Author: Carlos Martín Acuña MV
Scrotal Circumference (EC) was incorporated in the routine examination of a bull in the 70s, before sale to 20-22 months pre-service or in adult bulls.
Since then much water has passed under the bridge and numerous papers have been published on the subject.
Foote mainly foreign authors and Coulter, have dedicated many works about it and today Dr. Coulter has deepened the study of the testes with the use of a thermograph, certainly high tech, inaccessible to a veterinarian of private activity.
By our experience having measured testicles for 40 years and then to have worked with Dr. Mike Blockey in Australia believe that the hands and mind and the use of a escrotímetro are the best weapon we now have to evaluate testes of a bull for use in natural service (NS) in the field.
We know that every gram of testicular parenchyma produces 10-20 million sperm per day and that the correlation factor (r.) between testicular weight and the EC is 0.98, therefore the measurement of C.E. is highly predictive of the amount of sperm testes produce these per day. A bull whose his C.E. is 35 cm. have testes that weigh about 460 grams. The 87% is testicular parenchyma, or 400 grams. If we multiply the 15 million sperm are produced daily for 1 gram of testicular parenchyma, the 400 grams produce 6,000 million
Sperm daily. Do you think you can finish a bull semen in SN to field?
Also with the tip of our fingers can feel the consistency or testicular tone (TT) and this is highly correlated with semen quality that will produce these testes.
For these reasons we think that measuring the EC and feeling the T.T. the testicles of a bull can be predicted with a high degree of accuracy the quantity and quality of semen of this bull for SN the field.
I think personally check semen during checkup before service or sale as a technique impractical to do it. Therefore implement not justified.
A study conducted and published in Engormix with the title:
“Evaluation of breeding bulls in rodeos: Is it necessary to examine semen? Avala our thinking about it.
When I started my career in 1973, some colleagues performed a routine semen analysis in the checkup of bulls and bulls believe that many have been unfairly for slaughter by an observation of his semen.
Today with the advancement of technology in the market very sophisticated electroeyaculadores facilitate good ejaculate being more accurate diagnosis.
Anyway has no practical sense to analyze 100 samples of semen, because if we do just in those bulls with grade 3/3 TT (Soft) would analyze only one or two bulls over 100 reviewed.
In conclusion bulls with C.E. to exceed 32/34 cm. and T.T. 1/1 (very strong) or 2/2 (firm) are fit for SN the field.
According to Dr. Albert Barth of the University of Saskatchewan in Canada is due to sperm morphology and not suffice with taking a sample and observe motility and concentration.
We have never taken the exam semen by electroejaculation in bulls during the checkup and the results obtained in pregnancy rates taking controlled diet and health suggests that we are not justified in semen analysis routine checkup. Especially when from 1985 to date, we have reduced the percentage of bulls used at 2% with extreme values between 1.5% and 2.5% and excellent pregnancy rates.
A compilation I made with tests performed by several colleagues, between 1986 and 1992, they used bulls CS High and Very High 148,300 cows met in S. N. to field in 51 establishments of 7 provinces of Argentina, in services that ranged from 60 to 110 days and with a percentage of bulls between 1.7% and 2.4%, with very good food and health controlled, obtained for 94% of pregnancy to the touch. The 3,000 bulls used were physically fit, with good EC and T.T., but NOT had his semen analyzed.
These data are the commented Dr. Barth after his lecture at the Third International Symposium on Animal Reproduction in June 1999 in Villa Carlos Paz (Province of Cordoba). His subject was the evaluation of bulls and was wondering is it necessary to take a sample of semen? In Canada, the reality is different, more than 50% of the breeding herds have about 50 cows and often reaches temperature – 30 ° C, even with the snow freezing the scrotum. So our reality in Argentina is quite another.
