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Scrotal Circumference: Difference between revisions

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[[Category: Reproduction Traits]]
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Scrotal circumference for yearling bulls is collected between 320 and 440 days of age. Scrotal circumference is measured using a scrotal tape around the widest part of the scrotum when the testicles are fully extended. The tape should be pulled firmly around the scrotum. It is recommended to record the measure a few times to ensure accurate results. The circumference of the scrotum is recorded in centimeters.
===Phenotype===
Scrotal circumference is collected between 320 to 440 days of age. Scrotal circumference is measured using a scrotal tape around the widest part of the scrotum when the testicles are fully extended. The tape should be pulled firmly around the scrotum. It is recommended to record the measure a few times to ensure accurate results. The circumference of the scrotum is recorded in centimeters. Describe ways the phenotype is collected
      
      
===Adjusted Value===
===Adjusted Value===
The Beef Improvement Federation recommends age adjustment factors specific to breed for bulls less than 12 months old. The recommendations are presented in the table below. The age adjustment factor should be used in the following equation:  
The Beef Improvement Federation recommends age adjustment factors specific to breed for bulls less than 12 months old<ref name="Geske et al., 1995 "> Geske, J. M., R. R. Schalles, and K. O. Zoellner. 1995. Yearling scrotal circumference prediction equation and age adjustment factors for various breeds of beef bulls. Ag. Exp. Sta., Kansas State Univ. Rep. of Progress 727:99.</ref>. The recommendations are presented in the table below. The age adjustment factor should be used in the following equation:  


365-day SC=actual SC + [(365-age in days) x breed specific age adjustment factor]
365-day Srotal Circumference = actual Scrotal Circumference + [(365 - age in days) x breed specific age adjustment factor]
 
{| class="wikitable" style="margin: auto;"
!colspan="6"|Age Adjustment Factors for Scrotal Circumference
|-
|Breed
|Adjustment
|-
|Angus
|0.0374
|-
|Charolais
|0.0505
|-
|Gelbvieh
|0.0505
|-
|Hereford
|0.0425
|-
|Limousin
|0.0590
|-
|Red Angus
|0.0324
|-
|Simmental
|0.0543
|}


  Table
Most breed associations record scrotal circumference and therefore have developed their own age adjustment factors for scrotal circumference. Certain associations also have an age of dam adjustment factor for yearling scrotal circumference. It is recommended to use the breed association adjustments when possible in order to increase the accuracy of the adjusted measure.  
Most breed associations record scrotal circumference and therefore have developed their own age adjustment factors based on data they have collected. Certain associations also have an age of dam adjustment factor for yearling scrotal circumference. It is recommended to use the breed association adjustments when possible in order to increase the accuracy of the adjusted measure.  


===Contempory Group===
===Contemporary Group===
<!-- Discuss how contemporary groups are formed -->
Scrotal circumference is generally measured with other yearling bull measurements including weight and height, so use of the same contemporary grouping strategies as those for yearling bulls would apply.


===Genetic Evaluation===
===Genetic Evaluation===
<!--
Scrotal circumference should be run in a multiple-trait model with a regularly recorded trait such as yearling weight.  
    Discuss the genetic model for EPD production. 
    E.g., direct, maternal, permanent environment due to dam.  
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===Usage===
===Usage===
Scrotal circumference is measured to estimate the potential number of sperm cells that could be produced. It has been shown bulls with larger scrotal circumference reached puberty and produced higher quality sperm at a younger age. Furthermore, larger scrotal circumference has been associated with an increased percentage of progressively motile sperm and less abnormal sperm production (Christmas et al., 2001; Garmyn et al., 2007).  
Scrotal circumference is measured due to its positive relationship with the potential number of sperm cells that the bull can produce. It has been shown bulls with larger scrotal circumference reached puberty and produced higher quality sperm at a younger age and that their daughters also reached puberty at a younger age. Furthermore, larger scrotal circumference has been associated with an increased percentage of progressively motile sperm and less abnormal sperm production <ref name="Christmas et al., 2001"> Christmas R. A., D.W. Moser, M.F. Spire, J.M. Sargeant, and S.K. Tucker. Genetic relationships among breeding soundness traits in yearling bulls. In: Cattlemen’s Day. 2001. Manhattan, KS. Pp. 1-3.</ref><ref name="Garmyn et al., 2007"> Garmyn, A.J., D. W. Moser, R.A Christmas, J.M. Bormann. 2011. Estimate of genetic parameters and effects of cytoplasmic line on scrotal circumference and semen quality traits in Angus bulls. J. Anim. Sci. 89: 693-698.</ref>.  
   
