IMF and Weights

[rocket2222]

Seems like I read more and more how cattle are being judged on how good they are, based on how much IMF a particular animal or herd has. Looking through sale catalogs these last few months, I've noticed most of the time in the push to get higher IMF epds, both weaning and yearling weights in most cases has dropped off quite a bit, to where just above or at breed average is now quite exceptable for a bull with a good IMF epd, to bring top dollar at many sales. This should also lower birth weights overall, which is good. I wonder though if this latest "fad" really helps the majority of commercial breeders who still sell by the pound at local sale barns or the larger retained ownership breeders who may get more per pound for their better marbled beef but still lose out on overall profit due to the loss of actual pounds of beef they have to sell.

 

[Jeanne - Simme Valley]

There is supposed to be a correlation between high IMF & light muscling. So, if that holds true, lighter muscled cattle will be weighing less. Not a trend I would be looking for, for my herd.

 

[DOC HARRIS]

rocket2222-

Your observations in the last few months are very astute - and correct! This situation relating to IMF readings and Weaning and Yearling weights is an interesting and educational study. Any correlation between %IMF and Ultrasound Ribeye Area of a sire's progeny, inasmuch as they are antagonistic traits in comparison, of necessity has an influence in marbling scores and POUNDS of weaning growth and POUNDS of yearling growth of a sire's progeny. The convoluted involvement in which producers and breeders find themselves when 'tweaking' seedstock EPD's for optimal results in matings is a "prime" example of why 'single trait' selection choices will NOT work satisfactorily - because the 'non-considered' genes DO have positive influences and at times supercede and cancel desired traits and characteristics. It is a matter of selecting the 'lesser of evils" in making final decisions.

Tough, tough job!

That is what "Antagonistic" conditions are! They are in resistance and opposition to other desirable traits, such as WW and YW EPD's. Another example are the traits Very Low Birthweights and Very High Milk Production resulting in loss of body musculature, and in particular - HINDQUARTERS! Result - FUNNEL BUTTS!

Understanding the WAYS and FUNCTIONINGS of EPD's is mandatory for a breeder to really KNOW what his herd is doing and WHY it is doing it!

I think that is the main reason why some breeders don't "- - - - believe in EPD's!" They don't understand what they are really all about, or how they work. EPD's are critrical and important, but you had better know what you are doing, and what the consequences of making a mistake can be.

The next big consideration is why smaller cows make you more PROFIT! It refers right back to your original supposition in this thread, rockett2222!

Who is going to "Bell the Cat?"

DOC HARRIS

 

[smnherf]

Interesting topic. Not just giving up weaning weight but what about giving up virility in your bulls in order to get the higher IMF score?

Time and time again, my bulls that are out running around bellering at the cows/heifers across the fence seem to have the lowest ultrasound IMF score. It is a well known fact that testosterone is negatively correlated to IMF so aren't we tending to select for lower verility bulls by selecting for a higher ultrasound IMF score?



Brian

 

[Txwalt]

Wouldn't castrating affect IMF? Not to mention artificial hormones. Is IMF as hereditary as BW, WW, and YW?

Walt

 

[waihou]

Thanks for yet more tit bits of info. regarding EPD's, or as we know them in NZ/Aust as EBV's.

Interesting about the negative correlation between IMF and weaning and yearling weights.
Even more interesting, thanks DOC, is the correlation between low BW, high milk and loss of hind quarter muscling! Must watch out when selecting with these in mind.

I am particularly interested in this one. Does that mean if you breed a well muscled animal from a cow that has both a low BW EPD and a very high milk EPD he is a 'freak' and worth keeping on as a stud prospect?

I'm particularly pleased with the way a 5 month old bull calf (MG) is shaping up from our top milk EBV cow. She is an international trait leader having a milk EBV of +16kgs to a breed standard of +3kg-sorry cannot convert but you can see she is pretty much ahead!

