Scrotal Circumference

[allisonr]

So I heard that a large scrotal circumference in bulls leads to early maturity/growth in his female offspring. Is this a valid rule of thumb? And if so, what is a "good" SC? When reading EPD charts, they are listed as +/- 0.56 for example. How is this read? Thank you in advance

 

[wbvs58]

I don't think the EPD figure would have little relevance to the actual bull in question. I would pay more relevance on the actual raw data measurement which at bull sales is usually on a supplementary sheet or from what you or the vet measure during a BSE. Breed societies will give minimum recommended scrotals at the various ages. With 2 yr old Angus bulls I would consider 43cm as a pretty fair size, I like mine to be at least 38cm but I am more comfortable with 40 and over.
Ken

 

[Boot Jack Bulls]

As said, actual individual performance is useful. NALF suggests all Limi breeding bulls measure at least 32 cm at 1 year. We shoot for a 38, and those that are not under 34 don't keep them for long. Our semen tech actually recommends 38 as the target for the Limis, but suggests anything over 42 or so may be too big for that age.

 

[Nesikep]

I think it depends (especially on yearling bulls) on their overall size, which depends on their feed regimen too.. They have to be proportional to their physical size.. a 38cm on a 2800 lb bull isn't the same as on a 1400 lb bull.

 

[WalnutCrest]

I think it depends (especially on yearling bulls) on their overall size, which depends on their feed regimen too.. They have to be proportional to their physical size.. a 38cm on a 2800 lb bull isn't the same as on a 1400 lb bull.

+bajillion

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

Same bull calf on creep and grain will have different scrotal than if he were on poor pastures and only poor pastures (lots of fat can be deposited in the testicles of bulls on a high-starch diet.

And, yes, a big scrotal on a big bull is quite a different circumference than a big scrotal on a smaller bull.

My preference is to see contemporary bull calves ranked in a few ways:

1) Current weight as a % of projected mature weight (this is calculated by taking the current hip height, and using standard frame score charts, to project to a mature frame score (and therefore a projected mature weight) for each bull calf, and then calculating the percentage of their mature weight they currently have (current weight / projected mature weight) --- the higher the percentage, the faster the maturing)

2) Current scrotal measurement as a % of projected mature weight.

The best bull in any given group should be at/towards the top of both lists. IMO, any bull below the half-way mark of either list should be steered; the ones that barely make it should be sold for only a little bit above commodity prices.

 

[Boot Jack Bulls]

As said, actual individual performance is useful. NALF suggests all Limi breeding bulls measure at least 32 cm at 1 year. We shoot for a 38, and those that are not under 34 don't keep them for long. Our semen tech actually recommends 38 as the target for the Limis, but suggests anything over 42 or so may be too big for that age.

I meant those that are under 34 don't keep them for long. Just noticed the error and I can't edit my original post???

 

[Supa Dexta]

Can only edit briefly and then its set in stone around here.

 

[Lucky_P]

The relationship between yearling SC and age of daughters' puberty is way overplayed...

"The most often quoted data relating scrotal circumference of the bull and reproductive traits of his daughters indicates that for each centimeter larger a bull's scrotal circumference:
his daughters may reach puberty 0.8 days earlier
his daughters are more likely to calve for the first time 0.8 days earlier
his daughters' calf weaning weights are likely to be 0.75 lb. heavier
Hence, while the genetic relationship between scrotal circumference and age at puberty is "real", the impact of selecting for scrotal circumference on when a bull's daughters are bred and calve or on their potential lifetime productivity is small."

More good stuff on SC here: http://www.kakahuangus.com/news/the-scr ... bandwagon/

 

[WalnutCrest]

The relationship between yearling SC and age of daughters' puberty is way overplayed...

"The most often quoted data relating scrotal circumference of the bull and reproductive traits of his daughters indicates that for each centimeter larger a bull's scrotal circumference:
his daughters may reach puberty 0.8 days earlier
his daughters are more likely to calve for the first time 0.8 days earlier
his daughters' calf weaning weights are likely to be 0.75 lb. heavier
Hence, while the genetic relationship between scrotal circumference and age at puberty is "real", the impact of selecting for scrotal circumference on when a bull's daughters are bred and calve or on their potential lifetime productivity is small."

More good stuff on SC here: http://www.kakahuangus.com/news/the-scr ... bandwagon/

So, with those averages, you realize there are those who improve more and those who improve less than those averages...right?

This is why, if you keep homegrown bulls or buy bulls from someone else, you should prefer bulls who are out of cows who calved their first calf younger than the vast majority of their contemporaries and who had a faster breed-back than the vast majority of their contemporaries ... rinse and repeat. So, if a heifer calves a week earlier than her contemporaries and breeds back ten days earlier ends up, at some point in her life, giving me a nice meaty bull (who is also at the top of his contemporary group in terms of "current weight as a % of projected mature weight" and "scrotal as a % of projected mature weight" ranks like I mentioned above), that bull would be a wonderful candidate for some real heard fertility improvement.

