There is an ever-increasing trend toward the development of more specific genetic tests as the cattle genome is mapped.
It can be difficult for cattle producers, and especially purebred breeders, to decide which genetic tests will return economic return or improve their herds.
This economic return could be directly in the form of bull sales or perhaps a better class of cattle to build herds around.
Remember that most if not all of these genetic tests can be selected for naturally over time.
The test for polledness is an example. A producer could mate a bull to nine or 10 horned cows to determine if it is homozygous polled. There is literally a 99 percent chance the bull is homozygous polled if the offspring are all polled.
However, that method takes one year to discover results and the producer has already bought and used the bull. The same results can now be determined using a blood test and can be achieved before the producer buys the bull.
This test may be worth considering if having all polled cattle is an important part of a producer’s operation.
Costs have to be considered with all these tests. The polledness test now costs $100 and the lab that does it is in the United States, which means the blood must be sent by courier at an additional cost.
A few tests may be inconclusive and producers aren’t charged for them.
There are tests for colour to determine if black cattle are homozygous for black or are red carriers because black colour is dominant to red.
This could have an advantage for producers either way, depending on the colour and consistency of their herd.
Cost versus benefit must be taken into account, but this genetic test could give a producer an upper hand in the market.
Impeccable record keeping will eliminate the need to always test in the future. A homozygous black animal bred to another homozygous black will always yield a homozygous offspring, so there would be no need to test it in the future.
A test is available for the propensity to marble (the fat gene), which has garnered lots of interest lately. Animals that are carriers or homozygous for this gene have a greater likelihood to grade AAA, which could add value to the carcass.
This test was just surfacing as the BSE crisis hit, and a shortage of extra cash in the livestock sector meant it wasn’t adopted wholeheartedly at the time.
A genetic test for docility is in the works. Wild animals are more prone to injury, don’t grow as well and make the others in the pen hyper as well. Knowing this before animals are bought would be a big advantage.
Artificial insemination sires could have genetic profiles on all these tests, which would add more data from which to choose. One might argue that too much choice is confusing, but one can never have too much information. The cream of the genetically superior animals will rise to the top.
The U.S. dairy industry now tests for fertility, milk production without sacrificing fertility, red colour and a natural variation in the growth hormone bovine somatotrophin.
We know from natural selection that over-selecting for one trait can sacrifice other traits ,which must be avoided by selecting the right combination of genetic traits.
Health-care companies have entered the genomics market, and tests are already available. The discovery of new markers for specific traits is adding to their scope, and innovative products can be expected in the next few years.
The tests require blood, hair follicles, nasal swabs or semen.
Labs that perform the hair test make it easy for producers to collect the samples, and there are no issues of freezing or heating that can occur with blood.
The hair can also be mailed, which eliminates the expensive costs of couriers. Grouping samples together always makes shipping more efficient.
However, not all tests can be done on the follicles.
Purebred breeders in particular should talk to their veterinarian about which tests would be most appropriate for their herd. This forms a type of genetic counselling that veterinarians may offer.
Breed associations are always interested in genetic defects that could damage their breed’s reputation. The significant defects may be tested for and carriers eliminated.
However, the significance of the defect in relation to all the other costs of production must be considered before we get too brash. Proceed cautiously with all genetic decisions.
It is only a matter of time before more of these genetic tests are commercially used in Canada. Using them in combination with natural selection will help the demand for our seed stock flourish both domestically and abroad.
Roy Lewis has a veterinary practice in Westlock, Alta. and works part time as a technical services veterinarian with Merck Animal Health.