In 1992 I had a chance to take a course with Dr. Coulter also Canadian and to my question: what percentage of bulls fertility depress me a rolled down the pregnancy rate in SN a field if not included semen analysis in the pre-service checkup? Your response 15 to 20% stunned me. Also amazement of colleagues present. Asked the same question Dr. Mike Blockey from Australia told me that it would not be more than 2% of bulls that we could escape after a manual checkup right testis measuring its CE and feeling his TT, and then have alterations in their semen that we procreate rate decrease in breeding herd.
I consider measuring C.E. a fundamental part in the examination of a bull, but I do not share for anything bigger is better, because that way we will fall once again in a race for the size.
Today I observe a school of thought that the bulls High or Very High CS they are going to end and leave semen without impregnate many cows in the field for that reason.
Nothing is further from the truth and I very convenient transcribing Dr. Mike Blockey concepts about it.
He worked with different bulls C.E. and measured Conception Index (CI) which is the pregnancy rate in the first 21 days of service (1st heat).
In the 3 experiments bulls used Very High CS, 7 or more services in the test pen 20 minutes. In the first experiment observed nine bulls made an average of 80 services each in a period of 16 days. This is 5 services a day. In the four days following each of the nine bulls served 25 cows (1 serving per cow) with a service system controlled by hand. Seven weeks after rectal examination performed to determine the IC each bull could after they were “taken” 80 services.
Have they sold these bulls semen after 100 services? Not if his balls were big enough. Those whose testes measuring 30 cm or more obtained an IC of 65% which is what to expect when you allow bulls serve once the cows during estrus. Those whose testicles were between 26 and 29 cm., Obtained an IC 24%. His balls were not big enough and they ran out of semen.
The conclusion of this experiment was that the bulls of Very High CS must have a C.E. 30 cm. or more to enter service with 40 cows successfully.
In the second experiment, nine bulls entoró the equivalent of 60 cows each for a period of 21 days. 135 services each bull completed in 16 days, an average of 8.4 per day services. Then each hand bull gave service to 25 cows each for 5 days (1 serving per cow) to determine the IC who managed after having been “taken” 135 services. These bulls exhausted? Sperm reserves after giving 160 services? No, if your testes measured 32 cm. or more. These bulls attain an I.C. 72%.
Not obtained such I.C. if you are running out of semen.
Bulls with less than 32 cm. Semen were not enough and were I.C. 41% only.
The conclusion is that for bulls entorar Very High CS with 60 cows, each of these bulls testicles must be at least 32 cm. or more.
In the third experiment entoró eight bulls with the equivalent of 75 cows for a period of 21 days. Each bull served 200 times in 16 days, an average of 12.5 per day services. Then each hand bull gave service to 25 cows each during the five days following. Were these bulls impregnating a cow Very High CS after giving 225 services within 21 days? While his testicles measure both 34 cm. or more managed one C. I. 57%, which were between 30 and 32 cm. C. I. attain an of only 44%.
The conclusion is that to use Very High CS bulls with 80 cows each of the bulls must have testes that measured 34 cm. or more.
Three things were clear to him Mike Blockey:
First: the bulls either of Medium, High or Very High CS, distributed services that give in a very fair about the cows that are in heat that day. In other words, the bulls of Very High C. S. or any other bull, no favorites, spread their services in females in heat.
Second: the bulls Very High CS, serve each of the cows that are in heat two or three times. This gives them a C. I. zeal of 70-85%.
Third, while bulls Very High C. S. testes are large enough each cow can serve 2 or 3 times and produce enough sperm to keep getting an IC high week after week. This testicular size is what determines the number of cows with these sires Very High CS can entorar. That is, 30 cm. for 40 cows, 32 cm. for 60 cows and 34 cm. for 80 cows.
Now this is what happens with bulls of two years or more in Australia. I think the same happens in Argentina, says Mike Blockey, considering the following evidence:
150,000 cows in Argentina were entoradas a relationship bull: cow ranging from 1:40 to 1:100. Pregnancy rate after 10 to 12 weeks of service was 94%. These bulls are certainly not finished the semen.
