Calf size in an ET program

[WalnutCrest]

We all know that embryo calves are bigger than AI/live cover calves. I found myself wondering if there was anyone here who knew how much of that is related to some sort of "in utero heterosis" of using recips of a different genetic makeup than the donor.

Said another way ... and in a hypothetical situation ... would you expect the average BW of calves from group 1 to be any different than the BW of calves from group 2?

If your donor (European Breed X) is flushed multiple times to the same bull of the same breed. All eggs are frozen to implant later.

Group 1 = 20 recips all confirmed carrying embryo calves where the donor is a full or half sister to the recips ... ten heifers and ten bulls are coming ... all embryos and recips are pedigreed Breed X (European breed)
Group 2 = 20 recips all confirmed carrying embryo calves where the donor is very very unrelated to the recips ... ten heifers and ten bulls are coming ... all embryos are European Breed X, the recips are straight brahma (for example)

Will the BWs vary materially? If so, any idea how much of it could be chalked up to some sort of in utero heterosis?

 

[Lucky_P]

We don't ALL 'know' that. Documentation, please.

Some recips will provide an advantage to the calf - at birth and afterward - above what the donor might in a natural pregnancy, some don't.

 

[WalnutCrest]

We don't ALL 'know' that. Documentation, please.

Interesting.

I have discussed BW of ET calves with numerous people who have extensive experience with emrbyo work. To a man, they all told me that ET calves are bigger at birth than AI or natural service calves. I never thought to go look it up; they were so consistent in the tone and nature of their comments it never occurred to me to second guess them.

So, today I did look it up at your suggestion.

It appears that some research says there is no difference; some research says there is.

Here's one report (http://www.journalofdairyscience.org/ar ... 22-0302(13)00748-0/pdf) showing a difference in Holstein -- AI vs. ET-fresh vs. ET-frozen -- birth weights of 41.7kg vs. 42.5kg vs. 45.3kg (respectively) and gestation lengths of 274.9 days, 275.0 days and 279.5 days, respectively.

It would appear that the BW differences might stem more from whether or not the embryos were frozen before implant, or transferred fresh.

If you have any research or personal experiences to share, I'd love to hear them.

Thanks.

Some recips will provide an advantage to the calf - at birth and afterward - above what the donor might in a natural pregnancy, some don't.

Yes. I agree...

*****************************

My question still stands ... does anyone have any ideas/theories about whether or not there is an in-utero heterosis effect that would influence the size of the calf ... should you use recips of the same breed as the donor to moderate BW's ... or does it matter?

 

[branguscowgirl]

I do not know for a fact, but I would assume that (like Lucky_P stated) each recip would nourish and grow a calf differently. In utero and on the ground. :2cents:

 

[Son of Butch]

I do not know for a fact, but I would assume that (like Lucky_P stated) each recip would nourish and grow a calf differently. In utero and on the ground. :2cents:

Bova a holstein bull at Select Sires was the 1st ever ET calf.
The recip was a Jersey cow and Bova had a small mature size for a holstein bull...but did not pass that trait on to his offspring.
[speculation was his mature size may have been stunted by using a Jersey as recip]

Shortly after I had a friend who had a holstein cow A.I. studs wanted a bull from.
His uncle was a Vet and decided to try his hand at ETs...he transferred the eggs into black angus heifer recips...
all were heifer calves colored like holsteins but when they matured into milking cows all had more of a round bone
in their rear leg like a beef cow, rather than the flatter clean hock of a dairy cow.
They all were a bit courser and beefier than he expected from that mating and he always blamed it on the angus recips.

Because of the value of ETs, I would think most recips would probably be babied a bit more with better
nutrition while pg than average and that would result in higher birth weights too.

 

[WalnutCrest]

I do not know for a fact, but I would assume that (like Lucky_P stated) each recip would nourish and grow a calf differently. In utero and on the ground. :2cents:

Bova a holstein bull at Select Sires was the 1st ever ET calf.
The recip was a Jersey cow and Bova had a small mature size for a holstein bull...but did not pass that trait on to his offspring.
[speculation was his mature size may have been stunted by using a Jersey as recip]

Shortly after I had a friend who had a holstein cow A.I. studs wanted a bull from.
His uncle was a Vet and decided to try his hand at ETs...he transferred the eggs into black angus heifer recips...
all were heifer calves colored like holsteins but when they matured into milking cows all had more of a round bone
in their rear leg like a beef cow, rather than the flatter clean hock of a dairy cow.
They all were a bit courser and beefier than he expected from that mating and he always blamed it on the angus recips.

Interesting.

Because of the value of ETs, I would think most recips would probably be babied a bit more with better
nutrition while pg than average and that would result in higher birth weights too.

Very good point.

A higher plane of nutrition while preggo sure could explain an increase in BW. A good idea I'd not thought of...

 

[TexasBred]

Because of the value of ETs, I would think most recips would probably be babied a bit more with better
nutrition while pg than average and that would result in higher birth weights too.

Very good point.

