Mineral Nutrition in Animals

Mineral Nutrition

Dr. Paula Gonzalez-Rivas/ Technical Services Manager - Livestock Nutrition / Virbac Australia

Outline for the Next 2 Lectures

• Basics information about mineral nutrition, deficiencies, and toxicities.

• Macro minerals.

• Trace minerals.

• Supplementation strategies.

Learning Outcomes

• To describe the function of macro and trace minerals in animal metabolism.

• To identify the symptoms associated with mineral deficiencies and toxicities.

• To identify sources of minerals.

• To identify interactions between minerals and their importance for animal nutrition.

• To identify the types of mineral supplements.

References

• Minerals in Animal and Human Nutrition, Seventh Edition, Lee Russell McDowell.

• Mineral Nutrition of Livestock, 5th Edition, Neville F. Suttle.

• Animal Nutrition, P. McDonald, R. A. Edwards, J. F. D. Greenhalgh, C. A. Morgan, L. A. Sinclair, R. G. Wilkinson, Elsevier.

Further Reading

• CABI (Centre for Agriculture and Bioscience International).

Further Listening

• The Beef Podcast (Episodes #37 and #49: "Modernizing Vitamin and Vitamin Mineral Inclusion for Beef Cattle" by Dr. Stephanie Hansen, Iowa State University).

• The Dairy Podcast: "Mineral Matters: Enhancing Livestock Health in Dairy Farming" by Dr. Robert VanSaun, Penn State University.

Nutrient Classification

• Food/Feed Components:

  • Dry matter

  • Organic:

  • Carbohydrates (CHO)

  • Lipids

  • Proteins

  • Vitamins

  • Inorganic:

  • Minerals:

    • Macro Minerals

    • Micro (Trace) Minerals

    • Water

Functions of Minerals in Metabolism

• Catalytic: Enzyme cofactors in metabolic processes.

• Structural: Calcium (Ca) and Phosphorus (P) in bone.

• Regulatory: Acid-base and water balance (Sodium (Na), Potassium (K), Chloride (Cl)).

• Physiological: Cobalt (Co) in vitamin B12, Iodine (I) in thyroid hormones, muscle contraction, nerve function.

Mineral Absorption

• Passive Absorption: Diffusion along a concentration gradient.

• Active Absorption: Carrier-mediated transport system.

• Absorption sites vary depending on digestive anatomy and conditions within the digestive tract (pH).

• Rumen pH (a reductive environment) affects solubility and produces mineral complex formation.

Mineral Storage

• Some minerals have large storage depots, primarily in the liver, kidney, and bone.

• Blood plasma is usually the central or interchange pool.

• Organs like the liver, kidney, and gut are of high metabolic activity and require minerals for enzyme activity.

Basic Concepts

• Bioavailability: The proportion of a nutrient that can be:

  1. Digested.

  2. Absorbed.

  3. Utilized for storage and metabolism.

• Solubility ≠ Absorbability: Solubility does not guarantee absorption.

• Absorption Coefficient: Not always indicative of potential absorbability.

• Absorbability ≠ Availability: Absorbability does not guarantee that the nutrient is available for use by the body.

Classification of Minerals

• Macro Minerals:

  • Sodium (Na), Potassium (K), Magnesium (Mg), Calcium (Ca), Phosphorus (P), Chloride (Cl), Sulfur (S).

  • Present in body tissues at concentrations > 100 mg/kg (g/kg DM).

  • Have large daily requirements.

• Trace Minerals:

  • Chromium (Cr), Manganese (Mn), Iodine (I), Iron (Fe), Cobalt (Co), Molybdenum (Mo), Zinc (Zn), Selenium (Se).

  • Present in body tissues at concentrations < 100 mg/kg (100 ppm).

  • Have small daily requirements (mg/kg DM (ppm)).

Factors Affecting Mineral Requirements

• Physiological state/level of production.

• Interactions with other minerals.

• Tissue storage.

• Form (Inorganic vs Organic, Oral vs Injectable).

• Distinction between tissue and rumen microbe requirements for ruminants.

Mineral Interactions

• Mineral Interference and Synergy:

  • P (Phosphorus)

  • Cr (Chromium)

  • Co (Cobalt)

  • Pb (Lead)

  • Fe (Iron)

  • Se (Selenium)

  • Na (Sodium)

  • Ca (Calcium)

  • High concentrations can lead to mutual interference and potential toxicity.

• The direction of arrows in the diagram denotes interference.

  • Arrows aimed at each other denote mineral synergy.

  • Arrows aimed away from each other denote mutual mineral interference or antagonism.

Deficiency and Toxicity

• Most minerals have a reference range to avoid deficiency and toxicity symptoms.

• Symptoms appear when mineral levels fall below or exceed this range.

