L14. Nutrition, Production and Health Aspects of Mineral and Vitamin Nutrition - Calcium

Minerals are essential for muscle development, bone development, fertility, appetite, foetal development, nervous system, disease resistance etc.

Function of Minerals

  • structural function
  • physiological function
    • acid-base balance, osmotic pressure, membrane permeability, the transmission of nerve impulses
  • catalytic function
    • part of metal enzymes, hormones and coenzymes
  • regulatory function

The concentration of minerals in feed is affected by:

  • type of plant
  • soil conditions
  • climatic conditions
  • maturity

The requirements for minerals are determined by:

  • absorption
  • metabolism
  • production

The requirements for minerals are affected by:

  • physiological factors
  • nutritional factors
  • level of production

Absorption and Metabolism of minerals are by:

  • active transport
  • passive transport
  • mutual interaction of minerals

Trace Mineral Deficiency

  • Primary
    • caused by inadequate dietary mineral intake
  • Secondary
    • caused by a factor interfering with mineral absorption and/or metabolism

Nutritional Requirements for Minerals

  • Requirements are affected by:
    • absorption by active transport or passive transport
    • genetic potential and type of production
    • maintenance
    • growth
    • reproduction
    • production
    • ages of animals
    • sex
  • Evaluation of mineral nutrition:
    • analysis in feeds and calculation in daily feed ration
    • analysis in total mix ration (TMR)
    • analysis in blood, resp. specific tissue
  • Management of mineral nutrition
    • addition to grain mixtures, resp. TMR
    • supplementation in the form of mineral-vitamin supplements
    • specific in the grazing system

Milk Fever - Postpartum Hypocalcaemia

Function of Calcium

  • calcium - important physiological cation
  • ions - intracellular and extracellular fluids
  • ions - control a large number of biochemical processes
    • muscle contraction
    • blood coagulation
    • hormone release
    • skeleton integrity
    • activity of a large number of enzymes
    • conveying information from the surface to the interior of the cell

Homeostasis of Calcium Concentration

  • Decreased intake Ca
  • Decreased absorption of Ca from GIT
  • Decreased Ca in blood
  • Increased secretion of PTH
  • Increased absorption of Ca from GIT and increased resorption from bones
  • Increased Ca in the blood
  • Decreased secretion PTH
  • Decreased α-hydroxylase in kidney
  • Decreased activated vitamin D
  • Decreased absorption of Ca from GIT

Nutritional Factors Determining the Manifestation of Postpartum Hypocalcaemia

Hypocalcaemia: decrease in serum concentration of Ca below 2.0 mmol/l

Causes:

  • high need for Ca for the synthesis of colostrum (2.3 g/l) or milk (1.3 g/l)
  • Disorder of homeostatic regulation of Ca

  1. Insufficient nutritional adaptation of Ca metabolism - before parturition

    1. high Ca intake above 80 g/day does not activate regulatory mechanisms

    2. regulatory mechanisms

      1. parathyroid hormone (PTH)
      2. bones
      3. α-hydroxylase & 1.25-dihydroxy-vitamin D

  2. Metabolic alkalosis - pH of blood over 7.45

    1. at higher proportions of cations (K, Na) in the TMR alkalise the internal environment

    2. regulates the effect of

      1. PTH on bone

        1. reduced Ca release

      2. PTH on kidney

        1. reduced α-hydroxylase synthesis and calcium resorption

  3. Hypomagnesemia - Mg < 0.65 mmol/l can also affect Ca metabolism

    1. reduces PTH secretion
    2. reduces the sensitivity of tissues to PTH

  4. Phosphorus concentration in blood - P > 2.2 mmol/l inhibits secretion of α-hydroxylase