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Monitoring Genetic Defects

 

DNA marker tests provide new tools to more efficiently identify and monitor genetic defects.  The American Simmental Association`s Genetic Abnormality Policy is a scientifically based approach to managing and ultimately reducing the incidence of genetic abnormalities in our herds.  It leverages cutting-edge technology both from DNA testing and software development standpoint to identify and present information on the potential for an animal to carry genetic abnormalities.

 

 

Policy:

Sires and donor dams that fall into ASA’s carrier in lineage (CL) or risk population categories (PR) must be tested before registration certificates and EPDs are available on new progeny.  If DNA is not available on a sire or donor dam in question, their progeny must be tested before registration certificates and EPDs are released.  No testing is required on dams of natural calves.

 

The results of the test do not impact eligibility for registration of the an animal or its calves.  The test requirement goes into effect when a DNA marker test becomes commericially available and the defect has been named by the Board of Trustees as a defect to be monitored.

 

Solutions Available to Meet Testing Requirements:

1.  Provide test result documentation from a lab, breed association or ASA approved source.

2.  If sire and/or donor dam has not been tested, complete required genetic testing.

3.  If sire and/or donor dam is not available for testing, complete required genetic testing on offspring.

 

The genetic defects for which DNA marker tests are available AND on which ASA is monitoring are listed in the table below in red.
Code Name DNA Marker Test Testing Required

Risk

Population

AL Albinism

not yet

   
AM Arthrogryposis Multiplex (curly calf) Yes Yes

Angus

DW1 Dwarfism (Angus) Yes    
CA Contractual Arachnodactyly  (Fawn Calf Syndrome) Yes Yes Angus
DD Developmental Duplication Yes Yes  
NH Neuropathic Hydrocephalus (hydro, water head) Yes
Yes Angus
HT Hypotrichosis (hairless) not yet    
IE Ideopathic Epilepsy not yet    
OS Osteopetrosis (marble bone) Yes Yes  
PHA Pulmonary Hypoplasia with Anasarca Yes Yes MA,CA,SS
PR Protoporphyria (photosensitivity)  not yet    
TH Tibial Hemimelia Yes Yes MA,CA,SS

 

ASA`s TraitTrac System: genetic defect monitoring made easy

 

ASA`s coding system shows every animal`s current genetic defect status.  As information new information is added to ASA`s records the TraitTrac system autuomatically update the genetic status of an animal and its descendants. 


TraitTrac  codes use to designate Genetic status of each defect
Code Description Testing Requirement

TF

Tested Free

Tested Free of the genetic defect

none

PF

Pedigree Free

Pedigree Free (not tested).  All ancestors in question tested free (TF) of defect.  none

DF

Documented Free

Documented Free (not tested). Documented Free from another breed association or authorized source.  none

AF

Assumed Free

Assumed Free (not tested). No known carrier in lineage and less than 1/8 blood from a population with a significant incidence of the defect.  none

PR

Population  Risk

Population Risk (not tested). Has at least 1/8 blood from ancestors from a population with a significant incidence of the defect. Sires and donor cows must be tested before (additional) calves can be reported

CL

Carrier in Lineage

Carrier in Lineage (not tested). Has a carrier in pedigree without intermediary ancestor(s) Tested Free (TF). Sires and donor cows must be tested before (additional) calves can be reported

TC

Tested Carrier

Tested Carrier of the genetic defect none

 

The genetic defect status for any animal can be viewed from the epd/pedigree display from Animal Search under Data Search.  In addition, herd summaries with genetic defect status are available from Reports under Herd Mgmt.  Keep in mind the only animals guaranteed to be free of an abnormality are those Tested Free (TF) category.  For example, since animals  coded as Assumed Free (AF) have not been tested there may by some risk they are carriers of a genetic defect. Also keep in mind that for untested animals the coding system relies on the accuracy of pedigree records.


Please note: Some foundation registered animals that are registered in another breed association are coded as PR  when more information from the originating breed association would show the animal is not from any effected lines of cattle.  These animals can be updated to a Documented Free (DF) status by getting acceptable documentation from the breed association. 

  

For more information about genetic defects see these links:

Genetic defects, ASA information page

   Congenital Defects in Cattle , Beef Cattle Handbook, Extension Beef Cattle Resource Committee.
  "Cowboy Genetics" - Written by Dr. Lana Kaiser and originally published in the 2006 May/June edition of the Maine-Anjou Voice
   Frequently Asked Questions