Storage Sites of Milk in Animals

Storage site(s) of milk in animals include:

Correct Answer: Alveoli, Glands and Cisterns

Milk is stored in all three compartments: alveoli, glands (ducts), and cisterns within the mammary gland. However, the proportion varies significantly between species.

Proportion of Milk in Cistern vs. Alveoli (Cistern:Alveolus ratio)

• Goat: 80:20 → 80% in cistern (can be milked anytime — no oxytocin reflex needed)
• Sheep: 50:50
• Cattle: 30:70
• Buffalo and Camel: 5:95 (mostly in alveoli)
• Sow: 0:100 (all in alveoli)

Clinical Significance

• Goats store 80% milk in cisterns — this is why milk can be drawn at any time from goats without oxytocin reflex/let-down stimulus.
• Sows store all milk in alveoli — piglets must constantly stimulate the udder for milk let-down.
• Residual milk (left after normal milking) is mainly in alveoli — requires oxytocin injection or re-milking to obtain.