• Mineral content of soils dictates mineral status of plants (and subsequently animals).

• Deficiency symptoms may take months to develop and are often subclinical, making them difficult to determine, yet result in significant economic losses.

Subclinical Deficiencies

• Represent high economic losses, with clinical conditions including:

  • White Muscle Disease

  • Swayback

  • Discolored coat

  • Broken bones

• Clinical symptoms include:

  • Mastitis

  • Scours (diarrhea)

  • Bovine Respiratory Disease (BRD)

  • Reduced fertility

  • Poor immunity

  • High culling rates

  • High worm egg counts

  • Reduced weight gain

  • Mortality in lambs/calves

  • Poor wool quality

  • Hoof issues

  • Extended calving patterns.

Importance of Soil and Plant Science

• Most Australian livestock are pasture-fed, making mineral intake dependent on plant tissue mineral content.

• Plant mineral content is influenced by soil mineral levels, which are determined by geography, rainfall patterns, and management practices.

Macro Minerals

Calcium (Ca)

Function

• Most abundant mineral in animal tissues, constituting 99% of the skeleton and teeth.

• Acts as a reservoir in bone.

• Functions include:

  • Bone structure

  • Nerve impulse transmission

  • Blood clotting

  • Muscle contraction

  • Cellular metabolism.

Food Sources

• High bioavailability sources include:

  • Milk and dairy products (fortified with vitamin D).

  • Green leafy vegetables (though absorption can be poor).

  • Fish with bones.

  • Fortified juice/cereal.

Feed Sources

• Colostrum and milk.

• Green leafy crops (legumes, sugar beet pulp).

• Cereal and root crops (generally poor sources unless supplemented) - limestone or calcium sources are suggested.

• Cereal by-products such as bran can be high in phosphorus (P), which leads to calcium deficiency when the Ca:P ratio is < 1:1.

• High fat in monogastric diets can form calcium soaps, hindering calcium absorption.

Calcium Requirements

• Laying hens have significantly higher calcium requirements for egg formation (Ca:P ratio 3.5:1).

• Monogastrics need a Ca:P ratio of 1-2:1; ruminants may require up to 8:1 (not less than 1:1).

• Due to saliva secretion, large amounts of phosphorus are present during rumination; thus, caution should be taken when feeding human food low in calcium to pets.

• Calcium absorption is heightened during critical life stages such as egg-laying, growth, pregnancy, and lactation.

Calcium Metabolism

• Certain tropical grasses (e.g., Setaria) are high in oxalates, inducing calcium deficiencies (e.g., big head in horses).

• Bioavailability may be decreased by phytates, especially in low estrogen environments (e.g., postmenopausal women).

Calcium Regulation Hormones

• Vitamin D3 (1,25-dihydroxycholecalciferol) from the kidney and Parathyroid Hormone (PTH) regulate calcium levels, promoting calcium uptake, while Calcitonin from the thyroid gland decreases plasma calcium levels.

Calcium Deficiencies

• Rickets in young animals, osteomalacia in mature animals.

• Symptoms include misshapen bones, enlarged joints, lameness, and stiffness.

• Associated with deficiencies in vitamin D and phosphorus.

• Milk fever in lactating animals and eclampsia in canines.

• High milk production increases calcium loss through milk, hence the need for appropriate dietary management to avoid calcium depletion post-calving.

Milk Fever

• Common in high-producing dairy cows post-calving and twin-bearing ewes pre-lambing.

• Increases with age in cows (>4 years).

• Affects about 10% of cows if >3% require treatment after calving.

• Conditions arise due to sudden calcium demand exceeding dietary intake or absorption capabilities.

• Associated risks include dystocia, retained membranes, ketosis, mastitis, and displacement of the abomasum.

Hypocalcemia Clinical Signs

• Stage 1: Off-feed, aggressive behavior, staggering, falls, muscle tremors, cessation of rumen movement.

• Stage 2: Recumbent position on chest with S-shaped neck, dry muzzle, cold ears, lethargic.

• Stage 3: Coma or death with low blood calcium levels (3-7 mg/100 ml; normal ~10 mg/100 ml).

Treatment and Prevention of Milk Fever

• Administer slow IV calcium using calcium borogluconate (25-40%).

• Prevent by managing dietary calcium well in advance of calving and ensuring adequate dietary vitamin D.

• Supplementation strategies involve low dietary calcium in late gestation, providing calcium drenching right before calving, and maintaining high calcium diets post-calving.

Negative Dietary Cation-Anion Difference (DCAD)

• DCAD measures the levels of macro minerals in the diet: high potassium (K) and sodium (Na) as cations, chloride (Cl) and sulfur (S) as anions.

