Unwanted mutations in Norwegian sheep

Janne Karin Brodin

As lamb-eating consumers, most of us prefer getting to grips with a large, meaty steak of lamb. Three mutations which all give meaty lamb carcasses with little fat have been identified in Norwegian sheep. One mutation is alrady known from the Texel race, whereas the two others are recently discovered ”Norwegian” mutations

However, what at first glance may be seen as a positive effect, has for one of the Norwegian mutations been found to lead to increased lamb mortality, hence this mutation is unwanted. The genetic bases for some lambs turning out extremely meaty, and the consequences of using these animals for breeding, is the main theme in Inger Anne Boman’s PhD thesis.

Inger Anne Boman Photo: Janne Brodin

Production advisors and sheep farmers have for a long time registered that some lambs turn out extremely meaty. This phenomenon has been known in Norway since 1939, but only recently has it become possible to chart the genetic background for this trait.

In search of genes
One mutation was found in the race Norwegian White Sheep (NWS), and another one in Norwegian Spælsau. Both mutations were found in the so called myostatin gene. As it turns out, a mutation of the myostatin gene had been found in Belgium, in the Texel race. Consequently, the Norwegian sheep included in this study were tested also for this mutation.

Positive as well as negative effects
The effect of these mutations in Norwegian White Sheep was examined in an experiment contucted in cooperation with sheep producers in Northern Norway. The mutations were shown to have a positive effect on fatness and muscle mass, but the Norwegian mutation also led to increased lamb mortality.

The results are already in use
The identification of these mutations have been put into practical use for the sheep producers in that The Norwegian Association of Sheep and Goat Farmers (NSG) have excluded rams that carry the mutations from use in AI.

Inger Anne Boman is 39 years old, and comes from Oslo and Bergen. She took her Cand. Agric degree at IHA in 1995.

The trial lecture and the public defence took place Monday June 29 2009 at IHA. Title of the thesis: Mutations in the Myostatin (MSTN) Gene in Norwegian Sheep. Prescribed subject of the trial lecture: Strategies for detecting and utilising mutations affecting muscle mass in sheep.

Boman's main supervisor has been Professor Gunnar Klemetsdal, IHA. Professor Dag Inge Våge, IHA/Cigene has been assistant supervisor.

Updated: 05.07.09
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