Much of the pedigree cattle breeding world is in a state of flux following a Defra ruling on Herd Books.

The implementation of the zootechnical legislation means that animals with myostatin or double muscle genes cannot be prevented from being registered. This has thrown a number of societies into disarray, as some members do not want the double muscle gene present in their breed’s pedigree.

Some societies have approached Defra to investigate altering the ruling.

However, the UK Government legislation mirrors rules in the EU, and any changes could impact the trade of genetics with the continent. At present, there is no live consultation however, Defra is considering options in relation to potential reform of the retained zootech legislation.

The rules are particularly challenging for breeds with concerns over the impact of myostatin genes, or double muscle genes. Some of these breeds are looking to prevent animals with the myostatin gene, identified through DNA tests, from being registered within the breed. However, under the new UK law, this would not be allowed, and the animals, if their parents are both registered within the Herd Book, must be accepted.

Defra’s guidance states: “As outlined in legislation, a breeding society is unable to refuse an animal entry into the main section of a Herd Book if it has its parents or grandparents already registered in the main section of a breeding book of the same breed.”

However, the rules do allow for these animals to be registered in separate classes within the Herd Book.

This could lead to some breeds being split into sections with pedigrees for identified double muscle genes and other sections for animals without the gene present.

This division could extend to separate sales or show classes for the different parts of the Herd Book.

According to Defra, the rules mean that breed societies can establish separate classes in the main section of the breeding book to support different criteria or procedures.

The government department states that there could be a separate class for ‘undesirable traits’ in that breed, such as the double myostatin or single myostatin gene. If this were to be enacted, then it could be required for a breed society to mandate a DNA test when registering an animal so that it can be determined which section of the Herd Book the animal will be registered in.

There is an area of the rules that can prevent animals from entering the Herd Nook if there are grounds for genetic defects, health issues, or welfare concerns. However, this has yet to be fully tested, with negotiations between some societies and Defra ongoing.

The double muscle or myostatin genes affect the ability of cattle to regulate muscle growth and has been found is extensive range of breeds.

Animals with the gene present have more muscle mass and higher meat yields; however, there is also potential for calving difficulties.

The impact of myostatin was discovered by academics Se-Jin Lee and Alexander McPherron in 1997, when they identified genes in mice that caused the rodents to increase by two or three times. Later that year, McPherron and Lee studied Piedmontese and Belgian Blue cattle, which were hypermuscular.