Myostatin and the suckler herd: what every beef farmer needs to know

An understanding of the myostatin gene can help producers to make informed decisions about their suckler herd breeding programme.

Growing discussion around myostatin genetics is influencing breeding decisions on farms across Northern Ireland, with producers urged to better understand how different gene mutations can impact profitability, animal welfare and labour demands.

The College of Agriculture, Food and Rural Enterprise (CAFRE) says improved awareness of myostatin can help farmers align breeding strategies with the specific goals of their suckler enterprises.

CAFRE Beef and Sheep Adviser John Hamilton said interest in the topic has increased significantly in recent years.

“In recent years talk of myostatin has grown steadily around show and sale rings with many farmers turning to it as a valuable aid in selecting replacement breeding stock.”

CAFRE Beef and Sheep Adviser John Hamilton 

What is myostatin?

Myostatin is a gene responsible for regulating muscle growth in cattle. When functioning normally, it controls the amount of muscle an animal develops. However, certain mutations or physical breaks in the gene reduce this control, allowing muscle growth to accelerate.

Teagasc Geneticist Dr Cliona Ryan has previously likened the gene’s role to a braking system on muscle development. When the “brake” is weakened, animals can develop heavier muscling.

While this can be desirable in some breeding systems, it can also present challenges, particularly for commercial suckler herds focused on calving ease and efficiency.

Different goals, different outcomes

The impact of myostatin mutations depends largely on a farm’s breeding objectives.

Producers breeding heavily muscled, show-type cattle may favour animals carrying specific myostatin mutations to achieve enhanced conformation. However, these farmers often accept the increased management demands that can accompany such traits.

For many commercial producers, priorities differ. Calving ease, growth rates and reduced labour input are often favoured over extreme muscling. These farmers may opt for animals with mutations that do not negatively affect these traits, or animals that are entirely free from myostatin mutations.

Common myostatin mutations explained

At a recent Business Sustainability Group (BSG) suckler meeting, Mr Hamilton outlined the most common myostatin mutations found across popular beef breeds.

These include F94L, Q204X and nt821.

The F94L mutation, often referred to as “the profit gene”, can improve muscling without significantly increasing calving difficulty.

In contrast, Q204X and nt821 mutations are associated with improved muscling, better conformation and higher killing-out percentages. However, they can also, on occasion, result in increased birthweights, calving difficulties and additional management challenges that require greater labour input.

Animals without any myostatin mutations will display the natural traits typical of their breed, without enhanced muscling.

Passing traits to the next generation

Cattle may carry either one or two copies of a myostatin mutation.

Animals with two copies, known as homozygous, will always pass a copy of that mutation to their offspring. Animals with one copy are described as heterozygous and have a 50-50 chance of passing the mutation on.

Some heterozygous animals may carry two different mutations, meaning either could be passed to progeny, adding another layer of complexity to breeding decisions.

Knowledge that supports better decisions

CAFRE says improved understanding of myostatin genetics can support better herd management, helping producers match breeding strategies to the realities of their production systems.

In conclusion, a greater understanding of myostatin mutations can greatly enhance management decisions on farm. By applying this knowledge, producers can make more informed choices and tailor breeding strategies to align with the specific goals of their enterprise.

Farmers seeking further advice on beef breeding management are encouraged to contact their local CAFRE Adviser.