Scrotal Circumference

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Oubuffel

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Hi Everybody!

The topic of scrotal circumference (SC) is one I've always found quite intriguing and honestly quite puzzling. In my younger years, grey bearded breeders used to share their vastly different opinions with me, regarding this matter. Some believed that an adult bull's SC should not measure less than 35cm, while others believed that smaller than 40cm is unacceptable. Some also believed that the bigger the better, while others said that over 50cm is much too large.

Plausibly, accurately measuring SC on any potential breeding bull, prior to buying or introducing him to cows, could save us both time and money, due to the fact that there's a good chance for a correlation to exist, not only between SC and fertility, but quite possibly also between SC and things like virility and prepotency.

So what I would like to ask all my Cattle Today friends, is to share the things they've personally experienced, related to SC. What would you say is too small, what's too big and why? Have you ever witnessed, know of or perhaps suspect any existing links between SC and things like fertility, virility, prepotency or anything else for that matter? You are very welcome to add any related information that could possibly contribute to this topic.

Looking forward to getting some very interesting feedback from you all!
 

simme

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How accurate is the measurement? I know of an instance of BSE exams 1 year apart on a mature bull. Same bull, same vet. Different by a couple cm. Smaller the last year. Does it change once mature? Did the vet just tighten the tape more?
 

snoopdog

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What we have experienced is it seems the heifers out of bulls with a larger SC mature earlier, but I have no proof. I don't believe it has any effect on fertility, or virility.
 

Buck Randall

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How accurate is the measurement? I know of an instance of BSE exams 1 year apart on a mature bull. Same bull, same vet. Different by a couple cm. Smaller the last year. Does it change once mature? Did the vet just tighten the tape more?
Both are possible. Illness or injury can cause them to get smaller. I've seen bulls lose a significant amount of scrotal circumference in a year (and lose fertility with it).

There definitely is some correlation with fertility and scrotal circumference, at least in the extremes.
 

FungusProudKY31

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What we have experienced is it seems the heifers out of bulls with a larger SC mature earlier, but I have no proof. I don't believe it has any effect on fertility, or virility.
I have never seen a proven study. But EXT was the major exception and widely used to improve "broken cattle" of that era.

In fed bulls, is it testicle or fat?

Are folks being honest?
 

SBMF 2015

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Hi Everybody!

The topic of scrotal circumference (SC) is one I've always found quite intriguing and honestly quite puzzling. In my younger years, grey bearded breeders used to share their vastly different opinions with me, regarding this matter. Some believed that an adult bull's SC should not measure less than 35cm, while others believed that smaller than 40cm is unacceptable. Some also believed that the bigger the better, while others said that over 50cm is much too large.

Plausibly, accurately measuring SC on any potential breeding bull, prior to buying or introducing him to cows, could save us both time and money, due to the fact that there's a good chance for a correlation to exist, not only between SC and fertility, but quite possibly also between SC and things like virility and prepotency.

So what I would like to ask all my Cattle Today friends, is to share the things they've personally experienced, related to SC. What would you say is too small, what's too big and why? Have you ever witnessed, know of or perhaps suspect any existing links between SC and things like fertility, virility, prepotency or anything else for that matter? You are very welcome to add any related information that could possibly contribute to this topic.

Looking forward to getting some very interesting feedback from you all!
Lots of good advice so far. SC is directly related to the amount of cows a bull can cover. A bull with a large SC and a high libido can settle a cow every 7 mins.

There is a correlation between SC and hfr fertility.

SC can be affected by body condition. Fat bulls usually measure a cm or 2 larger than bulls in working condition.

34cm for yearling bulls is passing. Mature bulls I like to see 42cm +
 
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Oubuffel

Oubuffel

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What we have experienced is it seems the heifers out of bulls with a larger SC mature earlier, but I have no proof. I don't believe it has any effect on fertility, or virility.
Thanks for sharing Snoopdog. I find what you're saying, very interesting and it's something I would personally be monitoring future. Hopefully someone else out there has perhaps witnessed something similar and would also be as kind as to mention it on this thread.
 
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Oubuffel

Oubuffel

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Lots of good advice so far. SC is directly related to the amount of cows a bull can cover. A bull with a large SC and a high libido can settle a cow every 7 mins.

There is a correlation between SC and hfr fertility.

SC can be affected by body condition. Fat bulls usually measure a cm or 2 larger than bulls in working condition.

34cm for yearling bulls is passing. Mature bulls I like to see 42cm +
Thanks for participating in the discussion regarding this topic, it's nice to hear from you again SBMF. Your observations are very interesting and completely in line with what I know out of my own experiences, as well the observations and experience shared by some of the other folks. You are the first person to provide us with actual SC sizes and for that I thank you. I would like to kindly as that you share your thoughts concerning the preferred maximum SC for a mature bull. 42cm + Sounds great, but how big is too big and why?
 

wbvs58

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In selling 2 yr old bulls I am much more comfortable with them over 40cm and not concerned with the occaisional 45 or 46cm. I'm not comfortable with any around the 35cm mark but have never had to replace any bulls in the 35-40cm range for lack of performance (fertility or libido).