Groups of bulls High C. S. with large enough testicles are entoraron with 50-70 cows each. Both in Australia and in Argentina these bulls achieved high pregnancy rates. They also ran out of semen.
Says Mike Blockey Summarizing their results as those obtained in Argentina with bulls of 2 and 3 years prove that bullfighting Very High CS achieve good I.C. even after having been “taken out” 80, 135 or 200 services in 16 days if your testicles are large enough.
Consider these experiments as Mike Blockey fundamental to understanding many things and clarify some misconceptions you have lying around in the minds of breeders and cabañeros, to follow U.S. and Canadian jobs, thinking they can be extrapolated to our bulls and systems breeding in Argentina.
I believe that the testicles of a bull are essential for reproductive future, taking into account not only the size but also the shape, consistency, position and size of the tails of the epididymis, etc..
We must remember that there is a biological plateau and above the 34 cm. of C.E. not achieve more impregnate cows.
If we refer to a sire for a campus and thus to produce bulls, one CE of 38 cm. or more may be appropriate because the heritability of it is moderate to high.
Other brilliant concepts to let us Mike Blockey on his last visit to Argentina in 1992 is referred to puberty.
A paper published by James Brinks on the correlation between EC and arrival at puberty of the daughters of these bulls, it asserts that for every inch of EC their daughters or female relatives with him, they would reach puberty 3 or 4 days before this in linear relationship. In the opinion of Mike Blockey what would happen and which Brinks did not notice in his work is that most EC bulls have crossed the barrier of 30 cm. first lower bulls C.E. It is known that the arrival of a bull puberty is when reaches 30 cm. of C.E. As you can produce an ejaculate 50 million sperm per cc. and with 10% or more of progressive motility, allowing it to impregnate a cow on SN the field.
So when Brinks. C.E. measured the bulls, the most C.E. daughters had cycled first, but according to Mike Blockey because it had been first the barrier of 30 cm., those with smaller testes had daughters who cycled later they had crossed the barrier of 30 cm. the older.
Puberty Index (I. P.)
Therefore it is very important that in the cabins begin to measure the EC from 8-9 months of age and to record the age and weight on each bull reached 30 cm. to learn which reached puberty at younger ages and lighter weights, this would predict that their daughters will be cycling at an early age and light weights.
The C.E. should be measured every month and divide the population into thirds to classify early puberty in bulls (PT), if you go through the 30 cm. at 8-10 months of age, puberty median (PM) if they do at 12-14 months of age and puberty distant (PL) at 15 months of age. At the same time measuring the C.E. using the balance would classify in light, medium and heavy. For this work is vital to have the date of birth.
I tried in this brief article, dump many concepts looking to clarify some controversial aspects, always remembering that the bulls with a CE 30, 32 and 34 cm. produce more sperm than you normally need to impregnate cows assigned to them in SN the field.
Then simply must identify bulls with less than 30 cm. and reject them. That is the way to ensure that we as suitable bulls have an IC satisfactory in rodeos.
Provided that nutrition and health are wholly owned.
Less than 2% of bulls with poor semen quality resulting in an IC less than 50%, despite having been classified as eligible in the checkup of the testicles.
The excellent semen quality bulls do not have IC than those with average semen quality. Nor would exceed those that are classified as questionable as classified Semen Dr. Albert Barth. We conducted several field trials comparing bulls with satisfactory sperm and questionable (as rated by Barth) in 2 100 herds and cows each IC of both herds was 73% with and 71% satisfactory sperm semen questionable.
These bulls were from Alta C. S. as the Alta bulls C. S. serve the cow in heat two, three or more times any issues with his semen would be offset by the amount of services received by a cow during rut.
Finally consider fundamental in the physical examination of a bull measuring EC and feel classifying the T.T.
All breeders must do so in efficient Torada with your veterinarian, before service and cabañeros should provide this information to customers.
That’s the best way to be efficient and achieve more than ever we need it.