Investigation of growth and carcass characteristics of pure and crossbred Awassi lambs

The aim of this experiment was to study the growth performance of both ram and ewe lambs, and the carcass characteristics of ram lambs of five genotypes: Awassi (A), F1 Charollais–Awassi (CA), F1 Romanov–Awassi (RA), B1 Awassi–(Charollais × Awassi) (ACA) and B1 Awassi–(Romanov × Awassi) (ARA). One-hundred lambs (50 females and 50 males) were separated into 10 groups according to sex and genotype from weaning until the end of the experiment. Birth and weaning weights were recorded for all animals; live weight was recorded for all animals on bi-weekly intervals between 2 and 8 months of age. At 8 months of age, 6 ram lambs from each genotype (a total of 30 ram lambs) were randomly chosen for slaughter. Birth weights were similar while weaning weights differed among the five genotypes being greater for the CA. Post-weaning live weights differed among genotypes and according to lamb's sex (P < 0.01). Genotype and lamb sex had significant effects on the total weight gain and average daily gain (ADG) from birth till the end of the experiment. The CA lambs outperformed other genotypes while ram lambs had better performance than ewe lambs. The greatest ADG for all genotypes occurred during the period from weaning to 5 months of age (fattening period). At slaughter, final live weight was found to be significantly affected by genotype; the greatest weight was recorded for CA genotype (62.5 ± 4.0 kg). Slaughter weight and hot and cold carcass weights differed significantly among the five genotypes with Awassi having the lightest weights. Dressing-out percentage was also affected by genotype with CA lambs having the greatest value. Awassi had lower eye muscle depth, the shorter carcass (P < 0.001), least fat tissue depth, lowest linear measurements and the greatest fat tail percentage compared with the remaining genotypes. Shoulder and rack percentages differed among the genotypes with Awassi having the lowest values. In the dissected leg cut, muscle to bone ratio differed among the genotypes with CA having the highest ratio. Awassi lamb meat had lower (P < 0.05) dry matter and crude fat (on as wet basis) percentages than the other genotypes. Results of this study indicate that crossbreeding Awassi with exotic breeds improves growth rate and meat production.