*2.7. Carcass Characteristics*

The *longissimus* muscle area (LMA) and the backfat thickness (BFT) located between the 12th and 13th ribs of the lamb were measured on day 55 of the experiment using a Sonovet 600 (Medison, Inc., Cypress, CA, USA) with a 7.5 Mhz transducer [31]. After the last weighing (day 56 of the experiment) the lambs were fasted for 18 h before being slaughtered. All lambs were slaughtered on the same day. The slaughter process was conducted in a commercial slaughterhouse in accordance with standard procedures of the Official Mexican Standard (NOM-033-SAG/ZOO-2014). Lambs were stunned (captive bolt), exsanguinated and skinned. Immediately after the slaughter, the hot carcass weight was registered (HCW). The hot carcass yield (HCY) was determined through HCY = (HCW/FBW) ∗ 100, as it was described by Zimerman et al. [32]. In addition, the skin, head, legs, testicles, rumen (empty), liver, spleen, kidneys, heart, lungs, small intestine (empty), and large intestine (empty) were each weighed separately.