You should only look to keep/buy bulls out of cows who bred up early in their lives AND who bred back quickly...and who calved w/o assistance...and who did so with a good attitude.

 

[Nesikep]

That brings up another good question... At what age do you require your heifers to be cycling? Is it really desirable to have heifers cycling at 6 months?... as long as the vast majority (95-100%) are cycling by a 14 months are you gaining anything by having a significant portion of them possibly being bred too early? Do all heifers who start cycling later (12 months) have problems breeding back?

The mother of the bull calves I've kept has been a good cow, at the time we were breeding at 26 months (gave up on that after a couple years), but has always maintained good condition while raising exceptional calves, and nearly always bred back on the first cycle (once out of 8 she was early in the 2nd cycle).

I think more important that selecting for SC, is to select for the traits you want directly... Cull what doesn't make a good calf and the rest will start to take care of itself.

LuckyP, very good link!

 

[allisonr]

Thanks everyone for your responses! Didn't mean to stir up so much commotion! :lol:

wbvs58- I misspoke when I said EPD. I guess I just meant the data provided about the bull such as BW, WW, YW, SC etc. To get a full picture of what I'm talking about, Select Sires has an "EPD Spreadsheet" for each breed and each bull within that breed respectively (link below). As this spreadsheet doesn't blatantly say the SC in cm, but rather 0.56 +/- for example, I was curious as to how to tell a "good one" from the crowd. I did some research on how to analyze EPD spreadsheets (I guess that was my underlying problem, opps) and have a better idea now.

http://www.selectsiresbeef.com/inde...arch_strait&breed=Angus&sort=ASC&sortf=bw epd

 

[allisonr]

Also, thanks for the sharing the link, Lucky, interesting read!

 

[Nesikep]

My take on it according to the link LuckyP posted would be that as far as using any of those bulls for replacement heifers, it really wouldn't make much of a difference, they wouldn't be listed as bulls if they didn't pass the BSE.. if bulls you raise have too small a SC to pass a BSE, then it would become relevant.

 

[Supa Dexta]

I've had a yearling bull measure well over 32. Problem was he only had one -big- nut. Measurement don't mean much to me as long as they're both there, and 'big enough'.

Slaughtered that bull and he only did have one.

 

[Lucky_P]

Larger SC in yearling animals does have some importance - it's indicative of a 'bigger factory' for production of spermatozoa - and greater capacity for that bull to be able to settle more females.

That said, IMO, much of the attention paid to higher/larger SC, with regard to earlier puberty in daughters of a given bull... is overplayed. For every 1cm larger SC a yearling bull has, his daughters reach puberty 0.75 days earlier...
So what... a heifer sired by a bull with 34cm SC comes into heat about 4 days earlier than one sired by a bull with 28cm SC(I'm just making up numbers, here.)
I don't WANT heifers cycling before 6 months of age... If they're cycling regularly by 14 months... that's plenty early for my purposes.

Have had a couple this year, that were cycling by 5-6 mos; not a desirable situation here... if I'd not actually seen them standing, I wouldn't have known to watch for return to heat(or Lutalysing them) to ensure that they didn't get bred by the one bull calf in their group that had been retained intact for use as a cleanup bull... and might have been surprised with a heifer delivering out-of-synch with the herd... at 14 months of age.

 

[Supa Dexta]

I just have to lute my larger heifers at weaning, because I always have a handful bred now by 5-6mo. Its a hassle, but has become part of the weaning routine now it seems.

 

[Lucky_P]

SD,
We used to have an occasional 'teenage pregnancy' back in the day before we were really doing any management... bull ran with the cows year-round, often didn't get around to castrating bull calves etc.

But, since we actually started 'managing' - about 10 years ago... and went to Angus sires about that time, as well... I've had a hard time getting heifers to cycle in time to breed at 15 months. Have had a few Simmental-sired and Shorthorn sired heifers the last year or two that have been cycling around weaning time... but that's definitely not been a concern for anything with a whole lot of Angus in 'em...

 

[Supa Dexta]

ha. That makes it sound like I'm not managing things. Bulls go out in June, stay out til around now, then they're in the barn for winter. Calves came off in september at around 6mo age. If for some reason something doesn't get bred in time, atleast she's late bred to sell since the bulls are there to catch em. I've thought of pulling them, but its a pain when I started feeding in Oct, if they're all in a group its just dump and go.

What about the range herds. I assume they toss their bulls out in spring and gather in fall as well. But perhaps being mainly angus its less of a problem for them.

I'd much rather deal with a few lute shots at weaning, than worry about if they're gonna breed by 15mo.

 

[Bigfoot]

It's been my experience that eared females sexually mature a little later. I'm selling a few heifers next week, (gonna take a beating on them to) because they bred late.