Notes on Minerals, Vitamins, Supplements, and Additives in Animal Nutrition

Mineral Supplements

  • Essential Role: Supplemental minerals are critical to meet the mineral needs of livestock.
  • Lab Analysis: Accurate assessment of mineral content in feedstuffs requires laboratory analysis.
  • Bioavailability: This refers to the proportion of minerals in feed that is actually absorbed.
    • Factors Affecting Bioavailability:
    • Mineral Source: Organic complexed minerals are often more bioavailable than inorganic ones.
      • More Bioavailable Forms: Sulfate, carbonate, and chloride forms vs. oxide forms.
    • Processing Method: Ground minerals are more bioavailable than granular forms.
    • Livestock Species: Different species (ruminants vs. non-ruminants) absorb minerals differently.
  • Safety Factors: Adjustments to mineral concentrations may be needed when bioavailability is unknown.
  • Palatability Issues: Many mineral sources are unpalatable; salt can be used to enhance taste.
  • Forms of Minerals Available:
    • Loose form
    • Block form

Vitamin Supplements

  • Vitamin Content Variability: The vitamin content in feedstuffs varies based on:
    • Type of feedstuff
    • Management during harvesting (e.g., bleaching)
    • Processing methods (e.g., extrusion)
    • Conditions and duration of storage.
  • Analysis Requirement: Regular analysis of vitamins in feed ingredients is essential, often involving expensive chromatographic methods.

Liquid Feeds

  • Types of Liquid Feeds: Includes distillers’ solubles, fish solubles, corn fermentation solubles, molasses, oil, etc.
  • Most Common: Molasses and vegetable oils are widely used.
  • Uses of Molasses:
    • Acts as a carrier for nutrients like urea, fat, vitamins, trace minerals, yeast cultures, and ionophores.
  • Benefits of Liquid Supplementation:
    • Increases ration density and palatability.
    • Promotes uniform nutrient distribution, reducing animal sorting and feed wastage.

Feed Additives

  • Definition: Products that enhance the quality of feed and improve animal health/performance.
    • Common Types:
    • Buffers (e.g., sodium bicarbonate for ruminants)
    • Antioxidants (e.g., BHT, BHA)
    • Hormones (e.g., steroids, BST)
    • Antibiotics and chemotherapeutic agents to control infections.
  • Additional Additives:
    • Flavors for palatability, probiotics for microbial growth enhancement, enzymes (e.g., phytase), pigments, mold inhibitors, and mycotoxin binders.
  • Purpose of Additives:
    • Stimulate growth, enhance feed efficiency, promote general health, extend feed shelf life.

Antibiotics

  • Feed Use: Administered at sub-therapeutic levels in livestock diets (2-10 mg/kg).
  • Therapeutic Use: Higher doses are required to treat established infections.
  • Benefits:
    • Reduces subclinical bacterial infections.
    • Improves growth rate and feed efficiency.
    • Controls respiratory infections, liver abscesses, foot rot in livestock, and diarrhea.

Ionophores

  • Definition: Antibiotic-like compounds that transport ions across cell membranes.
  • Uses:
    • Prevent coccidiosis, improve feed efficiency in ruminants.
    • Potentially toxic to horses (monensin levels above 1.4 mg/kg).
  • Mechanism of Action:
    • Disrupts potassium balance in sensitive Gram-positive bacteria, leading to acidic cell conditions and energy depletion.
  • Clinical Signs of Poisoning in Horses:
    • Poor appetite, diarrhea, weakness, rapid heart rate, depression, wobbly gait, colic, and potential fatality.

Effects of Feeding Ionophores on Rumen Metabolism

  • Production Changes:
    • Increases propionate production and decreases methane production.
    • Reduces deamination of amino acids, enhancing energy efficiency.

Phytase and Phytic Acid

  • Roles of Phytase:
    • Breaks down phytic acid in feedstuffs (e.g., oilseed meals), releasing phosphorus for absorption.

Summary and Key Points

  • Minerals exhibit varying bioavailability and often require force-feeding due to palatability issues.
  • Molasses and oils are primary liquid feeds.
  • Feed additives serve to improve feed efficiency and animal growth health without fulfilling any specific nutrient requirements.