Understanding Milk Yield Trends — What Your Cows Are Telling You

Your cows are talking. Every morning and every evening, the amount of milk they give is a signal — a data point that, when combined with yesterday's and last week's, tells you exactly what is happening on your farm.

But most farmers only see one number at a time. "Nyambura gave 14 litres this morning." Good or bad? You do not know unless you can compare it to her 7-day average, her stage of lactation, and the rest of the herd.

Here is how to read milk yield trends like a manager, not just a milker.

The lactation curve: what normal looks like

Every cow follows a predictable production pattern after calving:

Weeks 1–2: Production rises rapidly. The cow is not yet at peak but she is climbing. Yield increases by 1–2 litres per day.

Weeks 3–8: Peak lactation. This is the highest production your cow will achieve in this cycle. For Friesians in Kenya, peak is typically 18–25 litres per day. For Jerseys, 12–18 litres. For crosses, it varies widely.

Weeks 8–40: Gradual decline. Production drops by about 2.5% per week. This is normal. A cow producing 20 litres at peak will produce roughly 15 litres at week 20 and 10 litres at week 40.

Week 40+: If still milking and not dried off, production drops more sharply. Most cows should be dried off by week 44–48 (around 305 days in milk).

When your records show a cow following this curve — rising, peaking, then gently declining — everything is working. Worry when the curve breaks.

Red flag 1: sudden drop

A cow producing 16 litres yesterday gives 11 litres today. That is a 30% drop overnight. Something happened.

Possible causes:

Illness — mastitis, fever, digestive upset. Check for swollen quarters, lumpy milk, loss of appetite, elevated temperature.
Feed change — did you switch feed suppliers, run out of concentrates, or change the roughage? Cows react to abrupt feed changes within 24–48 hours.
Water restriction — a cow that does not drink enough produces less milk immediately. Check water troughs.
Stress — new herdsman, aggressive herd-mate, construction noise, transport. Stress suppresses let-down.
Measurement error — before panicking, confirm the measurement is accurate. Was the bucket calibrated? Was milk left in the udder?

Action: A single day's drop might be measurement noise. Two consecutive days at the lower level means something real is happening. Investigate.

Red flag 2: gradual decline faster than expected

Your 7-day averages show a cow dropping 3 litres per week instead of the normal 0.5 litres per week decline. She is not sick — no temperature, eating well, normal milk. But production is falling faster than her lactation stage justifies.

Possible causes:

Subclinical mastitis — infection without visible symptoms. The somatic cell count is elevated but the milk looks normal. This quietly destroys yield.
Inadequate nutrition — she is in negative energy balance longer than she should be. Common in early lactation when feed quality or quantity does not match the cow's demand.
Pregnancy — if she was successfully bred, pregnancy begins to redirect energy from milk to the calf around month 5. This is normal and expected.
Heat stress — during hot dry season in Kenya, cows reduce production. This affects the whole herd, not just one animal.

Action: If only one cow is declining faster than the herd, investigate that individual. If the whole herd is declining faster than expected, look at feed or environment.

Red flag 3: no peak after calving

A cow calved two weeks ago. She is at 10 litres. Three weeks ago, she was at 10 litres. She never climbed.

Possible causes:

Calving complications — retained placenta, milk fever, or other post-calving issues that were not fully resolved.
Poor transition feeding — the cow was not given adequate nutrition in the last 3 weeks before calving and the first 3 weeks after. Her body did not have the energy reserves to ramp up.
First-calf heifer — heifers produce 20–30% less than mature cows in their first lactation. If this is her first calf, a lower peak is normal.
Genetics — some cows simply have lower genetic potential. If her dam was also a low producer, you may be seeing a genetic ceiling.

Action: If management and health are not the issue, this cow's genetics may limit her. Track her full lactation before deciding whether to breed her again or cull.

The herd average tells you about management

Individual cow data tells you about that cow. But the herd average tells you about your farm management.

If your herd average is 12 litres and your neighbour's herd of similar breed and age averages 16 litres, the difference is management: feed, health care, breeding decisions, and milking practices.

Track your herd average weekly. A rising herd average means your management is improving. A falling average means something system-wide needs attention.

Comparing morning to evening

Most cows produce about 55–60% of their daily yield in the morning session and 40–45% in the evening. This is normal — the overnight interval is longer.

If the ratio shifts — say, evening yield drops to 30% of the daily total — investigate:

Is the evening milking on time? Delayed milking reduces yield.
Is the herdsman milking completely? Incomplete milking trains the udder to produce less.
Is there feed available between sessions? A cow that runs out of roughage by noon will produce less in the evening.

Day-of-week patterns

Some farms show consistent dips on specific days. Monday production is lower because weekend management was different. Or Friday is lower because the herdsman leaves early.

These patterns are invisible in a notebook but obvious on a weekly chart. They point to management inconsistencies that you can fix.

Using trends for breeding decisions

A cow at 150 days in milk, producing 10 litres per day and declining normally, is a good candidate for breeding. Her next calving will be timed to keep her productive.

A cow at 150 days in milk, producing 6 litres per day and declining faster than expected, may not be worth the cost of another AI straw and 9 months of gestation. The data helps you make this call objectively.

The 7-day average is your best friend

Daily yield fluctuates. One low day does not mean a problem. One high day does not mean a cure.

The 7-day rolling average smooths out daily noise and shows the true trend. When the 7-day average drops for two consecutive weeks, something real is happening. When it rises, something good is working.

Make the 7-day average the number you check, not the daily number.

Your milk yield is a conversation. Start listening at shira.farm.