In this section of the website we feature ALL the articles written by HARTEBEESTLOOP BONSMARAS, mainly from our Bonsmara stud breeding program. In most of the articles we refer to what works for us at Hartebeestloop and how we do things in our Bonsmara stud. We also have articles done by other authors. If we can learn from you, we certainly will publish your work! This is a very comprehensive part of this website and we hope you enjoy reading and learning here!

CONTACT US: JOGGIE BRIEDENHANN +264 81 231 6169 (jbried@joggie.com.na)

Publication selected in the Archive of 2021:
March 2021


Hartebeestloop has a policy regarding handling and management of Double Muscling genes in our herd. It has become necessary to have this in place, as not only is this a very costly exercise, but let’s face it, it is also highly emotionally charged! “Rules” have made it easier for us to be consequent and stay on track to eventually remove this gene from our herd.

Your policy and the systems that you use may differ from ours. Management of double muscling genes will be herd specific and should be practiced as such.

This policy should be read and practiced in conjunction with the “Policy on the management of double muscling genes in COW selection – Part 2”.

Our policy on BULL Double Muscling management:

  1. Identify the bulls and cows in your herd that are carriers of the genes

  2. Go through the normal selection processes with their progeny
    • Select at wean through indices and structural correctness

    • Sell/cull the animals that do not meet minimum breed requirements at wean

    • Proceed as normal with those animals that meet minimum requirements

  3. Do another selection on the bulls pre-Phase D on structural correctness, functional efficiency and scrotum integrity. Cull the bulls with visible scrotum defects and also those that do not meet minimum breed requirements with regard to structural correctness and functional efficiency.

  4. Cull the bulls that do not meet minimum breed requirements at the end of Phase D testing. Not cost-effective to keep them, maintain them and then present them for stud selection.

  5. Cull the bulls that do not pass the annual stud selection.

  6. The bulls that passed the annual stud selection and that are sons of known carriers should be tested for the presence of the DM genes.
    • This is the time to collect tail hair and determine parentage and mutations of Myostatin (DM genes).

    • The thinking is – do you really need the parentage of those bull calves that will be culled?

    • Is the parentage of the approved bull calves not good enough to show which stud sires are performing?

    • If you do single bull mating, parentage is “known” anyway without any DNA confirmation. If you do multiple bull mating, DNA testing should be used to determine parentage.

      It is important to understand that all approved bulls should have parentage confirmed by DNA but not all approved bulls should be DNA tested for DM.

      The long explanation above is to set off the cost of testing for DM genes against the savings of not doing DNA parentage confirmation for the culled bulls.

  7. Now that you have confirmed the DM status of the bulls, the following are important:
    • Do not cull the approved bulls that are gene carriers. Make the DM status of the animals known to the prospective buyers, be it at auctions or on the farm sales (out of hand). Often, farmers prefer the carrier bulls in a terminal breeding system.

    • It is important to know that when DM carrier bulls are used on clean cows, only 25% of the progeny may inherit the DM gene and they will thus be heterozygotic (single gene) carriers. 75% of the off-spring could be clean.

    • DM carrier bulls often breed good clean bulls and heifers as part of the 75% clean off-spring

  8. Currently it is hard to find and quite expensive to buy high quality clean bulls.

    We have not been aware of the presence of myostatin mutations in the Bonsmara and a number of the “significant stud sires” in the industry, are carriers of the genes. It will be foolish to use an inferior bull just because it is clean, and discard the existing DM carrier bull which may be of very high quality.

  9. Try to use only clean bulls in future. This will significantly decrease the frequency of the DM genes in the herd.

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