• A negative DCAD favors calcium transfer from bones to bloodstream, reducing milk fever chances. Targeting a DCAD between -50 mEq/kg and -200 mEq/kg DM is optimal for managing calcium levels. Urine pH monitoring should maintain around 6.0 to 6.5.

Eclampsia in Bitches

• A serious condition stemming from hypocalcemia, commonly occurs 1-3 weeks post-whelping or during gestation.

• Small breeds may be predisposed, with contributing factors being poor nutrition and high milk production.

• Treatment involves administering calcium gluconate (5-10 ml of 10% solution based on dog weight), while dietary calcium and vitamin D can provide preventive benefits.

Nutritional Secondary Hyper-parathyroidism (Big Head)

• Primarily a severe calcium deficiency condition observed in horses.

• Results in the mobilization of calcium from facial and pelvic bones, making them fragile, causing significant skeletal issues.

Osteoporosis

• Significant decline in the calcium mass of bones as one ages, with recommendations to maintain adequate calcium and vitamin D intake and engage in weight-bearing exercises.

Calcium Excesses

• High calcium intake from supplements can lead to adverse effects like kidney stones and impairment in the absorption of other minerals (Zn, Mg, P, S, Mn).

Phosphorus (P)

Function

• The second-largest component of bones and teeth (80-85%).

• Vital structural component of nucleic acids (RNA and DNA).

• Critical in energy production via high-energy compounds like ATP.

• Part of cell membranes as phospholipids.

Food Sources

• Good sources include milk and cereal grains (phytate form). Poor sources are hays and straws, with bioavailability improved by destroying phytate phosphorus (not an issue in ruminants due to bacterial phytase production).

Phosphorus Metabolism

• Easily absorbed via passive and active mechanisms in the small intestine.

• Excreted in urine (monogastrics) and feces (ruminants) with a large recycling in ruminant saliva.

Phosphorus Deficiency

• Rickets or osteomalacia often related to calcium and vitamin D deficiencies.

• Can cause 'Pica', where cows in phosphorus-deficient regions chew on bones at risk of botulism.

• Young animals in phosphorus-deficient areas can develop stiff joints, muscular weakness, reduced growth rates, and fertility issues.

Phosphorus Excess

• High phosphorus intake leads to mineral salt deposits, causing urinary blockages (urolithiasis), potentially resulting in death, especially in feedlot sheep.

Potassium (K)

Function

• The third most abundant mineral in the body.

• Essential for osmotic regulation of body fluids, acid-base balance, nerve and muscle excitability, and activation of enzymes involved in carbohydrate metabolism.

Sources of Potassium

• Most feeds are generally adequate in potassium, requiring daily supplies due to poor storage capability.

Potassium Deficiency

• Rare but can occur due to grazing on mineral-leached pastures, heat stress, dehydration, or excessive sweating, leading to severe muscle issues, weakness, and potential cardiac arrest.

Potassium Excess

• High potassium can reduce magnesium absorption and potentially lead to renal failure. Genetic mutations related to potassium excess can trigger serious muscle twitching or paralysis in horses (Hyperkalemic Periodic Paralysis).

Sodium (Na)

Function

• Present in soft tissues and fluids as the major cation of extracellular fluid. It plays a crucial role in acid-base balance, osmotic regulation, and nerve impulse transmission.

Sources of Sodium

• Salt is commonly added to supplements to encourage feed and water intake. Some forages are naturally low in sodium, necessitating supplement use.

Sodium Deficiency

• Leads to decreased osmotic pressure and severe dehydration, resulting in poor growth, anorexia, and reproductive disturbances.

• Ruminants often display high appetite for salt due to physiological needs for sodium regulation.

Sodium Excess

• Excessive sodium intake can lead to high blood pressure, muscle weakness, and salt poisoning, particularly common Among pigs and poultry.

Magnesium (Mg)

Function

• About 70% of magnesium is found in the skeleton. It is crucial for activating enzymes in energy metabolism, moderating neuromuscular activity, and maintaining cellular integrity.

Magnesium Sources

• Found in cereals, soy, and magnesium-containing fertilizers.

Grass Tetany

• Characterized by hypomagnesemic tetany, grass staggers, or lactation tetany affecting grazing livestock primarily during specific seasons (autumn and winter).

• Symptoms include restlessness, muscle twitching, and lack of coordination. Treatment involves magnesium supplements, while prevention requires proper dietary management.

Chlorine (Cl)

Function

• Regulates acid-base balance and osmotic pressure. Component of gastric secretions (HCl).

Sulfur (S)

Function

• Key component of body proteins (cysteine, methionine), vitamins, bone/cartilage structure, and essential for rumen microbial function.

• Its levels must be balanced with molybdenum to avoid deficiencies in copper absorption in ruminants.

Sulfur Toxicity

• Excess sulfur (above 0.4% DM) can lead to severe toxic effects, including neurological damage.