Bovidae Anatomy · Interactive Diagram

Cow Mammary System
Udder, Teats & Milking

Click & drag down on a teat to milk

Collected 0 mL

Four-quarter udder

The cow's udder is divided into four quarters, each functioning as an independent mammary gland with its own teat, cistern, and duct system.

Let-down reflex

Tactile stimulation of teats triggers oxytocin release from the pituitary gland, causing myoepithelial cells around alveoli to contract and eject milk into the cisterns.

Milking technique

The teat is trapped between thumb and forefinger, then squeezed sequentially downward to push milk through the streak canal. Never pull — compress.

Production capacity

A Holstein dairy cow produces 25–35 liters per day across 2–3 milkings. Peak production occurs 4–8 weeks after calving, sustained through a ~305-day lactation cycle.

Milk Profile

3.5–5%

Fat

3–3.5%

Protein

4.7–4.9%

Lactose

~650 kcal/L

Energy

Calf Nursing Bout

~2 L

4-6 times daily

~1,300 kcal per bout

Human Serving

240 mL

1 standard cup

~156 kcal per cup

Taste & Texture

Mild, slightly sweet, creamy. Holstein milk is thinner (lower fat) while Jersey or Guernsey milk is richer and more golden due to higher beta-carotene content.

Nutritional Notes

Excellent calcium source (~120 mg/100mL). Contains casein and whey proteins in roughly 80:20 ratio. A1 vs A2 beta-casein variants affect digestibility for some individuals.

Minerals & Vitamins

Rich in riboflavin (B2), B12, phosphorus, and potassium. Contains fat-soluble vitamins A, D, E, and K. Iodine content varies with feed and season.

Unique Properties

Most widely consumed animal milk globally. Fat globules are relatively large, allowing natural cream separation. Homogenization breaks these down for uniform texture. Contains over 400 different fatty acids.