Marbling & Double Muscled Cattle

[MikeC]

Marbling in Double Muscled Steers


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Some breeds of cattle are prone to double muscling. These animals have enlarged muscles, giving them the appearance of being the weight lifters of the cattle world! Double muscling in cattle is the result of a natural mutation of the myostatin gene. Normally this gene stops muscle development, but the timing is off because of the mutation of the gene.
There are a number of breeds that are prone to carrying the gene for double muscling, with two of these being the Piedmontese and the Parthenais. Both breeds have been in existence for a long time with the first official herdbook for the Piedmontese established in Italy in 1897, and for the Parthenais in France in 1893. Both breeds are raised in Alberta. One of the attractions of double-muscled cattle is the leanness of their carcasses. Backfat is generally found to be less in double-muscled cattle than in cattle with normal muscling. Whether or not this affects the amount of marbling fat in the muscle is open to dispute. Some studies have found reduced marbling in double-muscled cattle while others have found no effect of double muscling on carcass marbling.

As part of a large study to determine growth performance and carcass characteristics of cattle with varying degrees of marbling genetics, we included Piedmontese and Parthenais steers. The objectives of this portion of the study were to compare backfat depths and marbling of double-muscled and non double-muscled steers, and to determine if double-muscled steers have altered plasma hormone profiles that might explain how the gene for extra muscle growth is being expressed.

We compared the data from 10 Piedmontese and 8 Parthenais double-muscled steers with data obtained from 38 non double-muscled (control) steers). The control group had 19 Angus, 10 Hereford, 3 Holstein, 3 Hereford x Charolais and 3 Hereford x Simmental calves in it. Calves began the trial at weaning. During the first 2 weeks we put the calves on a roughage diet. We then adapted the calves over a 4-week period to a diet of 80% barley, 15% barley silage and 5% pelleted supplement, which they received until slaughter.

We weighed calves at weaning and every 28 day until slaughter. We also measured ultrasonic backfat depth when we weighed them. We assigned the control group for slaughter when their backfat depths approached 12 mm. However, we assigned the double-muscled steers for slaughter at 500 kg liveweight, instead of at 12 mm of backfat, since they were slow to deposit backfat. We had the calves slaughtered at the Lacombe Research Centre, where blue tag data was collected by certified AAFC beef graders. Carcass marbling was scored on an inverse 10-point scale where a score of '1' is maximum marbling and a score of '10' is zero marbling.

Average live weight at slaughter was slightly higher in double-muscled steers compared to control steers (506 vs. 488 kg). As we expected, double-muscled steers had much less backfat than control steers (5.1 vs. 12.1 mm) at slaughter. Despite this, carcass marbling was similar for both the double-muscled and control steers (8.6 vs. 8.6 marbling score), supporting the view that while double muscling results in less external carcass fat, it does not adversely affect marbling. This is important since marbling is believed to have a role in determining the palatability of beef.

We collected blood samples from the steers three times during this study for the measurement of several hormones known to be involved in the partitioning of energy into either muscle or fat. Plasma insulin concentrations were similar in the double- muscled and control steers (1.2 vs. 1.3 ng/mL). The concentration of plasma triiodothyronine, a thyroid hormone, was slightly lower in double-muscled compared to control steers (1.9 vs. 2.1 ng/mL). Plasma thyroxine, another thyroid hormone, was also lower in double-muscled compared to control steers (7.3 vs. 9.3 µg/dL). We also found that plasma cortisol, an adrenal hormone was substantially higher in the double-muscled steers (12.3 vs.6.9 µg/dL).

Our study indicates that Piedmontese and Parthenais steers put on much less backfat without reducing the amount of muscle marbling. These breeds have adrenal and thyroid hormone concentrations that are different from those of normally muscled cattle, an indication that the mutated myostatin gene may be expressing itself through these hormonal systems to alter muscular development and fat deposition in these cattle.

 

[waihou]

Interesting report. Did you gene test the animals for the marbling genes as well?

 

[Jeanne - Simme Valley]

The problem with double muscled steers is selling them.
USDA graders "no rolls" them, making them less valuable in the normal market.

 

[MikeC]

The problem with double muscled steers is selling them.
USDA graders "no rolls" them, making them less valuable in the normal market.

Not true if graded in the "Grading" line of harvested animals.

Grading is an optional program. If a packer pays for a grading inspector, he will get just that............. "Grading".