Ken
 

SBMF 2015

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Thanks for participating in the discussion regarding this topic, it's nice to hear from you again SBMF. Your observations are very interesting and completely in line with what I know out of my own experiences, as well the observations and experience shared by some of the other folks. You are the first person to provide us with actual SC sizes and for that I thank you. I would like to kindly as that you share your thoughts concerning the preferred maximum SC for a mature bull. 42cm + Sounds great, but how big is too big and why?
I'm not sure there is a "To Big". As long as the bull and his testicles are healthy.
We have had bulls fail BSE's due to swollen, soft testicles.
As long as they don't hinder the bulls ability to move and perform I wouldn't worry about the higher side of the scale.
 

Dsth

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What we have experienced is it seems the heifers out of bulls with a larger SC mature earlier, but I have no proof. I don't believe it has any effect on fertility, or virility.
I use to wonder why the AI industry listed SC in the EPDs of the bulls. then I read an article about the direct relationship between SC and age of maturity in heifers. The larger the SC the earlier heifers mature. I have found that to be true. Used a below average SC bull and kept 2 heifers from him 3 years ago; neither heifer made it into the herd because they did not cycle until about 18-19 months. even after 2 attempts with 7 day CIDRs and PG.
 

okiek

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Here is my latest personal experience. I had a yearling bull last year. BSE was done within days of him being a year old. At that time his SC was 38. I put him on 5 heifers in late April which later calved in a 2 week period. I turned him in with 13 older cows in May. All but one of those calves in March. I've always heard the rule of 1 cow per month of age with a younger bull, but I think settling 18 head in a 60 day period was pretty good for a 14 month old bull. I attribute that to him having a fairly large yearling SC. I'm taking the same bull for his annual BSE today. I'll try to post his current SC but I suspect he will be over 42 based purely on what I have seen in growth.
 

Boot Jack Bulls

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If you don't believe SC has an impact on female fertility, look at the Limi breed in depth. When they were first imported, they were notorious for small SC and late maturity (among other issues, ie DOCILITY lol!). The biggest breeders in this country made a concerted effort to change this in the 90's and 00's. The generally adopted rule of thumb was that they sold no bull as a breeder with less than a 32" SC as a yearling. Again, this is a low number, but considering where they were before, this benchmark was a huge stride in the right direction. Now, Limis can stand shoulder to shoulder with other breeds in regards to SC and the females are now known for their early maturity.
 

FungusProudKY31

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Do a little searching in the AAA Sire search. Use min SC and max HP, max SC and min HP, ... and you will learn a lot. I still want to see the data on all of the extra good of a large SC bull. The only research I ever saw showed that daughters of large SC bulls were days earlier in cycling but not even a week. Never heard the 7 minute rule. Moderation is always hard to beat.
 

skangusguy

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Fwiw, my vet says he sees a lot of 40 cm plus yearlings that have subpar semen. Overfeeding between weaning and yearling can deposit fat in the scrotum which inflates the size but decreases fertility. He says best fertility is in the 35-40 range for yearlings.
 

CowsRcuddly

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Lots of good advice so far. SC is directly related to the amount of cows a bull can cover. A bull with a large SC and a high libido can settle a cow every 7 mins.

There is a correlation between SC and hfr fertility.

I believe 32 cm is passing on a yearling bull. Just saw one sell for good money at Woodhill with a 32 cm. He passed the "swimmers" test. Also, I was told by several old breeders that a bull with really large testicles runs the risk of freezing during really cold weather or getting too hot during the summer because he can't bring them up.
 
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SBMF 2015

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So what do you consider to large?
I think we used to test yearling bulls that measured 32cm, but more often than not they ended up on the "shows potential, retest in sixty days list"
Overly fat bulls defiantly have more trouble cooling down their testicles.
The environment that bulls winter in is more important than testicle size when it comes to freezing. Our bulls spend the winter on a deep pack mound of corn stalks. The composting stalks create heat. Steam raises when the bulls stand up in the winter.
I've also seen bulls freeze their nuts to a bare concrete floor.
 

Nkline

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I like to see normal shape/placement which includes seeing the tail of the epididymis. Usually if they look normal and you can see that, they will be towards the top of the normal range of size. Sheath angle matters a lot also, and rear legs.
 
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Oubuffel

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Here is my latest personal experience. I had a yearling bull last year. BSE was done within days of him being a year old. At that time his SC was 38. I put him on 5 heifers in late April which later calved in a 2 week period. I turned him in with 13 older cows in May. All but one of those calves in March. I've always heard the rule of 1 cow per month of age with a younger bull, but I think settling 18 head in a 60 day period was pretty good for a 14 month old bull. I attribute that to him having a fairly large yearling SC. I'm taking the same bull for his annual BSE today. I'll try to post his current SC but I suspect he will be over 42 based purely on what I have seen in growth.
Thanks okiek! Very interesting! Please give us an update as soon as you're back from the BSE. It will be very interesting to hear what his SC currently measures.
 
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