Milk production per cow
Which cows earn their feed, which are slipping, and which are carrying a high cell count. How the weight gets measured, what the numbers mean, and what it costs.
The short version. For a 40 to 300 cow herd without parlor meters, monthly DHIA testing is the answer. A technician weighs every cow's milk once a month and sends a sample to the lab. You get pounds, butterfat, protein, and somatic cell count for every cow, plus 305-day projections, for roughly $25 to $55 per cow per year. You do not need a weight at every milking.
Three ways to get a per-cow milk weight
| Method | How it works | Fits |
|---|---|---|
| DHIA test day | A technician, or you as an "owner-sampler," hangs portable meters on test day, records each cow's weight, and pulls a sample for the lab. Once a month or every 4 to 6 weeks. | Most conventional herds, 40 to 300 cows. The best value by far. |
| Permanent parlor meters or robots | Every milking is weighed automatically and lands in the equipment maker's software (DeLaval DelPro, GEA DairyPlan, BouMatic, Afimilk, Lely Horizon). | Herds with a modern parlor or robots. If you have these, the data already exists. Do not retype it. |
| Weigh jar or bucket scale | Divert one cow's milk and weigh it. Simple and cheap for a few cows. | Tie-stalls, fresh-cow pens, or checking one suspicious cow between tests. Too much labor for a whole herd above about 50 cows. |
A common misconception. Monthly test-day numbers are enough to see the lactation curve, catch chronic low producers, find high-cell cows, and decide who to cull or dry off. Daily weights only pay when they come from meters that already exist and someone acts on the alerts every day.
What DHIA gives you
- Test-day milk pounds for every cow, plus fat and protein percent and pounds, and somatic cell count (SCC).
- Days in milk, lactation number, projected 305-day milk, and mature-equivalent records for fair cow-to-cow comparison.
- Herd reports: fresh-cow list, dry-off list, cows over 200,000 SCC, which cows contribute most cells to the bulk tank, rolling herd average, and benchmarks against similar herds.
- A web portal and a monthly herd summary, often called the "202 sheet."
Cost. Planning range is about $2 to $5 per cow per test plus a stop charge, roughly $25 to $55 per cow per year. Penn State Extension cites about $25 per cow per year. Every-other-month testing is cheaper. Get a written quote from your local affiliate: Dairy One in the Northeast, AgSource in the upper Midwest, Lancaster DHIA in Pennsylvania, or the regional DHIA for your state.
How to read the numbers
Always compare cows within the same lactation number and stage. A first-calf heifer at 70 days in milk and a fourth-lactation cow at 240 days should never be ranked against each other. Group as first lactation vs. mature, and fresh (0 to 30 days), early (31 to 100), mid (101 to 200), late (over 200).
| Term | What it means and what to look for |
|---|---|
| Peak milk | Highest test-day weight in the lactation. First-lactation cows peak around 50 to 90 days in milk; mature cows around 45 to 70. A mature cow that never rises after calving needs a transition-cow look: intake, ketosis, crowding. |
| Persistency | How well a cow holds milk after peak. This month divided by last month. Mature cows typically lose 7 to 10% per month after peak; heifers 4 to 7%. A whole-group drop means feed, heat, or facility. A one-cow drop means health, feet, mastitis, or a wrong ID. |
| 305-day, actual or projected | Lactation total standardized to 305 days. A projection is an estimate, not milk sold. Reliability improves as tests accumulate. |
| Mature equivalent (ME) | Adjusts for age so a heifer can be compared to a mature cow. Use for comparing and breeding decisions, never for cash flow. |
| Rolling herd average | Herd production over the past 12 months. Moves slowly. Good for direction, useless for catching this month's problem. |
| SCC and linear score | 200,000 cells/mL or higher suggests an infected quarter. The legal Grade A limit is 750,000. Linear score doubles with each doubling of SCC: 100k = 3, 200k = 4, 400k = 5, 800k = 6. Watch new infections (was low, now high) and chronics (high two tests in a row). |
Calculators
Everything runs on your phone. Nothing you type here is sent anywhere.