If they marble as well as others, they get the grade

"No Roll" is the designation given to carcasses that are not graded.

 

[Jeanne - Simme Valley]

I'm not understanding your remarks.

USDA does not accept double muscling in their grading system.
Double muscled cattle are "no rolled" or rejected by the USDA inspectors under the current grading system. For custom processing this is no problem but for commercial cattle they are.

 

[3waycross]

I'm not understanding your remarks.

USDA does not accept double muscling in their grading system.
Double muscled cattle are "no rolled" or rejected by the USDA inspectors under the current grading system. For custom processing this is no problem but for commercial cattle they are.

Where does your info concerning the USDA come from. I'm not saying it's not true just would like to see it in print.

My understanding of carcass grading is the same as MikeC. If the intermuscular fat( that which is within the muscle) is there it grades, if it's not there it does not "ROLL".

I also am not sure Double Muscling is an appropriate description of these cattle. To me that would denote 2 of each muscle which I'm pretty sure is not the case. I wonder if Super Muscling would not be a better description.

 

[Jeanne - Simme Valley]

I tried to locate a site with this info but unable to.
I'm sure if a Piedmontese breeder or Bel Blue breeder was on here they would confirm what I said.
It has been this way for many, many years.
Double muscled carcasses are REJECTED - "no rolls".
I emailed Cornell to see if they could point me in right direction to get it "in writing".

 

[MikeC]

I'm not understanding your remarks.

USDA does not accept double muscling in their grading system.
Double muscled cattle are "no rolled" or rejected by the USDA inspectors under the current grading system. For custom processing this is no problem but for commercial cattle they are.

Jeanne, You are confusing the grading of "Feeder" cattle and "Slaughter" cattle.

Double muscled "Feeder" cattle (live and on the hoof) used to summarily be called "Inferior" because of the unknown finishing qualities. David Gonsoulin, the USDA grader in my area does not use the term "double muscled" when grading feeder animals through our local markets, nor does he grade them "Inferior" any more, due to demand for these by the buyers.

The "No Roll" stamp is used by packer employees (large or small........commercial or custom) to identify cattle that have not been given a USDA Quality or Yield Grade stamp.

USDA Grading is a voluntary act by a packer whether he be, again, large or small......commercial or custom.

Double Muscling does not automatically disqualify (or "No Roll") an animal to be graded by a USDA Grader on the "Slaughter" line. If a double muscled carcass passes by a USDA Grader, the animal is graded according to the rules and regulations he adheres to, which has no designation for double muscled animals.

 

[ALACOWMAN]

I'm not understanding your remarks.

USDA does not accept double muscling in their grading system.
Double muscled cattle are "no rolled" or rejected by the USDA inspectors under the current grading system. For custom processing this is no problem but for commercial cattle they are.

Where does your info concerning the USDA come from. I'm not saying it's not true just would like to see it in print.

My understanding of carcass grading is the same as MikeC. If the intermuscular fat( that which is within the muscle) is there it grades, if it's not there it does not "ROLL".

I also am not sure Double Muscling is an appropriate description of these cattle. To me that would denote 2 of each muscle which I'm pretty sure is not the case. I wonder if Super Muscling would not be a better description.

the term double muscle . doe's not mean two of each its refer to twice the same muscle size. like working out after awhile you'r biceps will be twice as big . ive read were no roll if it graded would be select

 

[Frankie]

Yes, "interesting" article.

"Carcass marbling was scored on an inverse 10-point scale where a score of '1' is maximum marbling and a score of '10' is zero marbling."

This little study doesn't show that double muscled animals marble; it just shows that not all normally muscled animals marble.

 

[3waycross]

I'm not understanding your remarks.

USDA does not accept double muscling in their grading system.
Double muscled cattle are "no rolled" or rejected by the USDA inspectors under the current grading system. For custom processing this is no problem but for commercial cattle they are.

Where does your info concerning the USDA come from. I'm not saying it's not true just would like to see it in print.

My understanding of carcass grading is the same as MikeC. If the intermuscular fat( that which is within the muscle) is there it grades, if it's not there it does not "ROLL".

I also am not sure Double Muscling is an appropriate description of these cattle. To me that would denote 2 of each muscle which I'm pretty sure is not the case. I wonder if Super Muscling would not be a better description.

the term double muscle . doe's not mean two of each its refer to twice the same muscle size. like working out after awhile you'r biceps will be twice as big . ive read were no roll if it graded would be select

I'm pretty sure that is what I was trying to say. That's why doubl muscling is a misnomer.

