Impact of Selection and Breed on Resistance

by Ken Andries
Kentucky State University

For years producers have been told they need to utilize selective treatment and cull animals that require greater numbers of treatments.  Using the eye color score system (FAMACHA) we are able to select for resilience, but there is little evidence of the impact.

Boers had higher egg counts post-weaning

Kentucky State University started with a grade Boer herd in 2005 and added Spanish (2010) and Savanna (2011) breeds to evaluate breed differences under Kentucky’s environment.  The herds were selected for production and parasite resilience/resistance by culling any doe that did not bring a kid to weaning and number of dewormings a doe received during a 12 month period.

We moved the number of dewormings down over the years from 5 dewormings in 2008, to our current standard of culling any doe that is dewormed 3 times, or more, in a year. We started evaluating parasite loads in the kids at weaning and 60 days post weaning in 2016.

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Source:  American Consortium for Small Ruminant Parasite Control