Macrominerals in Animal Nutrition

Macrominerals

Introduction to Macrominerals

• Macrominerals are essential minerals required by the body in larger quantities.

Periodic Table of the Elements

• Displays a variety of elements including macrominerals:

  • Hydrogen (H), Lithium (Li), Sodium (Na), Magnesium (Mg), Calcium (Ca), Potassium (K), Phosphorus (P), Sulfur (S), Sodium (Na), Chlorine (Cl), and Magnesium (Mg).

Learning Objectives

1. Understand and describe the main functions of macrominerals in the body.

2. List the major sources of macrominerals in the diet.

3. Understand how macromineral deficiencies impact animal health.

4. Understand the major biological mechanisms involving macromineral deficiencies.

Criteria for an Essential Mineral

• Removal: Analyze the effect of removing the mineral from the diet.

• Physiological Abnormality: If withdrawal leads to physiological abnormalities or biochemical reactions.

• Re-addition: If re-adding the mineral alleviates deficiency signs, it is considered essential.

Nutrient Requirements Series

• Updated expert reports periodically from 1945, reflecting research findings on different species.

Recommended Dietary Allowances (RDA)

• The first edition of RDAs published in 1943 during World War II, aiming to provide guidelines for nutrient intake.

General Functions of Minerals

1. Skeletal Structure Components: Primarily Calcium (Ca), Phosphorus (P), and Magnesium (Mg).

2. Osmotic Pressure Maintenance: Sodium (Na), Potassium (K), Magnesium (Mg), and Chlorine (Cl) help maintain osmotic balance.

3. Acid-Base Regulation: Minerals are involved in the regulation of acid-base balance.

4. Biochemical Reaction Catalysts: Minerals serve as components or activators of various enzymes and biochemical reactions:

   • Selenium: In glutathione peroxidase.

   • Iron: Essential for hemoglobin.

   • Calcium, Manganese, Magnesium: Serve as cofactors in various enzymatic reactions.

   • Iodine: Essential for thyroid hormones.

   • Cobalt: Forms cyanocobalamin (vitamin B12).

   • Copper: Involvement in cytochrome C oxidase.

Routes for Mineral Excretion

1. Urine: Major route for absorbed minerals.

2. Feces: Minerals excreted, whether absorbed or unabsorbed.

3. Sweat: Mainly Na and Cl, with also Mg and Ca.

4. Other routes: Such as bile, pancreatic juice, and direct secretion into the large intestine.

Factors Affecting Mineral Requirements

• Species or Breed Sensitivity: Different requirements for Copper (Cu) based on species (e.g., sheep vs. pigs).

• Rate of Growth: Higher growth rates correlate with higher mineral requirements.

• Physiological State: Lactation or egg-laying increases requirements.

• Chemical Form of Mineral: Chelated vs. inorganic forms affect absorption.

• Level of Other Minerals: Interactions can influence bioavailability (e.g., Cu and Zn).

Mineral Composition of the Body

Importance of Ash Analysis

• Definition: The mineral content of a sample representing the inorganic residues after burning.

• Significance: Minerals remain despite heat while organic components are lost, aiding in nutritional labeling and assessment of ingredient quality.

• Nutritional Classes Involved: Organic elements in nutrients like lipids, carbohydrates, and proteins (C, H, O, N, S).

Calcium (Ca)

• Atomic Weight: 40.08

Sources of Calcium

• Mineral sources:

  • Calcium Carbonate (limestone): Affordable source.

  • Dicalcium Phosphate (dical): Higher mineral availability.

• Animal Sources:

  • Fish meal, meat and bone meal, milk products.

• Plant Sources:

  • Rich in forages, poor in cereal grains.

Structural Role of Calcium

• Major component of bones and teeth (99% of body calcium).

• Stored majorly in bones as Hydroxyapatite crystals with composition:

  • $3Ca<em>3(PO</em>4)<em>2 \, Ca(OH)</em>2$ (Calcium Hydroxide).

• Bone Ash: 280 g calcium, 170 g phosphorus, 10 g magnesium.

Functions of Calcium

1. Structural support in bones and teeth.

2. Enzyme activation located in soft tissues including activation for:

   • Blood coagulation, impulse transmission at neuromuscular junctions, muscle contractions.

3. Maintains electrolyte balance influencing acid-base balance.

Calcium in Circulation

• Only 1% of total calcium circulates for:

  • Coagulation of blood, nerve stimulation, and maintenance of electrolytic balance.

• Regulated by:

  • Calcitonin: Reduces calcium.

  • Parathyroid Hormone (PTH): Increases calcium.

  • Vitamin D (1,25-(OH)2D): Increases calcium.

• Plasma calcium concentration is tightly regulated around 8.5-10 mg/dL in adult animals.

Calcium Deficiency Effects

• Can mimic P and Mg deficiencies.

• Symptoms include low growth rates and bone-related issues such as:

  • Rickets: Presents primarily in young animals with misshapen bones and stiffness.

  • Osteomalacia: “Adult rickets” with softening of bones due to inadequate calcification.

  • Osteoporosis: Characterized by reduced bone mass affecting 20 million Americans, particularly post-menopausal women.

• Peak Bone Mass illustrated:

  • Male: 1500g, Female: 1250g (underlines peak mass distribution across age).