 

[MikeC]

Belgium is not exactly known for wide-open spaces and sprawling ranchlands. So farmers there had to learn to do more with less. Over the last 30 years, they have bred a strain of cattle--the mighty Belgian Blue--that gives 20% more meat per animal on roughly the same food intake as ordinary animals. indeed, the cattle develop such bulging muscles that in extreme cases they have trouble walking and the calves are so big they have to be delivered by cesarean section. Now, three research groups have independently uncovered the genetic cause of this "double-muscling" trait, a discovery that may lead to meatier strains, not just of cattle, but of other agriculturally important animals as well.

In the September issue of Nature Genetics, a pan-European team led by Michel Georges of the University of Liege in Belgium reports that double muscling is caused by a mutation in the bovine version of a recently discovered gene that makes a protein called myostatin. The other two groups, one co-led by Tim Smith of the U.S. Department of Agriculture (USDA) lab in Clay Center, Nebraska, and the other by Sejin Lee of Johns Hopkins University, also found that the myostatin gene is mutated in Belgian Blues and have linked mutations in the gene to double muscling in a second breed of cattle, the Piedmontese, as well. [The Smith team's results are in the September issue of Genome Research, and Lee's are in press in the Proceedings of the National Academy of Sciences (PNAS).]

Discovered just 4 months ago in mice by Lee and his graduate student Alexandra McPherron, myostatin normally serves to limit skeletal muscle growth. Apparently, the mutations block its activity and the animal's muscles grow larger-but without harming meat quality. While some other cattle breeds are also abnormally well muscled, presumably because of as-yet-undiscovered mutations, the muscle fibers in those animals are thicker than normal, toughening the meat. In contrast, the muscles of animals with myostatin mutations have larger numbers of normal-size fibers. Indeed, says Smith, meat from the Belgian Blue is "so tender even round steaks fall apart on the grill." Nevertheless, the meat is lower in fat than that from ordinary breeds.

Given those effects of myostatin mutations, it's not surprising the gene is attracting attention from agricultural scientists. "This is the first gene identified in cattle that controls a combination of muscle size and tenderness," says molecular geneticist Mike Bishop of ABS Global, a biotech firm in Madison, Wisconsin. He notes that beef palatability, as well as yield, might be improved by introducing myostatin gene mutations into cattle or by finding drugs that turn down the gene's activity. Such strategies might also lead to meatier pigs, chickens, and turkeys, as the Lee team found that the myostatin gene has relatives in these and other farm animals.

The meandering cow path to this discovery started in Belgium in the 1950s, Georges says. Cow breeders there, who were under economic pressure from cheaper imports and high production costs, wanted to increase their yields and began to select for the double-muscling trait, which had been reported as early as 1807. Before long, nearly every beef cow in Belgium was a purebred double-muscled animal.

Beginning in the late 1980s, Georges's team spearheaded an effort to isolate the cause of double muscling. "We were so convinced that any gene . . . that had such a spectacular effect on muscular development had to be a very important gene for animal agriculture," he recalls. By 1995, Georges and his colleagues mapped the gene to a region of cow chromosome 2, but then the effort stalled because they still had a lot of DNA to search through.

A break came in May of this year, however, when Lee and McPherron described the myostatin gene and showed that when it is missing in mice, the animals grow into muscle-bound hulks two to three times the size of normal animals. That publication launched a race to find the equivalent bovine gene, as the implications for cattle--if such a gene existed--were obvious.

The group led by Georges--which included researchers from Germany, Spain, and France--used a neat trick involving a third species, humans. The full human gene has not yet been published-it will be in Lee's PNAS paper--but the researchers found that a database of human ESTs (expressed sequence tags) contained sequences similar to those of the mouse gene. Although ESTs are short--100 or 200 bases long--Georges and his colleagues found enough overlapping ones to piece together most of the human gene. After cloning it and mapping its chromosomal location, they played a hunch and compared the site of the human gene with a map of bovine chromosome 2.

The effort paid off. "We then realized," says Georges, "that the position of the myostatin gene on the human map coincided exactly with the position of the double-muscling gene on our bovine genome map." From there, they cloned and sequenced the bovine myostatin genes from both double-muscled and normal cattle.

