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Posted: Tue May 19, 2009 10:43 am
by Louisa Gidney
I've just come across an interesting paper relating size of bulls' testicles to fertility, and fertility in their daughters. There is a helpful chart of average size for commercial breeds. On a purely visual level, the average Dexter appears to be as well endowed as the larger breeds. So, the big question is, has anyone ever measured the circumference of their bull's attributes! I tried last night with Leo but he was not co-operative. If anyone would be prepared to have a go & post the measurements, I'd be interested to see how the results compare. Ball park figure for commercials is in the region of 30cm/12".
Posted: Tue May 19, 2009 11:00 am
by Broomcroft
My main bull is penned near the crush at the moment, so I'll have a go but it'll be later in the week!
Thanks for the "Ball park figure" Louisa :D. I assume that you (a) measure at the widest point, and (b) you measure both at once? Looking at a tape rule 12" for the two looks small but we'll see.
Edited By Broomcroft on 1242727454
Posted: Tue May 19, 2009 1:16 pm
by Louisa Gidney
Thanks Broomcroft, here's the info:
Scrotal Circumference
Measuring the scrotal circumference of young bulls is an accurate, repeatable method to assess current and future sperm-producing ability. The measurement gives an estimate of the weight of the testes, which is directly related to the level of sperm production. Scrotal measurement is also positively correlated with semen volume and quality. Table 2 contains minimum recommended scrotal measurements by breed and age. Bulls with adequate scrotal development for their age have a higher probability of becoming satisfactory breeders than bulls with smaller scrotal circumferences.
Scrotal circumference is of medium to high heritability. Fertility of the male offspring can be increased by selection for this trait. The scrotal circumference of a bull is also positively related to the fertility of his daughters. Heifers from sires with larger than average scrotal circumference tend to reach puberty earlier than those from bulls with smaller scrotal circumferences. Increased scrotal circumference in sires is also favourably correlated to their daughter’s age at first breeding, pregnancy rate and days to rebreeding after calving. Due to low heritability, direct selection for female fertility traits has not been successful. The strong genetic relationship between scrotal circumference and female reproductive traits provides an alternative selection method.
Posted: Thu May 21, 2009 12:34 pm
by natmadaboutdexters
I'm sorry but I now have visions of Dexter owners all over the country rushing outside with a tape measure and acosting their bulls! My bull is a gentle sort so I suppose I should give measuring a try for research purposes!
Natasha :D
Posted: Thu May 21, 2009 12:58 pm
by Duncan MacIntyre
special measuring devices can be got for the purpose, with a loop measuring the circumference on the end of a stick, presumably safer than getting down there with a measuring tape. As far as I remember the Elite Bull inspectors report has an entry for this measurement, maybe DCS could supply Louisa with anonymous data?
Duncan
Posted: Thu May 21, 2009 3:09 pm
by Louisa Gidney
Right. I'll try DCS but the last time I requested data (a section on the yellow birth notification card) I was passed from pillar to post & finally told there were no records!
It's a bit cold up here at the moment, the measurement isn't accurate if the testes are close to the body & the scrotum wrinkled.
Needless to say my supervisor is in hysterics at this whole idea.
Nevertheless a link between size and fertility has been demonstrated in large breeds, also size and the onset of fertility in the young bull. Visually I think my Dexters look as well endowed as commercial bulls but I need some data to prove this. I would like to suggest that one reason why small cattle were preferred in the past was that fertility levels were good, compared to the "improved" C19th Shorthorns, were one top bull only sired 12 calves.
Posted: Mon May 25, 2009 10:05 am
by Louisa Gidney
Well, I grovelled round the nether regions of my two bulls at the weekend. Not wholly accurate measurements but both are about 34cm, which compares to recommended size for Limousin & Blonde d'Aquitaine of 34cm, Hereford & Shorthorn 35cm, Angus & Charolais 36cm & Simmental 37cm.
So my contention that, for body size, the Dexter is well endowed would appear to be reasonable. This would also explain all the precocious youngstock with teenage pregnancies.
Posted: Mon May 25, 2009 2:27 pm
by Rebecca
Hi Louisa , sorry - meant to reply to this earlier. Here in Australia Scrotal circumference is included in the inspection of the bulls that are on our AI register. If you go to the Dexter Australia Website: http://dexter.une.edu.au/
Under member services (you don't need a login) you go to "Animal Enquiry" then go to "Semen Catalogues" and "Accredited Sires". Or you can try this for the direct link to that page:
http://abri.une.edu.au/online....C2B3C3A
You can then select the bull you want and look at his details. From memory most include a Scrotal Circumference. These are not just Australian Bulls, infact most of them are overseas sires. Hope this helps with your stats. 
Edited By Rebecca on 1243258099
Posted: Mon May 25, 2009 3:12 pm
by Broomcroft
That's a great system Rebecca. Really thorough. Well done to Oz.
Posted: Mon May 25, 2009 6:04 pm
by Broomcroft
All my Dexter bulls are a lot sexier than my Angus. I reckon a Dexter could handle twice as many cows. Apart from anything else, they don't have to spend so much time filling their frame and they have more energy. I have 4 dexter bulls, all non-chondro, and as they go down in size, the sexier they are. You never turn your back on the smallest one :D. I am hoping to measure one bull tomorrow but even if I can't manage it, you can easily see that their bits and bobs are much bigger compared to their frame than the Angus.
Posted: Tue May 26, 2009 10:10 am
by Louisa Gidney
Rebecca & Broomcroft, many thanks. I may quote Broomcrodt as a pers. comm.
I have found, on the web, stats for 6 yearling bulls in S. Africa. Google is a most amazing invention, I keep getting side tracked by all sorts of things.
For example cow wrestling in Italy & Switzerland, search for combat des reines; amazing floral head wear on cows returning from alpine pastures, search for Alpabzug or Almabtrieb; another breed like a Dexter with red calves turning black/brown as adults, search for Herens
etc, etc!
Posted: Tue May 26, 2009 10:22 am
by Louisa Gidney
WOW, the Aus figures are amazing - lots of bulls 37+cm, better endowed than Simmentals!
Posted: Tue May 26, 2009 5:30 pm
by Broomcroft
Not wishing to take anything away from the Oz bulls' prowess in their moment of glory, but I do wonder whether the warmer climate affects size?
Posted: Tue May 26, 2009 6:06 pm
by Broomcroft
I have just measured my stock bulls testicles at the point of largest circumference which I assume is the correct place? The first time I measured with gentle pressure, but not loose, and they were 43 cm. The 2nd time I put a little more pressure on the tape (at which point he kicked me), and that came out at 42 cm.
He is the bull in my avatar and he is slightly over breed standard now at age 8.
So somewhere between 42-43 cm.
(PS. I have a witness!)
Edited By Broomcroft on 1243357676
Posted: Wed May 27, 2009 9:38 am
by Louisa Gidney
Thanks, Broomcroft. I think you answered your own question there as I have a sneaky feeling that, even in May, the Welsh Border region might be a tad cooler than Oz.