Quicker carcass improvements

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Apr 10, 2004
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Traditional animal breeding theory indicates that within a breed, the most effective genetic selection is made through progeny testing. Progeny testing would not be a practical method to improve tenderness due to the time and expense required to develop and evaluate progeny. The rate of genetic improvement in a given trait is a function of the heritability of the trait, the generation interval, and the selection differential. If we make the following assumptions: use 13 sires, hold inbreeding to less than 1%, 100 cow herd size, heritability estimates of 0.30 for shear force and 0.42 for marbling, the genetic correlation 0.25 between shear force and marbling (Koch et al., 1982, and the references therein), standard deviation of 1.0 kg for shear force, then it would take 12.0 years or 40.7 years to improve shear force by 1.0 kg by selection for shear force or for marbling, respectively. If we increase the size of the cow herd to 500, the above estimates would be 6.8 and 23.1 years, respectively. Obviously, a significant change in the above parameters will affect these estimates. There is evidence to suggest that significant improvement in shear force measurement can be made (Koohmaraie et al., 1995c; Wheeler et al., 1994b; Wheeler et al., 1995b) to improve its accuracy, which may change the heritability estimate for shear force and, thus, the time required to make improvement through selection. (Quoted from MARC )

I think that using ultrasound would speed up the progress. Any thoughts?

You sure dug up a good one! My first thought would be that this would appear to be more of biochemical assay related approach rather than a phenotypic (Physical) one which would be measurable via sono with a couple of outliers. It would seem to me that a large amount of research is currently ongoing on the calpain/calpastatin system, which as you already know is responsible for the degradation of muscle tissue that is no longer viable. As muscle cells get old or die they are degraded by the enzyme u-Calpain, which is readily available in the blood stream. Under normal conditions u-Calpain is inhibited from acting by calpastatin, which is also present in the blood stream, it keeps the scales balanced so to speak. Once the animal dies there is a cascade of dying cells which release their intracellular contents, proteins, Ca2+, etc, into the blood stream which binds up the calpastatin thus allowing the u-Calpain to go to work on the myofibrils of the muscle tissue and initiate destruction/digestion accounting for the tenderness. From what I have read thus far there appears to be somewhat of an increase in the titer of u-Calpain in double muscled cattle. At this juncture it is theorized that Calpastatin activity at 24-h postmortem accounts for a greater proportion of the variation in beef tenderness (approximately 40%) than any other single factor. It seems unlikely to me that sono could measure the level of enzymatic muscular digestion that would occur after an animal expires but then again I learn something everyday.

Angus cattle (Hold on boys I am not picking on anyone’s breed.) are known to be Double-muscling cattle, a recessive trait in cattle which results in extreme muscularity and higher Carcass Yield. From a physical view point one could gain insight on these cattle via sono; However, Western Blot testing for u-Calpain levels might be more indicative but then again the titers of u-Calpain might be identical in single muscle cattle vs. double-muscled cattle. Another thought would be that the double muscle cattle having a higher density loose body heat at a lower rate at the time of death thus maintaining the optimal temperature at which this enzyme (u-Calpain) functions and allowing for more degradation. As I said above, there seems to be a flurry of research on this topic right now so the jury is still out but one would have to wonder if you could tip the scales of equilibrium in this chemical equation with mineral supplementation of higher levels of Calcium prior to slaughter.

Guess I have more questions than answers, but terrific post ! I have been scratching my head all morning.

Table 1. USDA Carcass Yield and Quality Grade Factors for Normal-Muscled and Double-Muscled Cattle
Muscling Type
Traits Normal-Muscled Double-Muscled P-valuea
Yield Components
Slaughter weight, lbs. 1044.0 1100.0 NS
Hot carcass weight, lbs. 617.1 723.1 **
Dressing percentage, % 59.1 65.7 **
Fat over the ribeye, in. .41 .11 **
Ribeye area, in2 11.1 17.1 **
Ribeye area/hundred weight of hot carcass, in2 1.80 2.36 **
Kidney, pelvic and heart fat, % 2.1 1.5 **
USDA yield grade 2.8 0.4 **
Quality Components
Overall maturityb A32 A36 NS
Marbling score Sm48 Tr76 **
USDA quality grade Ch- St+ **
aNS, Means not different (p>.10); **Means differ, (p<.01).bThe average of lean and bone maturities.
Tman":3649yq16 said:
Angus cattle (Hold on boys I am not picking on anyone’s breed.) are known to be Double-muscling cattle, a recessive trait in cattle which results in extreme muscularity and higher Carcass Yield.

