incidents of Zn toxicity in cattle and sheep occurred in
Manganese (Mn): Mn is part of the enzymes pyruvate carboxylase, arginase and superoxide
dismutase (SOD). It also activates hydrolases, kinases, transferases and decarboxylases.
Of the many enzymes activated by Mn, only glycosyltransferases are known to
require it specifically.
Mn requirements for reproduction are
higher than for growth and skeletal development. The recommended concentration
for breeding cattle is 40 mg/kg DM.
Mn deficiency in early pregnancy has caused a few
outbreaks of chondrodystrophy, a congenital developmental defect. Affected
calves are born dead, or born as dwarfs with domed heads, cleft palate,
abnormal limbs, etc. It also can cause abortion
or weak newborns, anoestrus, female infertility, and male infertility. Other signs include:
abortion or weak newborns, anestrus, female infertility, male infertility, small litter size (pigs and sheep).
Fortunately, though described, Mn
deficiency is rare in
3. SUPPLEMENTATION RATES FOR THE MAJOR ELEMENTS AND TRACE ELEMENTS Regional (between- and within-
county) differences in mineral deficiencies in cattle are known. For example,
before widespread routine adoption of mineral supplementation in dairy herds,
counties Clare and Carlow had the lowest bovine blood levels of I and Se in the
Republic. Also, Mo-induced Cu deficiency is especially common on shale soils
and in pastures reclaimed from Bord na Mona cut-over peat soils.
However, for many reasons, it is
impractical for the feed mills and mineral-mix trade to try to formulate
regional mineral mixtures because, for example, Kerry feeds are sold in
Monaghan and vice-versa. Therefore,
we must be content with NATIONAL feed- and mineral-mix- formulations that
supply generous but safe levels of the essential major and trace minerals in
the daily allowance to cattle.
Suggested national targets for
supplementary major and trace elements for cattle and sheep are in tables 3 and
4 of “Control of Mineral Imbalances in Cattle and Sheep: A Reference Manual
for Advisers and Vets” at http://homepage.eircom.net/~progers/tahip/3control.htm
Targets extracted from those tables
for cows are:
Table 3. Suggested optimum supplementation
levels of Major Elements for stock. The supplementation level of Ca, P
and Mg for cows is usually in the range 0-50% of minimum daily requirement.
That of Mg rises to 100% in the tetany season. That of Na is usually 20-40% but
may be 140% or more if salt is supplied ad libitum.
Recommended supplement
of major elements (g/cow/d)
Animal |
Ca |
P |
Mg |
Na |
Dry cows |
0-5 (0*) |
0-30 |
5-15 (15*) |
6-23 |
Lactating & Suckler cows |
0-40 |
5-30 |
5-50** |
6-23 |
(*) The optimal Ca
and Mg supplements for Dry Cows on silage or grass are 0 and 15 g/cow/d,
respectively.
(**) The higher Mg
supplements (20-50 g/d for calved cows) are for use in the tetany seasons.
Otherwise a Mg supplement of 5-10 g/d for cows is enough in lactation.
Table 4. Suggested optimum supplementation
levels of Trace Elements for stock. Except for Cu in sheep and Fe in all stock,
the minimum supplementation level of trace elements is set at 100% of minimum
daily requirement, i.e. it ignores background levels in forage.
Recommended trace
element supplement (mg/cow/d)
Animal |
Cu* |
Se** |
I |
Co |
Mn^ |
Zn*** |
Fe |
All cows |
150-450 |
3.0-5.0 |
12-60 |
5-10 |
335-415 |
335-750 |
0-300 |
The lower
levels are for routine continuous use. With the following exceptions, the higher
levels are advised for national use in the Teagasc 5-month mineral
programme for cows (1 month prepartum to 5 months postpartum; see Addendum: “Comparative
costs of mineral supplements for cows from 1 month pre- to 4 months post-
calving” [ http://homepage.eircom.net/~progers/tahip/3control.htm#costs
], or as needed in groups of cattle
at risk of severe deficiency:
^ Some authorities
advise much higher Mn supplements (up to 980 mg/cow/d) in herds with
severe infertility due to suspected Mn deficiency. A pro-rata dose for ewes
would be up to 98 mg Mn/d.
* Give Cu to sheep
only on veterinary confirmation of Cu deficiency.
** Within 5 miles
of known Se-toxic farms, reduce the Se supplement to about 50% of the
lower level, unless blood test confirms Se deficiency in the group.
*/** Ionophores (monensin etc)
increase the retention rate of Cu and Se by ruminants. If ionophores
are fed, avoid the higher levels of Cu and Se supplements, unless blood test
suggests that higher levels are needed.
*** Zn supplement of
up to maximum is advised if high-Ca diets are fed.
4. MINERAL SUPPLEMENTATION METHODS (see references 2
and 3 for
details)
These will be discussed in relation
to:
(a) Fixed rate supplementation (best method) and
(b) Ad libitum supplementation (second class;
hit-and-miss; many cows unprotected and some take far too much).
(a) Fixed rate supplementation (best method)
(b) Ad libitum supplementation: This uses commercial mineral blocks or licks, or
DIY mixtures, such as 50:50 calcined magnesite:molasses, or high-magnesium
pasture mineral + molasses. Though better than no supplementation, ad libitum supplementation is second rate. It should be considered only in
marginal areas for herds whose managers cannot use a better fixed-rate
supplementation method. The main problem with ad libitum methods huge
variation in intake between cows. Intake can vary from 0-400g/cow/d.
