GROWTH-PERFORMANCE AND CARCASS CHARACTERISTICS OF LAMBS RAISED ON VARYING PROPORTION OF ROUGHAGE AND CONCENTRATE

This study was conducted on native and crossbred weaner lambs to asses s their growth response and carcass traits under intensive feeding for 90 days on composite rations having 35 (G1), 45 (G2), 55 (G3) and 65 (G4) % Zizyphus nummularia leaves in the diet. Initial body weights we re similar in the 4 groups. The final weights and ADG were higher (P<0 .01) in G1, G2 and G3 compared to G4. Feed conversion efficiency was h igher (P<0.01) in G1 (16.2%) and G2 (15.1%) than in G3 (13.4%) and it was lowest in G4 (12.0%). Crossbred had better growth rate. However, t heir feed conversion efficiency was inferior to native lambs. DMI prog ressively increased with increase in roughage component, whereas DM di gestibility followed reverse trend. Wool yield (6 monthly clip) was si milar in treatment groups and it was higher (P<0.01) in crossbred (1.1 9 kg) compared to their native (0.81 kg) counterpart. The dressing per centage (51.9%) and dressing yield inclusive of edible offals (57.3%) and cutability of standard cuts were similar in the treatments and the two genotypes. The carcass fat content of crossbreds was higher than of native lambs and irrespective of treatment regimen the lambs with h igher finishing weight had higher carcass fat. The cost of feed input/ kg gain in weight was similar in G1 (Rs 25.35) and G2 (Rs 25.16) and h igher in G3 (Rs 26.17) and G4 (Rs 27.14) whereas it was lower in nativ e (Rs 25.03) than in crossbred (Rs 26.53). The results indicated that for intensive mutton production quality feed input commensurating with higher rate of gain will fetch better returns and both native and cro ssbred lambs can be effectively utilized for economic mutton productio n.