Yes it is. Using inbred mice allows you to use fewer mice as the variability due to the genetic background is reduced. The more variability in your system the more individuals you need to see a statistically valid difference due to treatment. The more you have to test the more the cost.<p>None of this would matter if we were developing cures for diseases of C57BL&#x2F;6 mice [1], but we are actually interested in developing cures for humans who are not inbred (well in most places). We need our animals models to match as closely as possible to humans and using inbred mice is not a good match.<p>1. <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;C57BL&#x2F;6" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;C57BL&#x2F;6</a>