Knowledge Base: Myostatin Article Autumn 2012

Myostatin is a gene which regulates the formation of muscle. Various mutations of this gene have been found in cattle. The Red Poll, along with the South Devons, Aberdeen Angus and Belgian Blue, have the nt821 mutation. The most obvious effect of the mutation is to allow the animal to produce more muscle. The Belgian Blue is an extreme example. In the Spring 2012 Newsletter it was reported that the Society had started a programme of testing Bulls for the Myostatin nt821 mutation. That programme has continued and all young Bulls are now tested when they are inspected. We have also tested some of the AI Bulls and some females. We have results for 90 animals (75 Males and 15 Females) which show that 50% of the sample [38 males and 7 females] do not carry any copy of the mutation [we refer to these as "M0"]; 43% [34 males and 5 females] carry one copy of the mutation ["M1"] and 7% [3 males and 3 females] carry 2 copies of the mutation ["M2"] which can properly be called "double muscled".

Whilst the testing of young bulls will continue, we are hoping to secure funding to allow us to test a further 300 animals so that we can obtain a much more accurate estimate as to the prevalence of the nt821 mutation within the National Red Poll Herd. But we also want to find out more details of how the mutation affects the performance of Red Polls.

A number of studies have been undertaken previously, by the Roslin Institute and others, into the effects of the nt821 mutation in various breeds of cattle. The results vary from breed to breed. Not surprisingly, the Belgian Blue shows the most extreme results.

An idea of how the Red Poll might be affected can be seen from the results of a recent study into South Devons [Wiener et al. Meat Sciences 83 (2009) 127-134]. This showed that:

1. The effect of the mutation was to increase birth weight and calving difficulty. The birth weights of the M0s averaged 40 Kg, those for the M1s averaged 41.3 Kg and those for the M2s averaged 44.9 Kg. On a calving score of 1-5, the M0s scored 1.4, the M1s scored 1.6 and the M2s scored 2.2. Whether the cow was M0, M1 or M2 had no significant effect on calving ease.
2. Growth rates for the M0 and the M1 were very similar but the M2 had a slower growth rate: the M2 grew 0.143 Kg/day slower than the M0.
3. The mutation had a considerable effect on the carcase quality, increasing carcase weight and muscle score and decreasing fat scores. The carcases of M2 animals were 14 Kg heavier than M1 animals which in turn were also 14 Kg heavier than the M0. [so, although they had a slower growth rate than the M0, the M2 had a heavier carcase than the M0.] On a muscle score of 1-15, the M0s scored 6.6, the M1s scored 7.6 and the M2s scored 10.1. On a fat classification of 1-15, the M0s scored 6.4, the M1s scored 5.2 and the M2s scored 4.4.    

It is hoped that we will be able to join with Dr. Pam Wiener from the Roslin Institute to carry out a similar study into the effects of the nt821 mutation in Red Polls when we will see whether the effects are different to those for the South Devons and the other breeds. If our funding application is successful we should have the results from such a study by Spring 2013.