Angus are not known to be double-muscled & do not have higher carcass yield. Angus are known for their ability to marble and have higher carcass grades.
Anonymous":36q9edg0 said:
Angus are not known to be double-muscled & do not have higher carcass yield. Angus are known for their ability to marble and have higher carcass grades.

To clarify, when I said carcass grades, I meant higher quality grades, or more likely to grade prime.

Thank you for the clarification and yet another learning opportunity. As I poured through resrearch articles I misread some of the reports. As you noted Angus are normal muscle not typically double muscled; however do carry the gene for this recessive trait which leads to the hypertrophy the muscles. Still one would have to wonder if manipulation of the calpain/calpastatin system would provide the same results with fewer calving problems in normal muscled cattle.

Thank you again for the clarification and the learning opportunity. Hats off! :cboy:
I enjoyed your post however for clairification on my part in my original post the time factor I was refering to was the genetic selection and improvement as it is related to marbling and thus the correlating shearforce value. However as you said taken in context of the whole artical the study showed that calpain/microfibril degradation effect had a higher correlation to tenderness. Obvious to me that you know way more about it than I do. Would you happen to know of any studies that relate to the structural aspect of the muscle tissue like the size of the muscle strands or connective tissue, and tenderness. I'm quite sure I am asking questions that are stupid. Please set me strait or pm me with info.
Thanks Ollie
This seems like it could be a much better discussion than many that we have in the past.

I would like to see Tman's info posted here.
la4angus":2kgomcr8 said:
This seems like it could be a much better discussion than many that we have in the past.

I would like to see Tman's info posted here.

I would guess that only about 2% of the posters on this board can understand & follow this discussion.
Anonymous":2v3mnzdi said:
la4angus":2v3mnzdi said:
This seems like it could be a much better discussion than many that we have in the past.

I would like to see Tman's info posted here.

I would guess that only about 2% of the posters on this board can understand & follow this discussion.

All the more reason to post it. We might can all learn something from it.
Ones that don't want to read it or try to understand it can just skip over it.
anybody serious about beef cattle should print this thread and at least ask questions.

I appreciate your support, if only 2% understands today then tomorrow it will be 4%, then the next day 16%, etc. I do not have many answers but agree that communication is the way to advance our knowledge. I appreciate all that I have learned here on the boards and hope that I can contribute in some manner. Besides, I have aksed many silly questions and you guys have answered them politley even though I may have asked them many times.

Enjoying the chat hope I don't stray to far.

To restrict the conversation strictly to timelines I would still have to say no that ultrasound would not improve the ability to speed up the process in determining a decrease in Warner Bratzler shear force measurements however it could affect the timeline on deciding which progeny are exhibiting an advancement in marbling.

If I am thinking correctly it would seem that we are presented with two totally unrelated variables, marbling and Warner Bratzler shear force measurements. Assuming that the original strength of muscle tissue is a component of and created by the Primary Structure (Atoms), the secondary structure (Molecules), the tertiary structure (The way molecules interact with themselves and others by folding towards positive or negative charged particles within that molecule) and quaternary structure (Multiple molecules forming complex tissues) it would seem reasonable that marbling is an extracellualr factor rather than an intracellular factor. In other words marbling is fat cells interspersed between the muscle cells and not actually part of the muscle so the muscle integrity is not compromised. One could reasonably assume that this dispersement would cause a weakness in the integrity of the overall strength of the muscle which would lead to decreased Warner Bratzler shear force measurement, however from what I have read this is not true. I believe the reason for this is that the test does not consider a given mass of muscle but rather the entire muscle that is tested (Could be wrong) Consider the following article:

