Puberty vs. Rate of Maturity

[IluvABbeef]

This may seem like a dumb question to some of you (it does to me), but after doing some reading I got a bit confused after reading about a particular breed (Gelbvieh) being capable of having early puberty, and yet is normally an moderate to late-maturing breed. This seems very counter-intuitive to me because I'm thinking that the rate of puberty is equivalent to the rate of maturity, so when I read something like that I get confused. So what's the difference?? Am I right in my thinking, or completely off?

ETA: What's the relevance of length of gestation to rate of maturity or puberty? Is it even related or something different that can really confuddle up things?

 

[dun]

As in people puberty and maturity are 2 totally different issues. Apples & oranges

 

[IluvABbeef]

I'm not talking about people puberty, dun, I'm talking about heifer/bull puberty. There's sexual maturity = puberty then maturity.... :?

 

[IluvABbeef]

This is where I read it:
http://www.thecattlesite.com/breeds/bee ... h/overview

 

[KNERSIE]

You're confusing carcass maturity with sexual maturity.

After the onset of puberty a heifer should be cycling (be it regular or not) and should be able to conceive, but it doesn't neccessarily mean she is sexually mature. Carcass maturity is when the long bone growth has slowed down sufficiently for the animal to lay down fat instead of just putting all the available nutrients towards growth. A finished steer refers to such an animal which has laid down sufficient fat to grade at the desired level.

Off course my explanation is somewhat simplified, but I think you'll get the general idea.

 

[dun]

I'm not talking about people puberty, dun, I'm talking about heifer/bull puberty. There's sexual maturity = puberty then maturity.... :?

I know you were talking about cattle, but the same applies. Puberty isn;t maturity either for growth or reproductive, it just means they can reproduce but just because they can does mean their mature enough to be doing it.

 

[Keren]

I can see where you are coming from Iluvabbeef ... when I was at uni we were taught that the onset of puberty was linked to body weight, I think it was about 60% of their mature weight is when they will hit puberty (or it might be less than that, the 60% might have been when its safe to breed them ... )

Anyway, seems to me that if puberty is dependant on body weight, then late maturing cattle breeds surely would be later to hit puberty ... as it would take them longer to reach their 60% of mature weight or whatever ...

Hope I'm making sense here, I'm confusing myself

 

[3waycross]

Too address a part of your original post. My Vet told me a while back that when she was in school they had Gelbvieh heifers that they observed to be cycling at the age of 4 months, and this was the rule rather than the exception.

 

[IluvABbeef]

Okay, let me get this straight here...puberty is not correlated to maturity (being carcass maturity, not adult maturity, which would be the period when growth slows to the point that the animal no longer is or needs to grow) because puberty is merely to do with fertility or rate of reproduction, not growth. So with Gelbvieh, they are able to start coming into heat at around 4 to 5 months, as you mentioned 3way, but are moderate or slow to mature as in they take longer to put on fat simply because they're still putting down muscle and not fat.

Ahhhh....okay, I see it now. :idea: :idea:

Now my second question is how does this factor into length of gestation, or is it another apples vs. oranges thing I'm bringing up here?

 

[dun]

Okay, let me get this straight here...puberty is not correlated to maturity (being carcass maturity, not adult maturity, which would be the period when growth slows to the point that the animal no longer is or needs to grow) because puberty is merely to do with fertility or rate of reproduction, not growth. So with Gelbvieh, they are able to start coming into heat at around 4 to 5 months, as you mentioned 3way, but are moderate or slow to mature as in they take longer to put on fat simply because they're still putting down muscle and not fat.

Ahhhh....okay, I see it now. :idea: :idea:

Now my second question is how does this factor into length of gestation, or is it another apples vs. oranges thing I'm bringing up here?

I think it's more of a bananas vs peaches kind of deal. Typically what we've seen through the years is the shorter gestation calves are smaller at birth which makes sense. But we have used some bulls that have calves born usually a week to 10 days shorter then other bulls. I
ve never noticed their daughters being any slower to start cycling or conceiving.