   
Moreover, it has become increasingly popular for beef producers to market yearling bulls, which generally have not reached sexual maturity. Studies have shown bulls less than 15 months of age were more likely to be classified as deferred when evaluated for a BSE. Scrotal circumference can provide a more accurate predictor of onset of puberty when compared to other measurements such as height or weight (Carson 1997). Due to the relationship between scrotal circumference and these economically relevant traits, producers may wish to utilize scrotal circumference as a culling factor and place selection emphasis on scrotal circumference EPDs if selling bulls.
Yearling bulls offered for sale would usually have a Breeding Soundness Exam that would include scrotal circumference. Scrotal circumference can provide a more accurate predictor of onset of puberty when compared to other measurements such as height or weight<ref name="Carson and Wenzel 1997"> Carson, R.L. and J.G. Wenzel. 1997. Observations using the new bull-breeding soundness evaluation forms in adult and young bulls. Vet Clinics of North America: Food Animal Practice. 13:305-311.</ref>. Due to the relationship between scrotal circumference and measures of reproductive performance, producers may wish to utilize scrotal circumference as a culling factor and place selection emphasis on scrotal circumference EPD.
 
==References==

Latest revision as of 13:48, 13 April 2021

Scrotal circumference for yearling bulls is collected between 320 and 440 days of age. Scrotal circumference is measured using a scrotal tape around the widest part of the scrotum when the testicles are fully extended. The tape should be pulled firmly around the scrotum. It is recommended to record the measure a few times to ensure accurate results. The circumference of the scrotum is recorded in centimeters.

Adjusted Value

The Beef Improvement Federation recommends age adjustment factors specific to breed for bulls less than 12 months old[1]. The recommendations are presented in the table below. The age adjustment factor should be used in the following equation:

365-day Srotal Circumference = actual Scrotal Circumference + [(365 - age in days) x breed specific age adjustment factor]

Age Adjustment Factors for Scrotal Circumference
Breed Adjustment
Angus 0.0374
Charolais 0.0505
Gelbvieh 0.0505
Hereford 0.0425
Limousin 0.0590
Red Angus 0.0324
Simmental 0.0543

Most breed associations record scrotal circumference and therefore have developed their own age adjustment factors for scrotal circumference. Certain associations also have an age of dam adjustment factor for yearling scrotal circumference. It is recommended to use the breed association adjustments when possible in order to increase the accuracy of the adjusted measure.

Contemporary Group

Scrotal circumference is generally measured with other yearling bull measurements including weight and height, so use of the same contemporary grouping strategies as those for yearling bulls would apply.

Genetic Evaluation

Scrotal circumference should be run in a multiple-trait model with a regularly recorded trait such as yearling weight.

Usage

Scrotal circumference is measured due to its positive relationship with the potential number of sperm cells that the bull can produce. It has been shown bulls with larger scrotal circumference reached puberty and produced higher quality sperm at a younger age and that their daughters also reached puberty at a younger age. Furthermore, larger scrotal circumference has been associated with an increased percentage of progressively motile sperm and less abnormal sperm production [2][3].

Yearling bulls offered for sale would usually have a Breeding Soundness Exam that would include scrotal circumference. Scrotal circumference can provide a more accurate predictor of onset of puberty when compared to other measurements such as height or weight[4]. Due to the relationship between scrotal circumference and measures of reproductive performance, producers may wish to utilize scrotal circumference as a culling factor and place selection emphasis on scrotal circumference EPD.

References

  1. Geske, J. M., R. R. Schalles, and K. O. Zoellner. 1995. Yearling scrotal circumference prediction equation and age adjustment factors for various breeds of beef bulls. Ag. Exp. Sta., Kansas State Univ. Rep. of Progress 727:99.
  2. Christmas R. A., D.W. Moser, M.F. Spire, J.M. Sargeant, and S.K. Tucker. Genetic relationships among breeding soundness traits in yearling bulls. In: Cattlemen’s Day. 2001. Manhattan, KS. Pp. 1-3.
  3. Garmyn, A.J., D. W. Moser, R.A Christmas, J.M. Bormann. 2011. Estimate of genetic parameters and effects of cytoplasmic line on scrotal circumference and semen quality traits in Angus bulls. J. Anim. Sci. 89: 693-698.
  4. Carson, R.L. and J.G. Wenzel. 1997. Observations using the new bull-breeding soundness evaluation forms in adult and young bulls. Vet Clinics of North America: Food Animal Practice. 13:305-311.