Use of Expected Progeny Differences for Marbling in Beef: II. Carcass and Palatability Traits
B. L. Gwartney, C. R. Calkins, R. J. Rasby, R. A. Stock, B. A. Vieselmeyer, and J. A. Gosey
Department of Animal Science, University of Nebraska, Lincoln 68583-0908
ABSTRACT A 2-yr study was conducted to determine the effect of EPD for marbling on marbling score, palatability traits, and carcass fatness in beef. Steer (n = 122) and heifer (n = 123) carcasses were obtained by mating Angus bulls having a high (>.4) or low (<-.16) EPD for marbling to MARC II cows (¼ Angus, ¼ Hereford, ¼ Simmental, and ¼ Gelbvieh). Carcass traits, composition of primals, quarters, and sides, palatability, and shear force data were obtained and adjusted to the mean number of days on feed, equal marbling score (Small50), fat thickness (1.0 cm), and carcass weight (318 kg) end points. Steer carcasses from the high marbling EPD group, adjusted to the mean number of days on feed, had significantly more marbling (P < .01) and less subcutaneous fat in the side and the hindquarter (P < .10) than their low marbling EPD counterparts. Adjusting steers to Small50 marbling produced smaller longissimus muscle area (by 5 cm2), less fat thickness (1.15 vs 1.28 cm), and lighter side weights (306 vs 333 kg) for high marbling vs low marbling EPD groups, indicating a faster rate of marbling deposition. Similar relationships of a greater magnitude were found for heifers, perhaps because the heifers were older than the steers at slaughter. No differences in taste panel ratings or shear force values were noted among steer carcasses. Heifer carcasses from the high marbling EPD group had better (P < .05) ratings for juiciness, muscle fiber tenderness, and overall tenderness than the low marbling EPD group heifers. These results indicate that it is possible, using existing genetic resources, to maintain marbling score and decrease fat in other depots of the carcass without compromising palatability.

So marbling may or may/not be related to Warner Bratzler shear force measurements but obviously could be picked up by sono which could speed up the breeding process.

Originally I postulated a correlation between the reversal and breakdown of the hierarchy of at least quaternary and tertiary structure through the degradation of tissues via enzymes. Simply put it was created by a chemical reaction and thus it can be reversed with a chemical reaction.

Once again I would speculate that it has more to do with a Primary structure composition (Individual molecules making up compounds) as opposed to a Quaternary composition (Groups of Molecules forming tissues/organelles). Consider this, collagen is a compound that gives connective tissues, including skin and muscle additional strength, and the blue Belgian, a double muscling breed (Thank you guest for your clarification on Double muscled cattle breeds) is known to have a deficiency in this molecular compound as well as a favorable Warner Bratzler shear force measurement. So one could perform muscle biopsies on progeny early on and perform Western blot Assays (Testing looking for specific molecules) it seems reasonable that the process could be sped up as well. Keep in mind that with a deficit in collagen an entire host of problems comes as well.

The web page to the following article seems to indicate degradation in the calpain/calpastatin system after freezing of carcasses even when there are variables in the equation such as marbling. Hence one could assume that marbling was not a contributing factor for Warner Bratzler shear force measurements but rather a break down in the ability of the enzyme Calpain to function after it was frozen. Another words the freezing could have denatured the proteins (destroyed the physical structure) of the enzyme thus rendering it ineffective. Enzymes function much like a key that fits into a lock, if you denature the enzyme (Extreme heat, cold, Ph changes), or in simpler terms bang on the key with a hammer, it no longer fits in the lock. If the Key no longer fits in the lock the chemical reaction, which breaks down the dead or dying muscle tissue, will not occur by this process.


As a final thought perhaps once you have identified the traits you desire you could utilize a different animal model to run your progeny testing. Something with a shorter breeding cylcle and perhaps a shorter life span will give you a higher number of progency to test for the outcomes you desire, most mammals carry similiar genes, molecules and enzymes.
Hey Ollie and others that may be interested,

Greatgerts posted a terrific website that goes along with what we are talking about. http://www.bovigensolutions.com/htm...els ! Thank you GreatGert, terrific post !
This test is great for ET work as well. A breeder in Texas has basically sold all of his cattle that have not met the high star readings and kept the rest for his ET program. Look at the site. With this technology, everybody can utilize it and have cattle that can actually keep you in the business.
If I heard right, it is Harris Riverbend Farms. They have a site on here. But, they are one of the first breeders to really utilize the GeneStar tests. I am not sure of the exact site, but like I said, it is listed on the websites on the mainpage.
I couldn't get around their sight very well . Do they have listed there or elsewhere the correlation of a one and a two star marking and the effect on tenderness?

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