A higher plane of nutrition while preggo sure could explain an increase in BW. A good idea I'd not thought of...

Higher energy and protein levels fed during the last couple of month sof pregnancy give large variations in birthweights. Sometime no larger, sometimes larger, depending on many factors. Research has shown that the cows is definitely in better shape for birthing, produces more milk and weans a larger calf. Feed, weather, location can all come into consideration. Just too many variables for a simple study to produce reliable results.

 

[WalnutCrest]

I guess I've been focusing on genetic causes that are probably too variable to be able to reliably study.

:hide:

Thanks.

 

[Lucky_P]

I don't know... just stating that we don't all know your original assertion to be fact.
You could be right... or not.

I suspect SOButch is probably on the right track. Higher dietary protein levels in the third trimester usually translate into higher birthweights - but not necessarily an increase in dystocias.
I know if I had some recips carrying embryos that I considered to be more valuable than my other calves, I'd probably be treating them a bit better than the other cows in the herd.

 

[WalnutCrest]

I don't know... just stating that we don't all know your original assertion to be fact.
You could be right... or not.

I suspect SOButch is probably on the right track. Higher dietary protein levels in the third trimester usually translate into higher birthweights - but not necessarily an increase in dystocias.
I know if I had some recips carrying embryos that I considered to be more valuable than my other calves, I'd probably be treating them a bit better than the other cows in the herd.

So...dial up the nutrition for the first two trimesters and then back off a bit so that you don't ask a normal sized cow to birth an elephant?

Or, don't do anything too extraordinary until the instant that calf hits the ground, then give mama access to the "good stuff" (whatever that is)?

Or, feed her well all the way through, and expect her to deal with the possible behemoth that's growing inside her?

...what is the best thing for that calf?

Not really asking you per se ... just wondering with the ends of my fingers on a keyboard ...

 

[TexasBred]

Just treat them like any other pregnant cow. Adequate nutrition and care from start to finish.

 

[WalnutCrest]

Just treat them like any other pregnant cow. Adequate nutrition and care from start to finish.

That's my inclination, too. Nothing extra or fancy.

***********************

... still thinking about in utero heterosis for embryos implanted in another breed of cattle ...

 

[Lucky_P]

Colder weather than normal - like we had this past winter - results in larger birth weights. And, due to poor hay quality, we were feeding nearly double the amount of DDG we'd originally calculated we'd need. Birthweights on calves from mature cows averaged 96# - bulls and heifers were pretty close to the same. No dystocias, other than one that had an elbow hung. I don't normally weigh calves, so don't really know what my calves usually run, but we were doing a progeny-test breeding trial for a seedstock producer and had to collect BWs; those suckers were all quite a bit larger than I was accustomed to - and we'd used one of the bulls previously.

 

[Fire Sweep Ranch]

Just treat them like any other pregnant cow. Adequate nutrition and care from start to finish.

Our recips are in the same pasture and eat the same grass as our AI bred cows. They are treated no different. We have not found higher birth weights, but we do find shorter gestations typically on embryo calves. Another thing to ponder.... :lol: :2cents:

 

[polledbull]

my experience is that some ET calves (recips) will have a longer gestation, , they can go overdue by several days , I have seen them go over by 8-10 days past the due date , this may lead to the bigger calves from ET notion

 

[WalnutCrest]

So, to sum up ... your ET calf may be shorter gestation or longer gestation. It may be larger than expected or smaller than expected. These things might be related to the nutritional plane of the mother while pregnant, it might be the genetics of the specific calf, it might be some sort of in-utero heterosis between the embryo and the recipient, it might be some combination of all of these things ... or it might be none of them at all.

Gotcha.

 

[Nesikep]

And it's all very scientific!

From my understanding, Heterosis, or 'hybrid vigor', is the extra growth an individual shows because of of it's parents of different breeds, and is genetic... In the case you're describing, the difference is between the calf and it's recip mother, but that wouldn't be a genetic thing and I don't think you could classify it as heterosis.

As for birthweights, 6 years ago our average birthweight was around 80ish lbs, give or take a couple for heifers or bulls, the next year ,our average BW jumped up to just shy of 100 lb, same calving season, same hay, same cows, and same bull, it hasn't come down since and we're going on our third bull since then.. don't know why, just happened.

 

[midtncattle]

I had an AI calf delivered 11 days past conception date last year . Had to be ai sired because no bull and no bulls close. How much extra weight do you think that added to the calf .

 

[Katpau]

What do you consider 11 days past? Are you using 276 days?, 281 days?, 283 days?, 285 days?, 288 days? Depending on the chart you use, all of these are normal gestations. Different breeds have different numbers they consider average. I have cows that routinely carry for about 276 days and others that are closer to 290 days.

 

[Nesikep]

I really doubt your calf was born 11 days past conception!.. or it wasn't much of a calf.

I found my cows carry an average of 288 days, bull calves always a little longer than the heifers. Longest gestation I ever recorded was 302 days, normal size bull calf.. talk about a waiting game with that one!