Milk release in mammals is hormonally regulated, which is also the case in dairy cows. The cow will start to release milk when the hormonal conditions that control this process are as optimal as possible.
A short moment prior to milking, approximately 80% of the milk present in the udder is stored in alveoli and small milk ducts.
Correct pre-treatment of the udder (in terms of both technique and timing) sends a signal from the cow's brain to the pituitary gland, triggering the release of oxytocin. Via the bloodstream, oxytocin “travels” to the smooth muscle cells surrounding the alveoli and causes them to contract. These contractions release the milk for the calf or the milking machine.
HOW DOES STRESS AFFECT MILK RELEASE?
Stress factors (not exhaustive), such as pain, fear, and/or welfare issues, trigger the brain to release adrenaline and cortisol. Adrenaline (and Noradrenaline) blocks the release and activity of oxytocin.
It is the natural counterpart; where oxytocin promotes tranquility, adrenaline creates stress as a natural survival mechanism.
With regard to stress, cortisol puts the body on high alert, increasing alertness and responsiveness.
STRESS FACTORS BEFORE AND DURING MILKING
- Various working practices by various employees: Cows are autistic, and autistic individuals prefer calm and regularity. It is therefore important to work according to set protocols.
- Moving cows from the cubicles to the milking parlor: cows in the cubicles often refuse to get up if there are cows standing behind them on the slatted floor.
- Slippery slatted floors, dark shadows in the barn, and changes in flooring material: cows do NOT get used to these.
- “Drafts on their heads”.
- Overcrowded waiting areas: (where “overcrowded” means the cows are packed tightly together, with their heads facing upwards).
- Heat stress: both in the barn but especially in the waiting area and during the milking process.
- Inadequate lighting for cows in the milking parlour and/or the waiting/collecting area.
- Obstacles near the milking robot.
- Disturbing music and other disruptive (mechanical) noises in and around the milking parlor.
- Shouting, screaming, and staff moving back and forth frequently while herding and during the milking process.
- Incorrectly adjusted milking equipment.
Source text and photo: Ronald Rongen