Types of Milk Products Quiz

Milk Secretion and Let-Down

• Milk is released by alveoli into ducts, which carry milk to the gland cistern.
• 40% of milk is stored in the teat and gland cisterns, and the major ducts, while 60% is stored in the alveoli.
• Alveoli are grape-like clusters, each composed of a single layer of epithelial cells surrounding a central cavity.
• Epithelial cells absorb nutrients from the blood, transform them into milk, and discharge the milk into the cavity of the alveolus.
• Myoepithelial cells surround each alveolus, responsible for milk ejection during letdown.

Milk Let-Down Neuro-hormonal Reflex

• Suckling stimulus or massaging of the udder stimulates somatic nerves in the teat, sending a signal to the posterior pituitary gland.
• The posterior pituitary gland releases the hormone oxytocin, causing myoepithelial cells around the alveoli to contract.
• For efficient milking, important factors to remember include:
  • Stimulating 1 minute before milk let-down.
  • The maximal effect of oxytocin occurs during the first 2 to 3 minutes of milk let-down.
  • Stress during cow preparation or during milking will inhibit oxytocin release.

Udder Examination

• History includes cow, herd, housing, treatment, and clinical signs.
• Detailed examination of the udder includes:
  • Inspection of size, symmetry, shape, and lesions.
  • Palpation of teat, sinus, tissue, skin, and lymph nodes.
  • Evaluation of secretion, including look, smell, CMT, chemistry, and bacteriology.

Mastitis

• Mastitis affects profitability by:

  • Decreasing milk production (70% of total costs).
  • Causing milk to be dumped due to treatment.
  • Incurring veterinary and drug costs.
  • Increasing labor costs.
  • Resulting in culling and death losses.
  • Losing quality premiums.

• Health concerns of mastitis include:

  • Animal health: loss of functional quarter, lowered milk production, and death of cow.
  • Human health: poor quality milk and antibiotic residues in milk.

Causes of Mastitis

• Mastitis can be caused by various factors.

Milk Products

• Fermented and unfermented milk products include:
  • Sour cream: cultured and fermented by added lactic acid bacteria (18% fat).
  • Crème fraiche: slightly aged, cultured heavy cream (expensive).
  • Evaporated milk: milk with 60% of the water removed, having a cooked flavor.
  • Buttermilk: fresh liquid milk, usually skim, soured by bacteria.
  • Condensed milk: milk with 60% of the water removed, heavily sweetened with sugar (available in cans and bulk).
  • Yogurt: milk cultured by special bacteria, having a custard-like consistency (can be dried).
  • Dried whole milk: milk that has been dried to a powder.
  • Non-fat dry milk: skim milk that has been dried.

Other Products

• Whey: the watery part of milk after separation of the curd from the whole milk, containing protein, lactose, minerals, and salts.
• Cheese: the clotting casein of milk, made from separated milk or whole milk, and can be made through fermentation.
• Butter: solidified milk fat or cream, prepared by churning, and can be made into ghee by heating and clarifying.
• Ghee: butter that has been heated and clarified, with the water evaporated and then strained.

Physiochemical Properties of Milk

• Milk is a complex colloidal dispersion containing fat globules, casein micelles, and whey proteins in an aqueous solution of lactose, minerals, and other minor compounds.
• Major physical properties of milk include:
  • Color (white to yellow, depending on the carotene content of the fat).
  • Specific gravity and density.
  • Freezing point and boiling point.
• These properties are influenced by the composition of milk and are important in processing and testing milk for adulteration.
• Other properties include:
  • Viscosity.
  • pH.
  • Titratable acidity and acid-base equilibrium.
  • Electrical conductivity.