Genomic Testing in Dairy Heifers

Genomic testing reads a small tissue or hair sample to predict a heifer's genetic merit while she is still young. It helps you decide which animals to keep, breed and invest in.

Key points

Genomic tests predict genetic merit using a small sample.
They help with replacement, breeding and parentage decisions.
Testing pays only if it changes what you do.
Keep identification and sample records exact.
Good calf care is still needed to reach genetic potential.

What a genomic test is

A sample, often a small piece of ear tissue, hair with the root or a blood spot, is sent to a laboratory. The lab reads genetic markers and compares them with large reference data. The result is a set of predicted breeding values and sometimes information about inherited conditions and parentage.

These predictions are more reliable than a pedigree average alone, but they are still predictions. They describe expected genetic merit, not what she will do in your barn.

Different labs and different tests report different things. Some give a basic panel and others a fuller set of traits. Ask which one matches the decisions you plan to make instead of paying for information you will not use.

How herds use the results

Common uses include ranking heifers to decide which to keep as replacements, choosing which to breed to sexed semen or to beef, verifying parentage and finding animals that carry known genetic conditions.

Herds with more heifers than they need often use the ranking to sell or breed the lowest group differently. Herds that are short of replacements may use it to protect their best animals.

Results are most useful when everyone knows the rules ahead of time. Decide before the results arrive what you will do with the top, middle and bottom groups, and write it down. That prevents second-guessing once the numbers are in front of you.

Rank heifers for replacement decisions
Choose which heifers to breed to sexed or beef semen
Check parentage records
Identify carriers of known conditions

When to sample

Many farms sample calves early, so decisions can be made before much feed has been spent. Ask your lab and your adviser about sample handling, timing and labeling. A mislabeled sample wastes the cost and gives a result for the wrong animal.

Make sampling part of the calf routine. Put the identification, the sample and the record together every time.

Calf health comes first. Sample in a way your veterinarian is comfortable with, keep tools clean and handle calves calmly. If a calf is sick, ask your vet whether sampling should wait.

Cost, value and fit

Testing has a cost per animal. Whether it pays depends on how you use the results. If you will not change any decision, testing adds cost without benefit. If it changes which heifers you raise or how you breed them, it can pay.

Ask your adviser to help you work out a plan using your own costs of raising heifers and your own replacement needs. Prices and services change, so ask labs and providers for current terms.

Records and data

Keep the results with the animal's record. Link each test to the animal's ID, birth date, dam and sire. Know who owns the data and how it can be shared. Ask the lab how results are returned and whether they can be loaded into your herd software.

Make sure everyone who handles calves knows how identification is kept straight.

Back up the records. A spreadsheet that lives on one computer can disappear, and results are hard to recreate. Keep a printed or digital copy somewhere separate from your herd software.

Matching ID tags and sample IDs
One person responsible for sampling
Results filed with the animal record
Clear terms on data ownership

Questions to ask a lab or adviser

Ask how reliable the results are for your breed and herd, what traits are reported, how long results take and what happens if a sample fails.

Ask how the results will fit your sire choices and your plan for beef or sexed semen.

Ask for a sample report so you can see how results are shown before you commit. Ask also how the lab handles lost or damaged samples and whether there is a retest policy.

Common mistakes

Testing without a plan for the results, mislabeling samples, treating a prediction as a promise and ignoring calf care are the usual problems. A heifer with good genetics still needs good colostrum, nutrition and health to reach her potential.

Review results with your adviser once a year and see if your decisions are better than before.

When to get help: Ask your AI representative, breed association or extension dairy specialist to help you plan a testing program. Your veterinarian can advise on safe sampling methods for calves.

Sources and further reading

Organization homepages are linked so you can search them for current guidance on this topic.

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