Scientists have pinpointed the genetic mutation that causes lambs to develop large and muscular rumps-a trait known as callipyge, from the Greek for ‘beautiful buttocks.

What is Callipyge phenotype?

Callipyge is a muscle hypertrophy phenotype in sheep (Jackson and Green 1993), resulting from an apparent single locus mutation in the telomeric region of ovine chromosome 18 (CLPG; Cockett et al. 1994).