Culling Decisions That Pay: Using Health, Fertility, and Production Data Together

Culling is one of the most consequential routine decisions on a dairy, and it is often made in a hurry. A cow is open, lame or low in the bulk tank, and the question gets answered by whoever is staring at her that day. Better decisions come from looking at several kinds of data together. This guide explains how to organize that data, what published figures say about why cows leave herds, and how to build a simple, consistent approach. It is general information; your veterinarian, nutritionist and DHI supervisor should help you adapt it. Related programs and advisors can be found through agriculture.directory.

What the numbers say about why cows leave

Penn State Extension's cull rate benchmarking article summarizes USDA survey data from the Northeast. The survey reported an average of 31.4 percent of cows culled plus a 6.2 percent death rate, for 37.6 percent of cows permanently removed in a year. Of the cows culled, 26.8 percent left voluntarily and 73.2 percent left for involuntary reasons.

Within those categories, the biggest reasons were:

• Poor production: 18.3 percent of culls, the largest voluntary reason.
• Infertility: 23.3 percent, the largest single involuntary reason.
• Mastitis: 18.6 percent.
• Lameness: 9.1 percent.
• Death: 6.2 percent.

Disease-related culls, including mastitis, lameness, metritis, displaced abomasum, respiratory disease and injuries, made up nearly 40 percent of biological culls. In other words, most cows do not leave because they produce a little less than their pen mates. They leave because something about their health or fertility failed. The same article notes that half of all culled cows were removed during their first two lactations.

Why production alone misleads

A cow with a strong 305-day record can still be a poor investment if she had a difficult freshening, three cases of mastitis or four services per conception. Conversely, a moderate producer that conceives on the first service, stays sound and keeps a low somatic cell count can be profitable for years.

The economics reinforce this. The Penn State article cites estimates that one clinical mastitis case costs about $325 in first lactation and $426 in later lactations, that milk loss from a retained placenta is about $130 and from a displaced abomasum about $280. It also notes that average productive life is around 2.7 lactations, and that recouping heifer-raising costs of roughly $2,000 takes more than three lactations. Those figures are estimates from the literature, and your own costs will differ, but the pattern is clear: a cow that leaves early often never repays her rearing cost. See our heifer raising guide for how that investment builds up.

Three data streams to combine

Production

Look at current milk, components and the trend, not only the peak. A cow that is dropping faster than her pen mates, relative to her days in milk, deserves attention. DHI records are the usual source, and our DHI basics guide explains the columns.

Health history

Count clinical mastitis cases, lameness events, metritis, displaced abomasum, and treatments. Combine this with somatic cell count history from monthly tests. Our mastitis guide and lameness guide explain the causes behind the records, and the Merck Veterinary Manual is a reliable reference for the diseases themselves.

Fertility

Track days open, services per conception, and any pregnancy losses. Infertility is the largest involuntary reason for culling in the survey above, so it deserves the most attention. For breeding tools, see the heat detection guide.

A simple scoring approach

Many herds find it helpful to rate each open or problem cow on a few factors rather than making a single gut call. One example, offered as a starting point, not a standard:

1. Is she pregnant, or is there a realistic chance of getting her pregnant soon?
2. Is her milk now below what her stall and feed are worth?
3. How many disease events has she had this lactation, and are they likely to recur?
4. Is her somatic cell count persistently high, and is she a risk to the bulk tank?
5. How does she compare with the heifers waiting to replace her?

The last question matters. Culling a cow only makes sense if the animal replacing her is expected to do better, and in some periods heifers are scarce or expensive. A herd that is short on replacements may keep more marginal cows. A herd with surplus heifers may cull harder. The Penn State article also warns that herds with over 40 percent first-lactation animals may lose milk yield, since younger cows typically produce less, which is a reminder that very fast turnover has a cost.

Timing matters

Penn State's summary reports that culls before 60 days in milk carry the greatest economic loss, and that more than half of deaths in the survey happened before 50 days in milk. That points to the transition period, not the late-lactation cow, as the place to prevent losses. Our transition cow guide covers the practical side.

Voluntary culls: use them to improve the herd

Because only about a quarter of culls in the survey were voluntary, a herd has limited control over who leaves. Voluntary culling is the chance to shape the herd. Using genomic information, as described in our guide on genomic testing and net merit, can help decide which heifers to keep and which cows to breed to beef, as covered in the beef-on-dairy guide.

Keep it consistent

The best culling system is the one you actually use every month. Review a short list of problem cows with your veterinarian, record the reason for every exit and revisit the reasons quarterly. If infertility dominates, look at heat detection and nutrition. If mastitis dominates, look at milking routine and housing. For a lighter read on what cows earn, see farm.fm's tongue-in-cheek piece on production. And always involve your veterinarian when health problems are part of the decision.