Some decades ago when Murray Greys were winning all the carcase competitions I recall a comment from an industry judge. He paid a compliment to the early breeders of Murray Greys saying that they had established cattle with the best and most even coverage of finish or fat cover. Talking with various people since that time, the importance of getting an even coverage on ribs and rump has been emphasised.
When we scan our cattle I have been interested to see how well the fat depth compares between rib and rump; suffice to say the measurements are usually the same. Likewise the EBV values for Rib EBV and Rump EBV are usually always equal or very close.
Since we have been dabbling with Angus, comparing them with Murray Greys, I have looked at a few Angus Breedplan figures and immediately noticed that the rib and rump EBV figures often varied quite a bit in the same animal. Sometimes the fat was thicker over the rib and sometimes over the rump. This information has sat in the back of my mind for over a year and I decided to look at the issue in more depth over this wet weekend.
So I pulled the results from the best 2,000 bulls in Angus and Murray Grey breeds based on their financial indices and plotted the rib and rump fat EBVs. In both breeds there is a fairly broad distribution in the amount of fat within the groups examined. There is a strong correlation between the rib and rump EBVs in the same animal, however the correlation is significantly stronger in MGs than Angus (99% vs 90%). The average gap between the two EBV figures in an individual animal is greater in Angus (0.44) than in MG (0.26). The situation is demonstrated in the following figures.
Clearly Murray Greys have a more even fat coverage than Angus; the result confirming what the early breeders have achieved by their selection. We should be able to emphasise this advantage of our cattle in our marketing.