Milk Production, Lactation and Milking Hygiene
Domain 2 examines the lactation cycle, milk let-down, milking routine and udder hygiene. Questions often ask you to sequence pre-milking and post-milking steps or interpret a lactation curve.
Core rules
- Colostrum is the first 3-5 days' secretion, rich in antibodies; it is not saleable normal milk.
- Milk let-down is a neuroendocrine reflex; oxytocin acts within 30-60 seconds, so attach the milking unit promptly and avoid stress.
- Wash and dry the udder, discard foremilk, check for mastitis, milk completely, then dip teats. Keep cows standing for about 30 minutes after milking.
- Lactation length is about 305 days, followed by a dry period of about 60 days. Machine milking needs correct vacuum and pulsation.
Worked example
A cow peaks at 12 L/day and has a monthly persistency of 85%. After 3 months: 12 × 0.85 × 0.85 × 0.85 = 12 × 0.614 = 7.37 L/day. The reasoning is that persistency is applied multiplicatively each month, not subtracted as a fixed 15% of the peak.
Traps
- Milking a wet udder spreads dirt and bacteria.
- Incomplete milking lowers yield and raises mastitis risk.
- Discarding foremilk is a hygiene check, not waste.
- Colostrum is not the same as transition milk or normal milk; feeding it to calves is beneficial but selling it is not allowed as normal milk.