 

[DOC HARRIS]

Wouldn't castrating affect IMF? Not to mention artificial hormones. Is IMF as hereditary as BW, WW, and YW?

Walt

IMF and YW have a Moderate to High Heritability percentage and BW, and WW are Moderate Heritability rating. but those are percentages relating to the contemporary group of the entire breed, so it doesn't really anchor a very solid trait percentage that you can hang your hat on! But it IS another consideration to take to account.

Your question in regard to castrating and artificial hormones is something to think about! I have not seen any results of work in that regard, but I would imagine that MARC would have something on it if anyone does.

DOC HARRIS

 

[Frankie]

. It is a well known fact that testosterone is negatively correlated to IMF....

I didn't know that. Have you got some research for me to read?

 

[Brandonm2]

I am of the view that IMF and REA are probably the two biggest needs in cattle across the board, certainly the British breeds need to be looking at increasing muscle and indirectly improving Yield grade as a result. At this point, breed average growth numbers are more than sufficient; particularly if somebody is growing them out to finish out Choice. This is certainly not always true; but your high growth cattle tend to also have excessive mature weights and take longer too finish in the feedlot.

 

[greenwillowhereford II]

While I am for the cautious increase of IMF, and to some extent, REA, I would remind us that there are a number of other factors that decide the favorability of the eating experience. There are some other influences that cause (as a general rule) cattle of certain breeds to be more flavorful, tender, and juicy in Select than the average Choice. Certain breeds have a higher occurence of the DNA markers associated with tenderness than others. I am hesitant to state this, since I dread the task of digging up and finding the issue if called upon to do so, but there was an issue of Hereford America some months ago that had a copy of a study. The gist of the study was that the Hereford breed had a greater sum total of these markers across the board than any other breed in the comparison. Those other breeds I will not name at this time, as I wish to avoid a firestorm.

I have stated under another topic, there is no doubt in my mind that the thick, heavy muscled Herefords of yore were ahead of the current bunch when it came to marbling although probably not REA. The challenge to me is can we utilize these genetics without sacrificing weaning weights and milk production. I feel that there are a few breeders that have answered that challenge.

 

[KNERSIE]

Thanks for yet more tit bits of info. regarding EPD's, or as we know them in NZ/Aust as EBV's.

Interesting about the negative correlation between IMF and weaning and yearling weights.
Even more interesting, thanks DOC, is the correlation between low BW, high milk and loss of hind quarter muscling! Must watch out when selecting with these in mind.

I am particularly interested in this one. Does that mean if you breed a well muscled animal from a cow that has both a low BW EPD and a very high milk EPD he is a 'freak' and worth keeping on as a stud prospect?

I'm particularly pleased with the way a 5 month old bull calf (MG) is shaping up from our top milk EBV cow. She is an international trait leader having a milk EBV of +16kgs to a breed standard of +3kg-sorry cannot convert but you can see she is pretty much ahead!

I wouldn't say the well muscled animal that came out of a high milking cow with a low BW EBV is a freak, but he certainly isn't the rule. By using animals with these combinations of wanted traits on well muscled cows that can do with lower BW EBVs and more milk you can make quick progress in this department without sacrificing muscle.

I am a bit cautious when an EBV is that far ahead of the breed, as in the case of your cow, it seldom stays there past the first two lactations. If it does stay there, keep a close eye on her intercalving period, as soon as you go too far in any direction you'll have to lose something along the way, make sure it isn't fertility.

 

[DOC HARRIS]

Quote - "I am particularly interested in this one. Does that mean if you breed a well muscled animal from a cow that has both a low BW EPD and a very high milk EPD he is a 'freak' and worth keeping on as a stud prospect"-

waihou - I would be more inclined to think that the "well-muscled cow with low BW and very high Milk EPD" is manifesting phenotype traits, and not necessarily legitimate reproducible Genotype characteristics. It will NEVER show 100% of the resulting expectations that you would like to see! Another justification for not selecting for one trait only! Don't put all of your 'eggs' in one basket! I would not bet on a 'freak' of genetics resulting in the perfect answer for your breeding bull. His EPD's might be as mixed up as a bowl of Jello, but you wouldn't really know until he was bred to a 'bunch' of cows - and you wouldn't really KNOW even then!