The sequences revealed that the gene from the double-muscled animals carries an inactivating mutation--an 11-base pair deletion--that results in "virtually complete truncation" of the active region of the protein, Georges says. That lifts the normal repression of muscle growth by myostatin and opens the way for extra brawn.

The Lee team used a similar approach to come up with the Belgian Blue gene. The researchers then guessed that double-muscled Piedmontese cattle would also have a mutated myostatin gene, and when they cloned it, that's what they found. Smith, working with John Baff's team at AgResearch in Ruakura, New Zealand, took a somewhat different tack, using the mouse gene to first find the gene in normal bovine DNA and then in Belgian Blues and Piedmontese, where they, too, found mutations. Similar mutations could also add bulk to other farm animals, for the Lee team has found the gene in all nine species they examined, including mammals, such as the pig, and birds, including chickens and turkeys.

T'he myostatin work may help to identify other genes that influence muscle growth. Piedmontese cattle don't develop the extreme double muscling of Belgian Blues, even though the mutation that the Smith and Lee teams found in their gene is probably sufficient to inactivate the protein. That suggests that the lesser amount of double muscling in Piedmontese cattle is due to other genes that make up for the loss of myostatin.

Despite the interest in using the myostatin gene to improve beef production, researchers warn that it may be a difficult task. One possibility is to use either conventional breeding or genetic engineering to introduce the Belgian Blue mutation into other breeds. So far, however, U.S. breeders have only rarely attempted to do this, even by conventional breeding. This is partly for practical reasons. The need to deliver calves by cesarean section is a serious handicap in the United States, where cattle herds are larger and roam over much wider areas than they do in Belgium.

That problem might be overcome, if researchers can find a less extreme myostatin mutation or identify another gene with a less drastic influence on muscle mass, allowing the calves to be delivered naturally. But there are also worries about whether the public would accept genetically engineered beef. The cattle industry has until now shied away from funding research into transgenic animals for human consumption. "They perceive it as too sensitive and risky an area," Smith says.

Another possibility would be to find some drug that can turn down myostatin activity in animals with the normal gene. And then there may be other genes that can be manipulated. Researchers in at least four countries are mapping the cattle genome, and reproductive physiologist Vernon Pursel of the USDA research labs in Beltsville, Maryland, says "we are getting to the point where there will be a number of genes" like myostatin identified in the near future. Extra helpings of tasty meat at essentially no cost could prove hard to resist.

--Steven Dickman

 

[Frankie]

I tried to locate a site with this info but unable to.
I'm sure if a Piedmontese breeder or Bel Blue breeder was on here they would confirm what I said.
It has been this way for many, many years.
Double muscled carcasses are REJECTED - "no rolls".
I emailed Cornell to see if they could point me in right direction to get it "in writing".

Are you talking about full bloods or cross cattle? Because the cross will grade as good as anything and better than most. All you have to do is look at some studies done.

Crossed with what? Quality grade or Yield grade? Let's see some of those studies.

 

[Jeanne - Simme Valley]

I am not confusing feeders with carcass animals. And I am talking about all double muscled cattle. They don't have to be purebred of anything. Charolais used to have dm in their breed & they chose to breed it out of their gene pool.
As to date, it is an undesireable trait.
As Mikes' article says, "the cattle develop such bulging muscles that in extreme cases they have trouble walking and the calves are so big they have to be delivered by cesarean section."
I watched a Bel Blue bull calf get loaded onto a horse-trailer. It was about 10" off the ground and the people had to pick up each foot & put it up on the floor of the trailer, becasue the animal was incapable of stepping up that high.
Why in the world would anyone here want to create cattle that cannot propagate without man's interverence (cesarean's & posibly only AI)
I still stand on the fact that DM cattle are not ALLOWED to be officially graded. I'm working on getting "facts". I'll report if I find I'm wrong - but I don't think so!

 

[MikeC]

Apparently, there are varying degrees of "Double Muscling" in cattle due to the homozygosity and heterozygosity of the alleles that inhibit myostatin production.

Simply, a DM animal does not have to be so muscle bound that he/she cannot walk or calve normally.

Just because they are called "Double Muscled", does not mean that they have twice the muscles, nor does it mean they have muscles that are twice the size of normal muscled animals.

It only means that the individual muscle cells are larger than normal from increased oxygen intake.

This could be very positive for the cattle/beef industry in the future.