Even at a narrower range (10-300g/d), the variation between cows can be
30-fold. Also, intake is not random; some cows consistently take too much and
some take little or none.
5. ADVANTAGES AND DISADVANTAGES OF THE DIFFERENT METHODS OF
SUPPLEMENTATION
These will be discussed in relation
to:
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
Excellent veterinary products that supply a single trace element include:
o
CuO capsules (24 g CuO orally gives 2-4 months
protection in cattle);
o
Cu-EDTA injection (100 mg Cu (subcutaneous) gives 6-12 weeks protection in cattle, but is
a less preferred way to supplement with Cu).
o
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.
o
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].
o
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.
o
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.
o
Multiple trace element deficiency often occurs in Irish herds. Therefore, at least Cu, Co, Se and I supplements are
advisable during a 5-month period, from 1 month before calving to 4 months
after calving. Also, a high Mg supplement (30g Mg/cow/d) is needed during the
tetany season and a moderate Mg supplement (15g Mg/cow/d) is needed for 1 month
pre-calving. In that case, routine use of multiple veterinary products can be
very expensive. Even if "Cosecure", "Alltrace" or "Ionox"
bullets can be used, oral mineral supplements may be considered as a good
alternative on economic grounds because at least many bullets/cow/year are
needed under Irish conditions. For example:
o
Alltrace boluses (
|
Medium Teagasc Target (mg/cow/d) |
Quantity (mg) in each Alltrace bolus |
Daily supply per bolus
over 240 days |
Boluses needed every
240 days to supply medium Teagasc Target |
Se |
4 |
251 |
1.045 |
3.8 |
Cu |
300 |
16379 |
68.2 |
4.4 |
Co |
7.5 |
236 |
0.98 |
7.6 |
Zn |
543 |
13382 |
55.8 |
9.7 |
Mn |
375 |
8326 |
34.7 |
10.8 |
I |
30 |
497 |
2.07 |
14.5 |
o
Cosecure boluses (
|
Medium Teagasc Target (mg/cow/d) |
Quantity (mg) in each Cosecure
bolus |
Daily supply per bolus over 180 days |
Boluses needed every 180 days to supply medium Teagasc Target |
Cu |
300 |
13400 |
74.4 |
4.0 |
Co |
7.5 |
500 |
2.78 |
2.7 |
Se |
4 |
300 |
1.67 |
2.4 |
o
Ionox
boluses (Bayer,
|
Medium Teagasc Target (mg/cow/d) |
Quantity (mg) in each Ionox bolus |
Daily supply per bolus
over 196 days |
Boluses needed every
196 days to supply medium Teagasc Target |
I |
30 |
3500 |
17.9 |
1.68 |
Se |
4 |
500 |
2.55 |
1.57 |
Co |
7.5 |
350 |
1.79 |
4.20 |
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 boluses: These Agrimin boluses do not
release enough Zn, Mn or I (see the Alltrace table,
above) to make them effective supplements if those elements are seriously
deficient in a herd.
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.
In
conclusion, Irish forages (pasture and grass silage) have
multi-imbalances of major and trace minerals. These imbalances sometimes (but
not always) cause clinical or subclinical problems.
Optimal mineral nutrition of Irish cows on forage-based diets involves
routine supplementation to ensure balanced inputs of the essential major- and
trace- elements to ensure that neither deficiencies (primary or secondary) nor
toxicities occur. Most cow farmers should supplement for 5 months (1 month before calving to 4 months
after calving).
Supplementation outside of that 5-month window may
be needed in special cases, for example in abortion due to I deficiency, or in
tetany outside of the normal risk period.
Serious dairy farmers should use fixed-rate
methods of mineral supplementation, IN FEED, ON FEED, or IN WATER.
Farmers using mineral mixes need at least THREE different mineral formulations:
1. Dry Cow Formula usually sprinkled on silage at 100g/cow/d for circa
1 month prepartum;
2. Lactation Formula, usually included at 125-150g/cow/d in dairy
concentrate, fed at 6-7 kg/cow/d indoors;
3. High-Mg (tetany control) formula, with high trace-elements, usually included at 140-170g/cow/d in a pasture nut, fed at 1, or 2, or 3 kg/cow/d.
Farmers feeding a lot of
maize-silage, or fodder-beet need special mineral balancers for those feeds.
For details on methods of control of bovine mineral imbalances, see the REFERENCES, especially references (2 and 3).
REFERENCES [further
reading]
1.
2. Rogers PAM & Gately T
(1993) Control of Mineral Imbalances in
Cattle and Sheep: A Reference Manual for Advisers and Vets. http://homepage.eircom.net/~progers/tahip/3control.htm
3.
4.
White ME (2005)
Cornell Consultant: Online Veterinary Diagnostic Software. http://www.vet.cornell.edu/consultant/Consult.asp?
5. Rogers PAM (2001)
Hypocalcaemia & Milk Fever in Cows. http://homepage.eircom.net/~progers/tahip/milkfeve.htm
6.
7.
8.
9. Rogers
PAM, Arora SP, Fleming GA, Crinion RAP & McLaughlin JG (1990) Selenium toxicity in farm
animals: treatment and prevention. http://homepage.eircom.net/~progers/tahip/setoxicity.htm
10.
11.
12.
13.
14.
15. Rogers PAM, Gately TF & Keating T
(2000) Teagasc Farm
Nutrient Profile: Reference Information for Professionals. http://homepage.eircom.net/~progers/tahip/2manual.htm