This study was performed using 9 R1 BBA lambs (5 lambs having 6 lumbar vertebrae and 4 lambs having 7 lumbar vertebrae). R1 BBA lamb is a crossbreed genotype, obtained via the crossbreeding of Bafra (75%) and Akkaraman (25%) breeds at the Gozlu state farm (38° 29' N and 32° 27' E, 1020 m of altitude) in the central Anatolia region of Turkey. Bafra rams mated with Akkaraman ewes, and F1 ewes were then backcrossed with Bafra rams to produce the second cross (R1) lambs.
Lambs were separated from dams at an average 90 days of age (weaning) and fattened during 84 days with ad-libitum concentrate fed (15% crude protein and 2,800 kcal/kg ME) and 300 g alfalfa hay per animal/day. Finally, lambs having 6 and 7 lumbar vertebrae were slaughtered at a mean weight of 42.950 ± 0.877 and 42.175 ± 0.893 kg, respectively.
Slaughtering and Carcass characteristics
Lambs’ weights were determined 12 hours before slaughter, and then when fasting just before slaughter. Head, skin, feet, heart, lungs, liver, spleen, testicles, full digestive tract, empty rumen, empty intestine, trachea-esophagus, omental fat, and mesenteric fat were removed and weighted after bleeding. Then, the carcass measurements were taken.
The length of the carcass (between the caput humeri and tuber ischia), the back (between the distal cranial points of the shoulder and the tail), the leg internal (between the cranial edge of symphysis pubis and the tarsal–metatarsal joint), the leg external (between the articulatio coxae and the tarsal–metatarsal joint), the rump (between the tuber coxae and tuber ischia) and the neck (between the distal cranial point of the shoulder and cranial point of the neck) were measured on the carcasses. Similarly, the width of the leg (distance between the two gigots at the junction point alignment of the legs), the chest (distance between the left and right of the extremitas proximalis scapulas) and the rump (distance between the articulationes coxae) were obtained on the carcasses. Then, leg circumference (over the articulationes coxae on the carcass), chest girth (over the caudal points of the scapulas), rump girth (over the articulationes coxae), chest depth (distance between the sternum and the withers) were taken. Carcass compactness and leg compactness indexes were calculated by the formulae: cold carcass weight/length (kg/m) and leg weight/length (kg/m), respectively (Santos et al., 2007).
Gastrointestinal tracts were weighed both full and empty to identify gastro-intestinal contents weights, and empty body weight was calculated using these values. Consequently, dressing percentages were calculated based on slaughter weight and empty body weight. The carcass body (including perinephric–pelvic fat and kidneys) was chilled at 4°C for 24 h and weighed. To measure the eye muscle (MLD: musculus longissimus dorsi) area (cm2), it was drawn onto the transparency sheet at the level of the 12th and 13th rib 24 h after the slaughter, and this figure area was calculated using the AutoCAD software (version 2019). At the same time, the fat depth was measured from subcutaneous fat using a caliper in this region.
After this period, tail, perinephric–pelvic fat and kidneys were separated from the carcasses, and the carcasses were symmetrically divided through the columna vertebralis. Left and right side of the carcass were weighed, and left side was cut into six sections (leg, foreleg, back, loin, neck and breast + flank) according to the Akçapınar (1981). These individual cuts were grouped by first quality (leg, back, and loin), second quality (foreleg), and third quality (neck and breast + flank) according to the Díaz et al. (2006). Each individual cut piece was dissected and weighed as the lean, bone, fat, and remainder.