I would suggest, STRONGLY, that you NOT experiment with 'freak' Genetics, just to "See what will happen!" The chances are that "What will happen" is not what you are expecting!

DOC HARRIS

 

[novatech]

What role would heterosis play?
If the genetics were equal for the desireable traits on both sides would the extra growth due to heterosis affect IMF?

 

[KNERSIE]

What role would heterosis play?
If the genetics were equal for the desireable traits on both sides would the extra growth due to heterosis affect IMF?

I doubt it would play much of a role.

 

[novatech]

What role would heterosis play?
If the genetics were equal for the desireable traits on both sides would the extra growth due to heterosis affect IMF?

I doubt it would play much of a role.

With bos taurus X bos taurus I would not think so but Bos taurus X bos indicus there is a lot more growth.
I found an interesting article on the subject but says nothing about heterosis.
http://animalscience.tamu.edu/main/acad ... smerit.pdf

I may have answered my own question after further research. Heterosis has vere little effect on quality. Given that fact along with what I have read crossbreeding is the only way to go. Seems like you could increase growth rate and size while retaining quality.
I found an interesting chart on this site.
redangus.org/index.php?option=com_docman&task=doc_download&gid=176&Itemid=164 -
Sorry you will have to copy and paste.

 

[SEC]

. It is a well known fact that testosterone is negatively correlated to IMF....

I didn't know that. Have you got some research for me to read?

Any stud book, i.e. Precision, New Design, Prime Time's, etc.

Not only are genetic defects worrysome but the lack of crest and character in many of the animals.

 

[Frankie]

. It is a well known fact that testosterone is negatively correlated to IMF....

I didn't know that. Have you got some research for me to read?

Any stud book, i.e. Precision, New Design, Prime Time's, etc.

Not only are genetic defects worrysome but the lack of crest and character in many of the animals.

Not exactly what I had in mind.

 

[Frankie]

Wouldn't castrating affect IMF? Not to mention artificial hormones. Is IMF as hereditary as BW, WW, and YW?

Walt

Steers marble better than bulls, so I'd assume that castration affects IMF. But I'd sure like to see some research.

 

[DOC HARRIS]

Wouldn't castrating affect IMF? Not to mention artificial hormones. Is IMF as hereditary as BW, WW, and YW?

Walt

Steers marble better than bulls, so I'd assume that castration affects IMF. But I'd sure like to see some research.

Frankie-

Try "MARC".

DOC HARRIS

 

[MikeC]

John Brethour:

There has been a concern that selection for higher
marbling in bulls might also be associated with reduced testosterone levels.

Also:

It is difficult to perform accurate research on marbling. The trait is not distributed
according to the Gaussian (bell shaped) curve (Figure 3) so conventional statistics are not
appropriate to analyze results. (This probably has resulted in some scientists erroneously
concluding that marbling did not differ among treatments.) Serial slaughter is confounded
with time and conditions for collecting marbling scores may vary at different slaughter dates.
Marbling is a subjective measure of the visual assessment of the appearance of rib eye face.
Variations among graders of 0.6 to 0.8 average marbling score units have been documented.
Also, it is very important that the carcass be thoroughly chilled before marbling is recorded.
Marbling scores may vary according to whether the carcass was kept in an area where
chilling was effective or along a wall where air circulation was poor.
Because marbling scores tend to cluster in the High Select and Low Choice
categories, each 0.1 increase in marbling score may be associated with as much as 7.6
percent increase in percent Choice in a group of cattle.

http://www.wkarc.org/Arch/Research/catt ... asound.pdf