Igenity testing

[grassfarmer]

This topic was raised in the Spring but I wonder if anyone has any comments on the tests or where they see their role in purebred cattle breeding. I'm intrigued by the concept but can't get my head around what it's use is.
As I see it one drug corporation (Merial) has patented this test on the assumption that purebred breeders will use it, breed animals with better carcase traits as a result and hope to improve their bull sale prices as a result. This assumes that commercial cow/calf guys will seek out and spend more on bulls with these traits. It looks like technological progress - if it pans out it could be the biggest breakthrough in cattle breeding since Bakewell. But..... what effect will it have on purebred herds if they suddenly select intensively for carcase traits - bearing in mind that the females still have a job to do rearing calves? Will there really be any benefit to cow/calf producers if they don't retain ownership of their cattle through to fat? I'm reminded of the 10:2:1 rule of profitable cow/calf production that I read somewhere which states:
" Fertility traits are 10 times more important than carcase traits and 5 times more important than growth traits."
Any thought on who stands to benefit from this technology?

[jensend]

Any thought on who stands to benefit from this technology?

maybe merial

[15444]

It's a tool and nothing else. Some of the Hereford people have tried to sell their bulls to me with their sole arguement floating around how the animal's Igenity results came back.

Personally, if I had money to burn, I would test every cow and bull in the herd once and then use the info I get back as a tool in culling decisions. Remember, it's a gene thing, so if you used it you could ideally take your herd from producing 50% leptin-gene calves to 80-90% leptin-gene calves in a short time. Of course a few leptin negative cows would stay in the herd or at least I hope nobody would be stupid enough to get rid of good, healthy, young-looking herd builders just because of the results. Only get rid of the cows that just need that little extra to devalue their contribution to the herd.

Don't question the Hereford people about it at the cattle shows though, please, or the next 3 years will circle around Herefords becoming the breed with the highest percentage of leptin positive cattle in Canada....while the truly important traits take a backseat.

[cakadu]

15444, could you please explain a little about what this leptin trait is please?

Thanks.

[15444]

Took bits and pieces from a site independent of Merial as I don't trust Merial's propaganda.

Leptin is a protein hormone with effects in regulating body weight, metabolism and reproductive functions.

As adipocytes (fat cells) increase in size due to accumulation of triglycerides (fats), they synthesize more and more leptin.

Leptin's effects on body weight are mediated through effects on hypothalamic centers that control feeding behavior and hunger, body temperature and energy expenditure.

<u>Interestingly grassfarmer:</u> Leptin concentrations are low in people and animals with low body fat, and <b>leptin appears to be a significant regulator of reproductive function.</b> These effects are probably due in part to the ability of leptin to enhance secretion of gonadotropin-releasing hormone, and thus luteinizing and follicle-stimulating hormones from the anterior pituitary.

This PDF file from Merial probably helps to give you a visual of how leptin works:
http://ca.igenity.com/pdfs/Intro_Leptin3004_Eng_04.pdf

Basically, the prescence of the <b>tt</b> Leptin gene allows the animal to keep eating without any signals of being 'full' , reaching the brain. So the animal keeps on eating and produces more leptin through the deposition of fat into fat cells. So the animal eats increasingly more and more feed and obtains more fat.

The <b>cc</b> Leptin gene does the opposite, meaning the signals of being 'full' reach the animal's brain and then it quits eating until it is hungry again. This means that the animal doesn't consume more feed then neccessary and doesn't gain a large amount of fat cover.

[15444]

I forgot to add that experiments done with mice found that the mice that were homozygous for leptin were obese at a young age, but also reached sexual maturity much earlier then mice that were heterozygous for leptin.

So, upon learning this interesting little tidbit on fertility, leptin might prove to be a bit more important then I originally thought, although it still is only a tool in cattle selection in my mind.

[Cedar]

Grassfarmer:

"what effect will it have on purebred herds if they suddenly select intensively for carcase traits"

Guess that's the unknown part, we get to be the guinea pigs again! Assuming this test proves to be accurate, I could see the end result being that carcass traits become the new "have to have it" fad, just as super growth rates have been in the past. Where did that get us in the end? It never seems to fail that when we select too strongly for any one (or even two) traits, nature dictates that we must give up something in the other traits. Straying too far from the well balanced animal never pays....at least not for the primary producer. But it seems the rest of the industry "links" always have to demand certain characteristics in the animals, and they always get what they want when they decide to pay more for it. Then, once everyone has switched over to supply what they demand, of course supply and demand kicks in and prices...um...adjust!

"Any thought on who stands to benefit from this technology?"

Ultimately....dare I say it??? ... the ....packers!!!! And, of course, once again, it's us who has to pay for it!

Imho, long term survival (and success) depends on keeping a close eye on your bottom line (the net...not the gross), and really watching the traits showing up in various animals and culling accordingly. For example, the highest weaning or yearling weight heifer might not necessarily wind up to be your best cow...in fact, she might be your worst. Sometimes, if you really watch your genetics, you can find those "little wonders" who aren't too big themselves, but will produce a great calf every time....lower feed bill and higher profits....wow, what a combo!

[Cedar]

15444:

Interesting, however I have to wonder....well, we know what obesity does to people, especially at a young age...so, what will the end result of selection for this trait in cattle be? Will our bovines be dropping dead of heart attacks by age 5? Hmmm...especially these days, seems to me longevity is a lot more important than that!

[Cedar]

15444:

So, does this leptin gene have anything to do with the natural ability to produce marbling in the beef (if there is such a thing) or does it simply indicate an animal that doesn't know how to turn off the "hunger button"???? Does eating more actually produce better marbling??? I think I'm confused!

[nerves]

Grassfarmer would add that certain breeds produce more fat than others and they also produce less meat. Then there are breeds that produce red meat but will have less fat. Now if you could find an exotic animal that can produce the meat but can also add marbling then cross them with a british breed type then you should have excellnt carcass animal. You can have animals that are fertile, have feet that do not ever crack or need to be trimmed, are heavy milkers, easy keepers and longevity. We are lucky enough to have one in our herd she is a year Z and is leptin TT the best cow on the place and she is Charolais. We have every daughter she has ever raised and a local rancher buys every bull she has ever raised. We finaly kept a son for ourselves, and we now use three leptin TT bulls of differnt blood lines in our herd. We believe there is merit in it as we finish and sell our yearlings direct to the customer. We also notice less trim on these animals when finished as compared to a staight british bred animal when finished. The butcher charges by the hanging weight so less trim and more meat with marbling is ideal for us. In our opinion it is the future of the livestock industry in North America.