Calcium Deficiency Causes

• Resulting from:

  • Absence of vitamin D, low Ca intake, low P and Mg intake, high-fat diets, and other nutritional imbalances causing Ca soap formation.

Calcium Deficiency in Dairy Cows

“Milk Fever”

• Results in an estimated $10 million loss annually, especially in high-yield dairy cows, within 0-12 hours post-calving.

• Normal blood Ca levels are between 8.5-10 mg/dL, which can drop to:

  • Subclinical: 6-8 mg/dL.

  • Hypocalcemic: < 5.5 mg/dL.

Preventive Measures in Dairy Cows

• Ensuring adequate dietary calcium:

  • Critical during final weeks of pregnancy, colostrum production, and lactation phases.

Phosphorus (P)

• Atomic Weight: 30.97

Sources of Phosphorus

• Animal Sources: Meat and bone meal, fish meal.

• Commercial Sources:

  • Dicalcium phosphate (~19% P, ~65% digestible),

  • Monocalcium phosphate (~23% P, ~80% digestible),

  • Defluorinated rock phosphate (fluoride removed).

• Importance of solubility, where monocal is notably more soluble than dical.

Phytate Sources and Considerations

• Phytate: Phytates are a form of phosphorus that most plant sources contain, presenting a challenge as it is largely unavailable (30 to 90% bioavailability issues).

• Phytase Enzyme: Required to liberate P from phytate, commercially sourced from bacteria and fungi.

• Ruminants can effectively use total phosphorus due to microbial activity in the rumen.

Functions of Phosphorus

• Similar roles to calcium in bone structure, maintaining acid-base balance, and in promoting carbohydrate metabolism.

• Important in enzyme regulation and synthesis of critical biological molecules such as DNA, RNA, ATP.

Phosphorus Deficiency

• Symptoms akin to deficiencies in calcium and vitamin D, leading to conditions like rickets and osteomalacia.

• Notably, the condition called ‘pica’ refers to depraved appetite indicating a severe deficiency can lead to unusual cravings, e.g., inedible items.

Potassium (K)

• Atomic Weight: 39.10

Sources of Potassium

• Found in:

  • Grains: 0.3-0.8%

  • Animal products: 0.3-2.0%

  • Vegetable proteins: 1.0-2.5% (notably high in forages like alfalfa).

Functions of Potassium

• Acts as an activator in multiple enzyme systems.

• Assists in osmotic balance and nerve impulse transmission.

• Responsible for maintaining acid-base balance, specifically noted by measuring the “Anion gap.”

Potassium Dietary Considerations

• Excess K can hinder Mg absorption, reducing overall growth and leading to weakness.

• Deficiency in K can cause serious health concerns and organ degeneration.

Sodium (Na)

• Atomic Weight: 22.99

Sources of Sodium

• Generally, plants contain low amounts (0.01-0.06%) while animal products (especially marine) can range higher (0.1-0.8%).

• Routine supplementation advised.

Functions of Sodium

1. Maintains osmotic balance and aids the absorption of carbohydrates and amino acids.

2. Essential for transmitting nerve impulses.

Sodium Deficiency Causes and Symptoms

• Deficiencies may arise due to lactation, rapid animal growth, or tropical conditions.

• Symptoms include salt cravings, poor growth, and reduced milk production.

Chlorine (Cl)

• Atomic Weight: 35.45

Functions of Chlorine

1. Helps in regulating osmotic pressure.

2. Vital for the formation of HCl in gastric juices for protein digestion and required for amylase activity.

Chlorine Deficiency Consequences

• Historically observed in infants on low chloride formulas leading to health recalls due to deficiency causing growth issues.

• Symptoms observed in affected population included depraved appetite and emaciation.

Sulfur (S)

• Atomic Weight: 32.06

Sources of Sulfur

• Primarily present in proteins (methionine and cysteine) and also in certain supplements.

Functions of Sulfur

• Present in glycosaminoglycans (e.g., chondroitin sulfate) which is of critical structural importance for connective tissue.

• Essential for optimal growth of rumen microbes, influencing overall nutrient digestibility.

Sulfur Deficiency and Toxicity Effects

• Deficiencies manifest as reduced appetite and growth, while excess can lead to severe neurological conditions and digestion issues.

Magnesium (Mg)

• Atomic Weight: 24.31

Sources of Magnesium

• Higher concentrations typically found in forages, lower in grains; absorption can be hindered by excessive levels of potassium and nitrogen.

Functions of Magnesium

• Integral for muscle and nerve function, regulating blood pressure, necessary for bone stability, and involves in metabolic reactions.

• A notable deficiency in grazing animals leads to ‘grass tetany’ or hypomagnesemia, resulting in severe health issues.

Treatment for Magnesium Deficiency

• Increasing circulation of Mg through IV solutions, dietary supplementation, or adjustment in grazing practices can mitigate risks associated with Mg deficiency.

Summary

• Macrominerals play crucial roles in various physiological and biological processes within animals, influencing everything from structural integrity of bones (Calcium, Phosphorus) to the regulation of metabolic processes (Sodium, Potassium, Magnesium). Their deficiencies can lead to serious health complications, and understanding their functions, sources, and regulatory mechanisms is essential for managing animal health and nutrition effectively.