By the way, was reading one study that included Angus cattle that were double muscled. :shock:

One of the reasons I have been so interested in these projects is that I fed a DM'ed X-bred Limousin back a few years ago and found the meat to be superior to any I have ever eaten by a large margin. It was tender as all get-out, tasted great, (even though it was a bright pink instead of a dark red) and hung a 70% carcass that gained really fast and efficiently.

 

[MikeC]

Care to list the other breed.

I don't have a clue.

 

[Jeanne - Simme Valley]

I just got a report from a packing plant grader thru Cornell.

DM cattle CAN be graded. There is no defference in the grading.

"I have never no rolled a double muscled animal because it was double muscled. They grade what ever quality they are. The issue that may be causing some confusion is the majority that I see are lower quality to start with, that is usually low select. I have had them choice from time to time but usually they are low select or standard. I can't think of any that went prime, but that doesn't mean they can't if the quality's there. They also have a tendency to yield in the 1 and 2 range more often other types of cattle and as you know the fat is stored in the lean third, after the KPH and external governing is satisfied. "

So, I was wrong, sorry. Maybe I'll remember this the next time - but maybe not - like Dun says, between now & then, I would have slept

 

[CKC1586]

I just got a report from a packing plant grader thru Cornell.

DM cattle CAN be graded. There is no defference in the grading.

"I have never no rolled a double muscled animal because it was double muscled. They grade what ever quality they are. The issue that may be causing some confusion is the majority that I see are lower quality to start with, that is usually low select. I have had them choice from time to time but usually they are low select or standard. I can't think of any that went prime, but that doesn't mean they can't if the quality's there. They also have a tendency to yield in the 1 and 2 range more often other types of cattle and as you know the fat is stored in the lean third, after the KPH and external governing is satisfied. "


So, I was wrong, sorry. Maybe I'll remember this the next time - but maybe not - like Dun says, between now & then, I would have slept

Thanks Jeanne for clearing that up.
As I understand it, the issue is with marbling. The muscle enhanced cattle have lean and tender beef without being all marbled up. The Piedmontese have a natural occurring double copy myostatin gene, but it is not manifested in the calves until they are about a month to six weeks old so they don't have the issues that some of the other "DM" breeds are known for. When crossed they pass 1 copy of this tenderness gene and the result is improved carcass yield and very tasty tender beef. (Less fat, less waste).

 

[MikeC]

I just got a report from a packing plant grader thru Cornell.

DM cattle CAN be graded. There is no defference in the grading.

"I have never no rolled a double muscled animal because it was double muscled. They grade what ever quality they are. The issue that may be causing some confusion is the majority that I see are lower quality to start with, that is usually low select. I have had them choice from time to time but usually they are low select or standard. I can't think of any that went prime, but that doesn't mean they can't if the quality's there. They also have a tendency to yield in the 1 and 2 range more often other types of cattle and as you know the fat is stored in the lean third, after the KPH and external governing is satisfied. "

So, I was wrong, sorry. Maybe I'll remember this the next time - but maybe not - like Dun says, between now & then, I would have slept

Thanks for your honesty Jeanne. I knew for a fact that DM carcasses were graded but didn't press the issue out of respect for you personally.

There are other issues with DM cattle that make Cattlemen reluctant to embrace the concept at this time, but the infusion of the alleles (probably in a heterzygotic state) will help cure some of the woes we have with backfat in the future.

Maybe we can rid ourselves of all the "Funnel Butted" cattle in the markets and pride ourselves in providing more tender, more efficient, and more consistent beef to the consumer........

Thanks again.

 

[mitch2]

Not to get off on a tangent here...

My husband recently met a fellow who helps to sell butchering meat for his grandfather(?) or uncle (?) sorry can't remember. This guy sells a lot of meat to employees at my husbands place of employment. I think this fall he said he sold like 22 animals for butchering, just to employees he works with.

Anyway, these animals are Belgium Blue X Angus... I am not sure on the %'s, but I keep nagging hubby that I would like to get a look at these critters. People say it is some of the best meat they've had, buy from him year in and year out. Hanging carcass weights are 1100# plus :shock: :shock: :shock:

My thought was he would probably get docked on the grid (or auction) due to the size of the carcass... am I wrong here? If I am correct, then he almost has to sell privately.

If I ever can get over to see them and he lets me take some pics, I will definitely post them here.

Michele