We started a program in 2007 to try and develop our herd into a more worm resistant
breed. We are very excited about the progress we have seen as we enter 2013. Our
program was basically to understand which animals needed more de-worming throughout
the year and which ones needed little or no de-worming. We started out doing a monthly
maintenance check at the beginning of each month and document our findings according
to our Monthly Management program. We started identifying animals that seemed like
they never needed worming and others that seem to have a worm problem more than others.
We started culling the animals that needed more de-worming. Animals needing less
de-worming are the genetics that we want to keep. We often see the offspring from
those animals are more worm resistant also.
After a few years, we no longer do our monthly program every month. We can now tell
if there are some changes in the animals and if we don’t see any changes, we may
bypass the program if no vaccines are needed at the time. It is clear to tell that
we are de-worming far fewer animals now than we did back in 2007. We also follow
the refugia program now. The basic focus is to ensure we have animals in the pastures
that have not had much de-worming and animals that have had some de-worming. When
the worm larvae from each type of animal is ingested, some worms will be less resistant
and some more resistant to the larvae. Those larvae will breed and result in worm
eggs that are not as resistant to the worms. This keeps the average worms in the
herd to be less resistant.