Heritability estimates

[alexfarms]

Here is an article on heritability estimates of fertility in beef cattle.

http://jas.fass.org/cgi/content/abstract/67/10/2589

To summarize a bit, it states various studies have concluded that cow fertility heritabiliy estimates range from a high of .17 to a low of .01. The article concludes: "Heritability estimates in this study are in agreement with the literature, indicating little opportunity for improvement in pregnancy rate by selection within a breed". Heritablity estimates for cow fertility are very low.

Here is an article on Heritability estimates of carcass traits in beef cattle.

http://www.funpecrp.com.br/GMR/year2004 ... l_text.htm

To summarize a bit, the article states most of the carcass traits are moderately heritable, rangeing from .37 to .40, and Yield grade is highly heritable at .64. In referring to Yield grade's high heritability estimate the article states: "indicating that this carcass trait is highly heritable and genetic merit might be improved through selection."

SO, AS SEEDSTOCK PRODUCERS, WHICH TRAITS SHOULD WE BE SELECTING FOR MOST DILIGENTLY: Cow fertility or carcass traits?

 

[Herefords.US]

I've had several long time Hereford breeders, whose opinions I do respect, advise me that because cow fertility heritability is so low, that it is the trait that should be selected for and culled against most diligently.

George

 

[ANAZAZI]

We must select for both. When it comes to fertility there is not so much hertability as there is genetic diversity; i.e the best are far better than the worst. However; there needs to be enough progeny to test it quickly. There is anyway a possibility for any breeder to cull for this trait, and make some progress.

 

[dun]

I've had several long time Hereford breeders, whose opinions I do respect, advise me that because cow fertility heritability is so low, that it is the trait that should be selected for and culled against most diligently.

George

My old mentor (dead now for 30 years) selected for feet & legs, fertility then milk production. He was a dairyman. Had cows in his herd making serious money for him into their teens. His cows got 2 trys at AI, if they didn;t settle they wenty down the road at dry off. Takes time but it eventually leads to cattle that are fertile and breed back quickly. Daughters of our fast settling (first service) cows tend to be also fast settling . Maybe it's just cow familys, but I tend to believe it's the selection for fertility that we've alwasy practiced.

 

[novatech]

In my book fertility is number 1. No calf equals no sale. No matter how good or bad.
Once a fertile herd is established the highly heritable traits can be put in place.
Herd fertility is more than genetics. Fertility and other traits, low in heritability, are effected a great deal by the environment, which includes more than just where they live.
A good article.
https://transact.nt.gov.au/ebiz/dbird/T ... le/794.pdf

 

[SRBeef]

In my book fertility is number 1. No calf equals no sale. No matter how good or bad.
Once a fertile herd is established the highly heritable traits can be put in place.
Herd fertility is more than genetics. Fertility and other traits, low in heritability, are effected a great deal by the environment, which includes more than just where they live.
A good article.
https://transact.nt.gov.au/ebiz/dbird/T ... le/794.pdf

I absolutely agree. Whether heritable or not, no calf = no pay. Fertility is #1 in importance in cow/calf. Otherwise its just cow!

My plan is that if a cow does not calve within two cycles = 45 days of the first calf she is gone. I want almost all to calve in ONE cycle = 22 days which I now see is possible with a small herd in a small area with a good bull as mine are. Mine all calved within 21 days this spring.

Because of logistic limitations I have to leave my bull in with the girls until January or thereabouts but I still don't want any stragglers.

Jim

 

[alexfarms]

I pretty much agree with most of the responses. I know we have to select and cull for everything, but it seems to me like if the carcass traits are more highly heritable, then they will be easier to change and that makes them less important. I don't think the functional traits, which are less heritable, should be compromised on since they are more difficult to change. In today's marketplace so much emphasis is being placed on show ring winners and epd toppers and both of those programs seem to reward the carcass traits. The profitablility index that the AHA has come out with are an attempt to wrap it all together, but I don't think they are well understood or proven...yet. JMHO>

 

[BeefmasterB]

In my book fertility is number 1. No calf equals no sale. No matter how good or bad.
Once a fertile herd is established the highly heritable traits can be put in place.
Herd fertility is more than genetics. Fertility and other traits, low in heritability, are effected a great deal by the environment, which includes more than just where they live.
A good article.
https://transact.nt.gov.au/ebiz/dbird/T ... le/794.pdf

Fertility though, is low on the inheritablility trait list. Culling appears to be the best option, provided the environmental factors were well managed. But first, I would think a breeding soundness exam would be a must for any herd bull(s) to eliminate potential problems there.

Another link to heritability estimates:
http://www.extension.umn.edu/distributi ... I3926.html

 

[Frankie]

While I'd never argue that fertility isn't the most important trait for a cow, that's not how we select our replacements. I've seen daughters of pathfinder cows that wouldn't settle. We've bought cows that didn't get bred to calve as a two year old, or didn't settle back after her first calf, and they've been solid, reliable producers for years. Management plays a big role in fertility.

Because fertility is a low heritability trait, it's very difficult to use it as a selection tool. We keep it in mind, but select replacements/bulls based on other traits first.

 

[HerefordSire]

Here is an article on heritability estimates of fertility in beef cattle.

http://jas.fass.org/cgi/content/abstract/67/10/2589

To summarize a bit, it states various studies have concluded that cow fertility heritabiliy estimates range from a high of .17 to a low of .01. The article concludes: "Heritability estimates in this study are in agreement with the literature, indicating little opportunity for improvement in pregnancy rate by selection within a breed". Heritablity estimates for cow fertility are very low.

