The Effects of Myostatin in Red Polls

In the Autumn 2012 Newsletter, an overview was given of the findings of Dr. Pam Wiener and others at the Roslin Institute in Edinburgh as to the effects of the Myostatin variant in South Devons and it was reported that we were hoping to secure funding to allow the Society to work with Dr. Wiener on a study of the effects of the Myostatin variant in Red Polls.

Our application to the Technology Strategy Board for £5,000 was successful and, as a result, an additional 300 samples were tested for the variant by Neogen ( although 20 of these were unacceptable and produced no result.) 60% of the 370 animals tested were non –carriers, as shown in the table.

289 of the animals tested had Signet Records and Dr. Wiener went on to assess the effect of the Myostatin variant on Birth weight, Calving Ease, Fat Depth, Muscle Depth and adjusted 100 to 500 day growth. We wanted to see what the effects were and whether they were or were not similar to the effects found previously in the S. Devons and other Native Breeds. We did not have any data to assess the effect on carcase weight or carcase quality.

Fat Depth and Muscle Depth

As with other Breeds, it was found that the Fat Depth decreased with the number of copies of the variant such that the M2 had about 1.5mm less fat than the M1 and the M1 had about 0.5mm less fat than the M0, the difference between the M2 and the M0 therefore being about 2mm.

Conversely, Muscle Depth increased with the number of copies of the variant such that the M2 had about 3.5 mm more muscle depth than the M1 and the M1 had about 3.5mm more muscle depth than the M0, the difference between the M2 and the M0 therefore being about 7mm.

Birth Weight and Calving Ease.

The average Birth Weight in Red Polls was 40.81 Kgs. The variant had no statistically significant effect on birth weight [although the M2 animals, of which there were 10, were heaviest at birth and at 100 days.]

On Signet, Calving Ease is measured on a score of 1 – 5 where 1 represents no assistance and 5 represents a Caesarean. Overall, the Red Polls had a score of 1.1, meaning there were very few which needed any assistance. There was no evidence that the variant had any effect, adverse or beneficial, on calving ease. The 10 M2 animals all had a score of 1 (no assistance.) There was no evidence that the M1 was heavier at birth or had any decreased calving ease

Growth Rate.

At ages over 100 days the M1 was heavier than either the M2 or the M0 although this was not a statistically significant difference. There was insufficient data to assess the effects on 500 day growth but at 300 days the effect was statistically significant: the M1 animals were 13 Kgs. heavier at 300 days than either the M0 or M2 animals

Comparison with South Devons.

The frequency of the variant is similar in the Red Polls and the S. Devons.

From the previous article it can be seen that, unlike in the Red Polls, the number of copies of the variant had a significant adverse effect in the S. Devons on Birth Weight (the S. Devon M0 averaged 40 Kg, the M1 averaged 41.3 Kg and the M2 averaged 44.9 Kg) and on Calving Ease (the S. Devon M0 scored 1.4, itself worse than the average Red Poll, the M1 scored 1.6 and the M2 scored considerably higher at 2.2, i.e. probably all the M2s needed at least some assistance in calving.) There was also a significant difference between the Red Polls and the S. Devons in the effect of the variant on Growth Rate. In the S. Devons, the M0 and the M1 had similar growth rates but the M2 was some 31 Kg. lighter than the M0 at 252 days (36 weeks.) In the Red polls on the other hand, it was the M0 and M2 which had similar growth rates and the M1 was 13 Kg. heavier at 300 days (43 weeks.)

Interpretation.

When considering the implications of this study it is important to bear in mind that there are obvious limitations because of the relatively small sample size [289 animals for the main analysis whereas the 2009 report on S. Devons had 835 for the calving score, 995 for the birth weight and 2,300 for growth rate.] Nevertheless, it is suggested that this has proved to be a very interesting and worthwhile study providing a number of statistically significant results in various areas. It had always been thought that, although the same Myostatin variant [nt821] was present in different Breeds, the effects of that variant might well differ to a greater or lesser extent between different Breeds. That has been proved to be the case here with very significant differences between the effects on Birth Weight, Calving Ease and Growth Rate in the S. Devons and the Red Polls.

In essence, this study shows that, in the Red Polls at least, the variant acts beneficially to reduce Fat Depth and to increase Muscle Depth but without the adverse effects seen in other Breeds on Birth Weight and Calving Ease, there being no evidence that the variant increases Birth Weight or Calving difficulty in Red Polls. There is the added benefit that the M1 has a higher growth rate than the M0 and the M2 such that the M1 animals were 13 Kg. heavier than the M0 or M2 animals at 300 days. With stores making over £2.00 per Kg. this would give a very worthwhile additional £26.00 per head.

Acknowledgements.

The Society is very grateful for the funding received from the Technology Strategy Board and for the participation and assistance given by Dr.PamWiener of Roslin Institute, Gary Evans of Neogen, Sam Boon of Signet, and all those who provided hair samples from their animals.

If anyone would like a copy of the Report or further information or clarification, please email simon_temple@hotmail.co.uk

Simon Temple