Five things to check every month
- Test-day milk by lactation group and stage. Look for group changes before individual outliers.
- Peak or "summit" milk by lactation group. Tells you whether fresh cows are transitioning well.
- Persistency. This test vs. last test, by group.
- Shipped vs. test-day comparison. Penn State's rule: if bulk-tank pounds and the sum of test-day weights differ by more than 5%, something is wrong. Withheld milk, or bad weights.
- SCC. Percent of cows over 200,000, new infections, chronics, and the top contributors to the tank.
Decisions the records drive
- Culling. Never on one low test. Check the ID, days in milk, pregnancy, SCC history, feet, and what she earns over feed cost. A pregnant, healthy, late-lactation cow may deserve to stay at low milk. A high-producing chronic mastitis cow may be the expensive one.
- Dry-off. Set by expected calving date: 45 to 60 days dry. If she is still at 45 to 55 lb near dry-off, ask the vet and nutritionist how to take her down.
- Feeding groups. Move cows on two tests, not one. Frequent pen moves cost intake.
- Mastitis. Culture the chronic and new-infection cows rather than treating every high SCC.
Tools, cheapest to most expensive
| Tool | Rough cost | Notes |
|---|---|---|
| Paper or spreadsheet | $0 | Fine for 20 to 100 cows if one person owns it. Two sheets: a cow list, and one row per cow per test day. |
| Cattly, DairyFarmManager, Zisk | Free tiers | Phone apps that store per-cow milk. Check that they export your data as a file before relying on one. |
| CattleMax, Herdwatch | $9 to $30/month | Good for IDs, treatments, breeding. Weak on dairy analysis (no lactation curves or 305-day math). |
| Farmbrite | $29+/month | One app for cows and fields. Shallower on dairy than the DHIA tools. |
| PCDART (DRMS) or DHI-Plus (Amelicor) | $300 to $1,500/year, often bundled with DHIA | The dairy-specific programs that come with your DHIA records. Best value for 40 to 500 cows on test. |
| BoviSync | About $1 to $4 per cow per month | Task lists, protocols, employee workflows. More than a family herd needs. |
| DairyComp 305 | About $1,500 to $6,000/year | The big commercial-dairy database. Powerful, steep learning curve. |
Prices are 2026 planning ranges from vendor pages and third-party listings. Vendors change plans often. Confirm before buying.
If you have no meters and 40 to 200 cows: join monthly DHIA, order milk, fat, protein, and SCC, use the PCDART or DHI-Plus option if your affiliate offers it, and keep a spreadsheet between tests. Fix your cow IDs first: one permanent number per cow, never reused. That is the whole recommendation.
Common mistakes
- Ranking cows without accounting for days in milk and lactation number.
- Culling on one low test.
- Buying meters before fixing cow IDs.
- Assuming the robot's conductivity alert is an SCC.
- Looking at fat percent instead of fat pounds.
- Treating projected 305-day or ME as milk sold.
- Doubling the AM milking to get a daily total.
- Recording milk but not fresh date, events, or pregnancy.
- Saving data nobody reviews.
Questions for your DHIA technician
Which test plan fits us? Can you audit our cow IDs? Which reports show 305-day, ME, days-in-milk groups, and SCC exceptions? Can I get the data as a spreadsheet? What are the 2026 fees? Who owns the records if we switch?
Free resources
- Penn State Extension, Dairy: "Analyzing the 202," "Evaluating milk peak and persistency using DHIA data," "Income over feed cost." extension.psu.edu/animals-and-livestock/dairy
- National DHIA, DRMS, Dairy One, AgSource: find your local affiliate, testing plans, PCDART. dhia.org · drms.org · dairyone.com · agsource.com
- National Mastitis Council: SCC interpretation, sampling, mastitis control. nmconline.org
Printable PDF of both guides Go to yield per field →
Tell us what you think
Do you get per-cow weights today, and how? What did we get wrong? What would help that isn't here?