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It has come to the attention of the IMZA Board of Directors, that some of the short stocky Miniature Zebu animals that many of us love, may carry a dwarfism gene. This gene may have been a part of Miniature Zebu cattle since they were first imported.  Previous DNA dwarfism tests did not allow this gene to be identified.


The IMZA's Science and Technology Committee has been working diligently with the University of California Davis, Veterinary Genetics Laboratory (VGL) to assist in the development of a test to identify this newly discovered gene, now called BDz. We are now able to announce that after a significant testing period, a test for the dwarfism gene found specifically in Miniature Zebu, is available.


Although the existence of this newly discovered dwarfism gene (BDz) is not good news, it also is not a catastrophic event which should panic Miniature Zebu owners. Animals that carry this gene are typically normal, although they may be shorter and more compact.  With knowledge and careful management practices, these cattle can continue to be a valuable part of the Miniature Zebu Cattle industry.  With the availability of this new testing, you are now able to make better breeding decisions.


This newly identified form of dwarfism, (BDz) is similar to the BD1 dwarfism which has existed in Dexter Cattle for hundreds of years. According to VGL, BD1 has also been found in a few Miniature Zebu Cattle. BD1 testing is a different process and will not detect the BDz gene. Because the 2 forms of dwarfism may possibly occur in Miniature Zebu Cattle, it is recommended that breeding animals be tested for both, BD1 and BDz. Carriers of either form, or a combination thereof, are subject to the same risk. As a result of our efforts, a simple combination panel test for BD1 and BDz, using tail hair pulled from your animals, is now available through UC Davis VGL. 


Most of the possible negative repercussions of this gene occur only when two animals carrying this gene are mated together.  Please refer to the Probability Statistics for Breeding Miniature Zebu Cattle below to further explain the risk factors involved.


----- Probability Statistics for Breeding Miniature Zebu Cattle-----

Non-carrier bred to a non-carrier = 100% chance of a non-carrier offspring
Non-carrier bred to a carrier = 50% chance of a carrier offspring and a 50% chance of a non-carrier offspring

Carrier animal bred to a carrier animal = 25% chance of a non-carrier offspring, 50% chance of an offspring which will carry the BDz gene, & a 25% of a dead bulldog dwarf calf.


With the availability of this new testing, you will now be able to make better breeding decisions. Through our continuing efforts, our herd book and record keeping, the IMZA will be able to educate, help you manage and allow you to make responsible breeding choices. The IMZA's foremost concern is to preserve the breed and to serve our members. Through new technology and research, we will continue to do so.



IMZA Board of Directors


If you would like to test your Miniature Zebu and need assistance please contact:

You can read more about BDz here:

How to submit an IMZA registered Miniature Zebu for testing:   see below

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