my apologies, the poster on another board is Dr. Bill Switzer, not Swift
here's a few cut and pastes from another site
one comment i find particularly interesting is "This is why the marbling readings on a Monday, of Friday killed animals is usually a little higher by visual appraisal. Some of the invisible fat has coalesced into visible specks with the extra time in refrigeration."
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Along this same line I would like to mention one basic difference between "visual" and "machine" grading of carcasses.
The traditional and still official carcass grade determination by Federal Inspectors is based on visual inspection of the freshly cut surface for visible flecks, specks and streaks of marbling. In modern processing plants the time available for this inspection may be under 10 seconds.
Machine (ultra sound) determination of the amount of marbling present is determined by the intensity of ultra sound energy reflected back by the components of the muscle. This level of reflection is compared to charted fat solvent extract values of research measured and visually appraised muscle. The fat content of the muscle that is in clumps too small to be visible to the human eye are in the extract as well as those that are visible.
This is why the marbling readings on a Monday, of Friday killed animals is usually a little higher by visual appraisal. Some of the invisible fat has coalesced into visible specks with the extra time in refrigeration.
The recent realization that there is a rare, fine particle, uniformly distributed in the muscle, type of marbling in Angus suggests that when extraction/ultra sound reading correlations are available they could explain some amount of the often cited modest failure of correlation between visual and machine read IMF values. When the yard stick for accuracy has been the amount of extractable fat, never bet against the ultra sound reading!
This possibility is one of the reasons I'm quite interested in my "Smokey" marbling line. It is a daunting task for a small breeder to tackle but also exciting.
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and another
There are now 10 marbling and tenderness DNA test readings. More are probably in development. A lot of producers are watching and several are applying the tests. There have been a very few 10 star bulls identified to date. It is probable that this flurry of new DNA test for these traits is not over yet and producers are still uncertain how many are important.
It is also probable that these two traits are influenced by many factors so the total effect may involve a fairly large number of different genetic factors similar to the genetic basis of milk production.
I am very interested in a novel kind of marbling I call "smokey marbling". It is very fine particles of IMF uniformly distributed. I am hopeful that it will result in significantly enhanced flavor in beef. If by some miracle this should work out there would be the added factor of flavor as well as marbling and tenderness.
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It is a generalization that each breakthrough in knowledge leads to the next breakthrough in an ever shorter time. The better understanding of the function of various cellular components has led to an almost startling series of findings demonstrating that fat droplets are not simply passive little sacs of potentially metabolizable energy stored away in a fat cell.
The amount and kind of fat and where it is stored are big ticket items in the value of a beef carcass or in a wintering beef cow so understanding some of this newer information about how fats function in cells should be of interest.
A very good review article in the March 3, 2006 issue of Science summarizes many of these new understandings.
A few of the highlights that seem most interesting to follow because of possible relationship to ongoing developments in the beef industry are the following.
The rich energy store the fat droplet represents is safeguarded by a surface layer of the protein perilipin. When this protein is absent experimental mice eat more food than normal mice but burn up two thirds more fat than a normal mouse did. "Their metabolic rate is as if they are exercising all the time". This is very recent research in mice. Did you ever know a lean human that you could actually feel the body heat radiate from when they were standing still close to you? I hope the feed efficiency researchers check this out.
Lipid droplets are now known to be involved in the synthesis of cholesterol.
A lipid droplet has many different kinds of proteins attached to its surface. Some of these are now believed to be formed as the fat droplet is formed. One of these surface attached materials called leukotriene is readily transferred to nearby proteins. When this substance is transferred to the appropriate nearby protein the formation of prostoglandins results. Certainly seems to me a good reason to have cows on a gaining cycle for breeding season.
Lipid droplets in the cytoplasm are now known to assist in moving membrane structures around within the cytoplasm. Reminds me of the "greasers" applying fat to the timbers that were used to skid the huge stone blocks used to build some ancient structures.
One item that especially interested me was the observation that as the lipid droplet became smaller and smaller the greater the ratio of perilipin. One more thing to ponder about "smokey marbling" animals. Would their marbling be more stable?
I think one statement in the article is an excellent "bottom line message".
"Lipid droplets are much more complex than people imagined".
Hope you find this interesting.
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I have several nice quality daughters in the herd now that I will be mating him to this Spring. I think that will give me some good foundation cows.
I have heard a rumor that there is a bull on the west coast that is siring some smokey calves. Only they call it "cotton" marbling. That bull is related to my smokey bull.
The SynGen Corona bull is also in the same family as my smokey bull. The owner of Corona generously shared the image of the US scan of Corona with me. Corona has very nice marbling but it does not appear to be smokey.
The dam of the smokey bull came up open last Fall at 11 years of age. She had produced 9 calves. She went to market. Smokey has proven to handle Fescue grass well in the herd of my partner on the bull so I plan to use him this Spring in the herd we moved to fescue pasture about a year and a half ago.
About all the update I have on the smokey marbling bull for you Alex. Thanks for your interest.