Here is an article on Heritability estimates of carcass traits in beef cattle.

http://www.funpecrp.com.br/GMR/year2004 ... l_text.htm

To summarize a bit, the article states most of the carcass traits are moderately heritable, rangeing from .37 to .40, and Yield grade is highly heritable at .64. In referring to Yield grade's high heritability estimate the article states: "indicating that this carcass trait is highly heritable and genetic merit might be improved through selection."

SO, AS SEEDSTOCK PRODUCERS, WHICH TRAITS SHOULD WE BE SELECTING FOR MOST DILIGENTLY: Cow fertility or carcass traits?

Does anyone know what pedigree lines were used for the initial stock in the fertility document? There could be a wide fluctuation in fertility rates depending upon the herds selected from such as garbage in and garbage out. I do not think this was addressed in the document but I may have overlooked it. Is this a factor in determining heritability rates of fertile stock?

Data were available from three herds of
beef cows maintained from 1970 to 1986 at the
University of Arkansas Beef Cattle Research
Unit. Observations included matings of 2,611
Angus, 813 Hereford and 1,101 Polled Herefords

http://jas.fass.org/cgi/reprint/67/10/2589

 

[HerefordSire]

Here is an article on heritability estimates of fertility in beef cattle.

http://jas.fass.org/cgi/content/abstract/67/10/2589

To summarize a bit, it states various studies have concluded that cow fertility heritabiliy estimates range from a high of .17 to a low of .01. The article concludes: "Heritability estimates in this study are in agreement with the literature, indicating little opportunity for improvement in pregnancy rate by selection within a breed". Heritablity estimates for cow fertility are very low.

Here is an article on Heritability estimates of carcass traits in beef cattle.

http://www.funpecrp.com.br/GMR/year2004 ... l_text.htm

To summarize a bit, the article states most of the carcass traits are moderately heritable, rangeing from .37 to .40, and Yield grade is highly heritable at .64. In referring to Yield grade's high heritability estimate the article states: "indicating that this carcass trait is highly heritable and genetic merit might be improved through selection."

SO, AS SEEDSTOCK PRODUCERS, WHICH TRAITS SHOULD WE BE SELECTING FOR MOST DILIGENTLY: Cow fertility or carcass traits?

Based upon the documents only without intense study I am thinking the following could be accurate....

If you bred 100 cows and 17% (17 - 0) was the maximum variance related to fertility inheritance, then the most you could lose related to inheritance would be 17 new animals per year.

If you bred 100 cows and 3% (40 - 37) was the maximum variance of carcass trait inheritance, then it may only take one or two animals to make up the diference per year. In order to figure this out exactly, you would need total carcass weight for a crop year for comparison purposes.

Therefore, the inheritance in fertility is much more important at the upper end of the range and much less important at the lower end of the range. So if you had 8.5% of your cows coming up open related to inheritance, then it could pay to make further investments in fertility genetics. If your fertlity inheritance rates were 2%, then further investment in fertility genetics would probably not make a profound difference relative to further investment in carcass genetics.

 

[bigag03]

Herefordsire,

Isn't that what several others have already stated? Since fertility is the hardest to change, put an emphasis on it until you have a handle on it. Once you feel like you have successfully got a handle on fertility, then make changes that can occur more rapidly. Now with that being said, all characteristics should be kept in mind during all breeding decisions (i.e. don't single trait select). If you send your carcass traits down the drain for sake of fertility, you will have a taller hill to climb once the fertility is where you want it, and if you ignore fertility once you have it where you want it, it will soon start to suffer.

 

[ANAZAZI]

I was so lazy when I posted, for reasons; the matter is complicated, and it is difficult to explain itnot using my own language.
I will try anyway. When the fathers started breeding for fertility in the early seventies (The national programme for AI cattle and milk testing in the swedish red breed), they were ridiculed internationally because they bred for something with low heritability. But our genetical experts found out that as long as the breed has great diversity (or variance) for the trait, and as long a progeny groups are big enough, it works, because this sorts out the environmental effects. So to determine fertility, calving ease, birth ease and general decease resistance, it was established that each bulls daughter group should be close to two hundred, and spread out in all of the country to sort out the environmental effects of different herds. These large groups of progeny also gives exellent information on the milk conformation and slaghtering data. To this day our dual purpose breed have efficiently been bred for fertility as well as milk, beef conformation and general health. This breeding for fertility with large groups of progeny have preserved the original fertility while improving milk and beef, while other breeds in the world (for example holstein) compete in milk but experience an ever dwindlig fertility. For beef breeds this tendency that the fertility weakens, is slower and easier to handle, but the problem needs to be adressed, and AI bulls are preferably chosen from fertile cows and progeny tested on enough females. My two eurocents!

 

[HerefordSire]

Herefordsire,

Isn't that what several others have already stated? Since fertility is the hardest to change, put an emphasis on it until you have a handle on it. Once you feel like you have successfully got a handle on fertility, then make changes that can occur more rapidly. Now with that being said, all characteristics should be kept in mind during all breeding decisions (i.e. don't single trait select). If you send your carcass traits down the drain for sake of fertility, you will have a taller hill to climb once the fertility is where you want it, and if you ignore fertility once you have it where you want it, it will soon start to suffer.

Looks like I made a unique attempt to associate the two variables mathematically: fertility heredibility and carcass trait heredibility.

.03 * .17 = .0051 maximum variance factor. Figuring out what to multiply the factor to would be the hard part. If zero cows were open, then I think the fertility heredibility could be proven relatively easy. The point of the question I think would be to distinguish the difference for future improvement and or investment based upon scientific data.