Genetics

Inherited bovine diseases – are there options for management?

Genetics editor Alastair Rayner 13/08/2024

 

WITHIN any bull sale catalogue there is an increasingly detailed level of information on offer to prospective purchasers. While most attention is given to performance records and pedigree, many producers are now also focussed on information regarding known genetic disorders.

In some cases, this information is essential to avoid introducing a known issue to a herd, while for others the information is valuable in making a considered selection decision to find a bull that could be used for a specific purpose with a particular group of females.

However, genetic disorders are not always front of mind for every producer. Many commercial producers may not consider genetic disease or disorder an issue. In some circumstances this approach may be a valid position. At the same time there is a very large potential for producers to be impacted by genetic disorders, resulting in noticeable production losses or even adverse welfare outcomes.

600 conditions reported in cattle

Genetic disorders are not necessarily uncommon in cattle. There have been more than 600 different conditions reported in cattle.

Around 45pc of these are the result of a genetic mutation in a single gene. The practical implication of this is that the causal mutation can be identified through DNA analysis and then managed on the basis of DNA tests.

Currently causal mutations have been identified for more than 180 inherited diseases in cattle. The increasing use of DNA testing as well as the increased availability of testing options for producers does mean there is much greater opportunity to manage genetic disorders in a herd.

One of the greatest challenges in managing genetic conditions within commercial herds lies in recognition of the problem.

Some conditions are often not immediately identified or are mistaken for other issues. Poor growth rates are often first associated with nutrition, or a dam’s maternal ability. Other conditions result in early death as they can prevent calves from standing and suckling after birth. Those calves missing at marking are often considered to be lost due to poor mothering, predation or misadventure.

Often these non-specific losses or lower production levels occur in beef enterprises but are not generally associated with genetic conditions. As a result, many producers may think they have no issues within their herd, and consequently the impact of the condition becomes more prevalent and entrenched within a herd. This is often the case with conditions that are caused by single gene mutations.

Most of the inherited diseases impacting beef production have a recessive mode of inheritance. There are three possible genotypes that can exist because of recessive genes:

  • The first is Free, where an animal has two normal alleles and no copies of the mutation
  • The second is known as a Carrier animal. These animals look normal, but they carry one copy of the mutation which can be passed onto their progeny
  • The final type is known as Affected. These animals have two copies of the mutation.

Source: ABRI Conditions – Possible mating outcomes for a recessive condition

New information hub

From a management perspective there are some strategies producers can consider to address genetic conditions. Firstly, it is important to determine if genetic conditions are a cause of unexplained losses or contributing to lower levels of production.

The University of Sydney has recently established the Anstee Hub for Inherited Disease of Animals (AHIDA). This development provides producers and veterinarians with an online method of reporting suspected conditions. Reports to AHIDA can be made anonymously to contribute to surveillance data or by registering with AHIDA, if the submitter would like to receive advice or would like to contribute to research.

The online platform allows producers to report their concerns and potentially connect with researchers who may be interested in investigating the issue

Traditionally, producers may have engaged only with their vet to determine the causes of unexplained losses or production. However, as noted previously, some producers may not have considered genetic conditions, or in extensive regions may not be across the scale of loss.

The release of AHIDA as an online platform allows producers to report their concerns and potentially connect with researchers who may be interested in investigating the issue.

As a method of developing a clearer picture of genetic conditions nationally, producers should consider submitting data if they suspect that an inherited disease contributes to health problems or production losses in their herd. This will provide information about how common the known inherited diseases are in the Australian cattle population and will raise awareness about emerging inherited diseases that need to be investigated to develop DNA diagnostics.

Aside from reporting, management falls into decisions around the incidence of affected animals and management of carrier animals. For a recessive disease, birth of affected animals can be avoided if at least one parent has two normal copies of the gene.

In commercial herds it may be impractical to DNA-test enough to accurately determine status of all animals. Some producers have tested samples of the herd to establish a base line. Their focus then falls onto seeking bulls that are tested as Free of known conditions. There are producers who may choose to purchase Carrier bulls, but these should only be joined to animals known as Free of the condition.

As the spring bull selling season continues across eastern Australia, producers should make sure they look at the information in the catalogue. Unless there is a deal of confidence in the genetic status of the breeder herd, preference should be given to bulls tested Free of known conditions.

When calving season begins, it will also be worth taking note of the unexplained losses and reporting these events through the AHIDA.

 

For more information on the Anstee Hub for Inherited Diseases in Animals click here,  or scan this QR code

 

Author Alastair Rayner is the General Manager of Extension & Operations with Cibo Labs and Principal of RaynerAg.  Alastair has over 28 years’ experience advising beef producers & graziers across Australia.   He can be contacted here or through his website www.raynerag.com.au

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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