 

[regolith]

I can see where you are coming from Iluvabbeef ... when I was at uni we were taught that the onset of puberty was linked to body weight, I think it was about 60% of their mature weight is when they will hit puberty (or it might be less than that, the 60% might have been when its safe to breed them ... )

Anyway, seems to me that if puberty is dependant on body weight, then late maturing cattle breeds surely would be later to hit puberty ... as it would take them longer to reach their 60% of mature weight or whatever ...

Hope I'm making sense here, I'm confusing myself

60% is probably when they're safe to breed. From the activity I'm seeing every day I doubt I've got a weaner *not* cycling and they shouldn't have reached 50% of their mature weight yet.
Although vet articles on heifer rearing try to scare farmers by telling them if their heifers don't meet those target weights at 15 mths they might not be cycling early enough to calve with the group, none of my experience supports that view. Dairy heifers are as precocious as Gelbvieh. (round about way of saying that the vets are telling us that puberty kicks in very close to breeding time, experience doesn't bear that out)

Gestation length is highly hereditary - it's one of the easiest things to breed for. I don't know if it's linked with anything other than undercooked calves.

 

[IluvABbeef]

Understood. Thanks.

 

[djinwa]

Just to confuse things.

Carcass and reproductive maturity may be separate traits, but I would think that would assume adequate energy to support both.

In a situation where energy is restricted, supporting growth takes priority over reproducing, so a higher growth, later maturing female might reach puberty later?

Just as in high producing dairy cattle which are in a negative energy balance (physiologic starvation) and have more trouble breeding back because the first priority is to save self before reproducing.

I am now recalling the article you posted on limit feeding heifers to delay the age of reaching mature weight. I would think that wouldn't have caused reproductive delay, so maybe my thinking is off. Perhaps the energy restriction has to be more severe to delay puberty.

 

[IluvABbeef]

I would think so, DJ. The article had had the heifers on a more roughage-type diet with higher fiber over protein/energy feedstuffs which made them reach a mature weight more slowly than what is usually done to grow replacement heifers. All they (John and Adele Popp of Erickson, MB) did was restrict the heifers' rate of gain in order for them to reach a smaller terminal weight. And these were Simmental-Angus heifers, not just british-bred heifers, so these heifers, on a normal replacement feeding program, would gain more and grow into larger heifers than the Popps had them to do, simply by limiting supplementation.

Now how this factors into the puberty part of the equation is where it gets a little interesting. The article states this:

According to the paper [written by Funston, his associate Jeremy Martin, and Andy Roberts of the Fort Keogh lab, "Heifer Development--Then and Now"], most research reports up until the late 1980s continued to show that limiting post-weaning growth had a negative effect on age of puberty and pregnancy rates.

Around the late 1980s, reports began to reveal that the association between body weight, puberty and heifer pregnancy rate had changed, Subsequent studies indicated that delaying heifer gain until two to three months prior to breeding season reduced the amount of feed required, while calving rate, age at calving, postpartum interval, and second-year pregnancy rate were not affected.

.....

In 2004, Funston was involved with a study showing that heifers developed to reach either 53 or 58 per cent of mature rate prior to breeding had similar pregnancy rates from the initial breeding through the fourth breeding.

Continuing with the same herd, Martin found that extending the breeding period from 45 days to 60 days for heifers developed to weights as low as 51 per cent of mature weight at first breeding resulted in similar first-calf conception rates and no difference in second-calf conception rates than the group developed to 57 per cent of mature body weight at first breeding.

I believe this paper may have some relation to the quoted article above: http://www.ianrpubs.unl.edu/epublic/liv ... /rb350.pdf

So there you go. All the whole thing was about limiting feed for replacement heifers was to save on feed, nothing to do with anything affecting puberty, conception rates nor gestation.

 

[hillsdown]

As far as GV I have found that the ones that reach puberty at around 4-5 months are the also the ones that end up getting Dam of Merit awards. They breed back on time and have above average ween weights ,and usually by the time they are 6 ,I end up with a set of twins from them . Their daughters usually will carry on the same easy fertility trates .