Mineral Nutrition for Ruminants

Major Minerals

Major (macro) mineralsCa, P, K, Mg, Na, Cl, S Included as % in diet

FunctionsStructuralNerveElectrolytesOsmotic balanceBuffer in the rumen

Trace Minerals

Trace (micro) mineralsCobalt, copper, iodine, iron, manganese,

molybdenum, selenium and zinc all requiredChromium-no established requirement Included as ppm or ppb in diet

FunctionEnzyme co-factor or component

Mineral Deficiencies

Milk Fever

Metabolic disease at/after parturition in dairy cows

Rapid decrease in serum Ca because Ca is lost to colostrum secretion

Symptoms included lack of appetite and paralysis

Treatment is intravenous Ca borogluconate

Milk Fever Prevention Include anionic salts in diet for 3-5 wks prior to

parturitionmEq(Na+ + K+) – mEq(Cl- + SO4

-)

Normal diet: +20 to +30 mEq/100g diet (electrolyte balance)

Anionic diet: -7 to -25 mEq/100g diet Induces mild acidosis, which increases tissue

responsiveness to PTHCa release from bone to serum

Grass Tetany

Hypomagnesemia in ruminants Usually following lush spring growth Fertilizing with K or N make it worse Symptoms include muscular twitching,

collapse, convulsionTreatment is Intravenous injection (IV) Mg

gluconatePrevent with high Mag mineral (MagOx)

Copper, sulfur and molybdenum

High sulfur & molybdenum thiomolybdates Cu + thiomolybdates insoluble complexes Thiomolybdates can result in reduced Cu absorption and

systemic metabolism

NRC, 1996

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 114 183 241 297 422 459 490

Pla

sma

Cu

, mg

/L

Calf day of age

Cu Adequate Cu Def icient Cu Def icient + Mn

Mineral Toxicosis

Maximum Tolerable Levels for Ruminants

Copper Toxicosis

Sheep particularly sensitive to copper5 ppm CuExcessive Cu builds up in Red Blood Cells,

causing Heinz-body formation and methemoglobin production

Can’t bind oxygen-chocolate bloodRelease of hemoglobin damages kidneys

Avoid feeding cattle mineral

Copper Toxicosis Treatment

IV methylene blue to control metHb Copper chelators

D-penicillamine Ammonium tetrathiomolybdate

Cu:Mo ratio of 10:1 or less

Sulfur Toxicity in Ruminants

Dietary sulfate reduced to H2S (gas) Eructate-reinhale Toxic in high amounts

Polioencephalomalacia (PEM, brainers)

Brain lesions due to S toxicity

Polioencephalomalacia (PEM) Terminology

Polio = gray matter Encephalo = brain Malacia = tissue death

Clinical signs Subacute – head pressing, circling, ataxia, staggering,

blindness, depression, stupor Acute – blindness, seizures, comatose

Can be caused by thiamine deficiency, lead or salt poisoning and high sulfur diets

S induced PEM

Does not appear to be caused by thiamine or copper deficiency No alterations of thiamine or its mono- and diphosphate esters in

whole blood, brain, cerebrospinal fluid, or liver (Sager et al., 1990; Gould et al.,1991)

Thiamine treatment can help reduce symptoms Increase energy availability to the brain

plays a key role in the tri-carboxcylic acid cycle and pentose shunt Thiamine-supplemented groups also manifested PEM, even

though clinical signs were not observed (Olkowski et al., 1992).

Pka of HS- = 7.04

60% of ruminal gas that is eructated is inhaled

S Induced PEM

Oxidative Stress

Reactive oxygen compoundByproduct of cellular respirationRoles in cell signallingDangerous in excess

Oxygen CompoundHydroxylSuperoxideHydrogen peroxide

Oxidative Stress

EffectsDNA damageLipid peroxidation (oxidation of

polyunsaturated fatty acids) Inactivation of some enzymes (oxidation of

metal cofactors)

Antioxidant Capacity

Superoxide dismutaseSuperoxide anion to hydrogen peroxideCopper-Zinc SOD-cytosolManganese SOD-mitochondria

http://en.wikipedia.org/wiki/Superoxide_dismutase

Antioxidant Capacity

CatalaseHydrogen peroxide to water and oxygenConsists of 4 parts, each containing a heme

(iron) group

Antioxidant Capacity

Glutathione peroxidaseHydrogen peroxide to waterSelenium dependent enzyme-4 selenium

atoms per molecule

Iodine

Function- part of thyroid hormone (metabolism rate)70-80% of body I- is in thyroidT4 (thyroxine)T3 (triiodothyronine)-3 times more active than

T4Controls rate of energy metabolism in cells

Iodine

Deficiency “goiter” enlarged thyroid gland

Plants have “goitrogens” (goiter creating), block use of iodine

Reduced growth Impaired reproduction-dead, weak or

hairless young

Goiter in lamb

Selenium

Regulated by the FDA, because relatively low levels toxic (i.e. 10x requirement)

Function Glutathione peroxidase (antioxidant) Iodothyronine 5’-deiodinase-1 (T4 conversion to T3)

Selenium

Deficiency Deficient in many areas of U.S. Muscular dystrophy

Sheep-white muscle disease Reproductive problems such as retained placenta and

low fertility, weak newborns

Cobalt

Essential component of B12 Required by ruminants Rumen microorganisms synthesize B12

from cobalt B12 dependent enzymes

Methylmalonyl-CoA mutaseMethionine synthetase