Genomic Testing & Selection Resources for Beef Cattle

Fact Sheets

Brief guides for collecting tissue, hair, and blood samples for genetic testing in beef cattle, and interpreting results from genetic tests.

Sample Collection Guide

Methods for Sample Collection

Tissue Sampling Units (TSUs)

Tissue sampling units, or TSUs, punch a small tissue sample from the ear into a tube with preservation solution.

This sampling procedure can be combined with tagging, when the sample is taken at the same time as the tag is inserted into the ear.

TSUs can be stored at room temperature in a cool, dry place before shipping at room temperature.

Whole Blood and Blood Cards

Blood can be collected from a tail or jugular draw into a purple top tube (containing EDTA to prevent clotting). Whole blood should be stored in the fridge and shipped within a few days on ice packs.

Blood can also be spotted onto a FTA blood card covering the entire circle or square on the card, and be sure to let the card dry before storing in a cool, dry place.

Blood cards can be shipped at room temperature.

Hair Bulbs

Hair should be pulled and not clipped from the animal. First, comb out dirt and loose hairs from the area.

Next, use a clean tool such as pliers to pull 20-30 hairs (about width of a pencil) from the tail switch, poll, or neck area. Make sure to get the hair bulbs or roots, as these contain the DNA. Hair can be stored in a cool, dry location and shipped at room temperature.

Sampling Tips

Keep detailed and clear records during sampling to prevent duplicated or skipped animals. Make sure samples are not contaminated with manure, dirt, and debris.

Clean sampling tools between animals to prevent cross-contamination of DNA.

Store samples out of sunlight and heat, and ship accordingly to prevent DNA degradation.

Genomic Testing in Beef Cattle at a Glance

Parentage

Sire and dam IDs are matched and directly reported with offspring IDs, such as listed in the table below:

Single-Gene Tests

Single-gene or single-SNP tests are reported as a genotype represented by a number (0,0 or 0,1 etc.) or letters H/H, H/h, or h/h for polled/horned). An example is listed in the table below:

Genomic Expected Progeny Differences (GEPDs)

Values are often reported as an animal’s deviation from the breed mean (+/-), which is not necessarily 0. An example is shown in the table below

Accuracy (ACC) is how likely the prediction is to match the true value, which increases with more information from progeny and genetic testing.

Percent rank (% RANK) represents an animal’s ranking among others within a breed.

Depending on the genomic test, some GEPDs are reported as scores from low to high (1-10). An example is shown in the table below.

Selection Indices

Selection indices are reported most often as dollar ($) values above breed average with percentile rankings for each animal. Some selection indices are breed-specific and cannot be compared or will need adjusting to compare across breeds. There are also indices specifically designed for crossbred animals. An example comparison of selection indices between two bulls is listed below.

GEPD and Index Terminology Key

Some general GEPD and index definitions for beef cattle are listed below. Which values are reported may differ by breed and specific genomic test.