Effect of crossbreeding on growth, feed efficiency, carcass characteristics and sensory traits of lambs from Lori-Bakhtiari and Romanov breeds

This study compares the growth performance, carcass characteristics, and sensory traits of pure lambs of Lori-Bakhtiari fat-tailed sheep (LL genotype) and their crosses with Romanov tailed sheep breed (RL genotype). After weaning, the average daily gain (ADG) and feed conversion ratio (FCR) of male lambs were recorded at a fattening period of 80 days. Twenty-three male lambs were slaughtered, and the left sides of the carcasses were separated into six pieces to determine the lean meat, bone, subcutaneous fat (SCF), and inter muscular fat (IMF). Genotypes had different ADG (LL: 296.50 ± 11.57 v. RL: 249.11 ± 12.92 g/day) and FCR (LL: 6.12 ± 0.26 v. RL: 6.98 ± 0.30) (P < 0.05). The fat-tail weight in the crossbred lambs was about 80% less, but the weights of SCF and IMF were 55% and 33% greater than the purebred lambs, respectively (P < 0.01); however, the difference in the back-fat thickness (12-13th rib) was not significant between the two genotypes (LL:4.29 ± 0.32 v. RL:4.62 ± 0.37 mm) (P = 0.41). While abdominal fat (AF) was 65% greater than that of the purebreds (P < 0.001), the total body fat in the crossbred lambs was about 34% less than the purebreds (P < 0.001); it had been displaced with about 23% more lean meat (P < 0.001). A trained panel evaluated the tenderness and flavor of the LL and RL meat through a sensory evaluation. Tenderness score (LL: 6.75 ± 0.94 v. RL: 5.16 ± 0.94) was significantly affected by the genotype (P < 0.01); however, the panelists could not detect a significant difference in flavor score between the two genotypes (LL: 7.01 ± 0.82 v. RL: 6.85 ± 0.82). It can be concluded that crossbreeding the indigenous Lori-Bakhtiari sheep with Romanov breed can significantly improve carcass traits and increase meat production. The present data showed that, even though crossbred lambs could not compete with purebred in terms of ADG, FCR, and tenderness, the lower total body fat in crossbred lambs (34%) compensated the inferior high fat in the Lori-Bakhtiari breed.