Effect of different energy levels in feed and slaughter weights on carcass and chemical composition of Lori-Bakhtiari ram lambs

In this study the effect of three slaughter weights (SWs) of 45, 52.5 and 60 kg and two different feed metabolizable energy levels (MELs) (2.64 and 2.4 Mcal/kg DM) were evaluated. At the beginning of the experimental period the BW of 53 lambs on average was 35.7 ± 3.8 kg and 165 days of age. Fifty-three lambs were randomly assigned to a 2 × 3 factorial design. Lambs were slaughtered according to their SW. Weights of wholesale cuts and bone, fat trim and trimmed meat of each cut were recorded. Percent of moisture, CP, EE, ash, Ca and P were determined in each de-boned carcass. MEL and SW did not influence the mean dressing percentages. MEL did not influence loin eye muscle area (LEMA) and back fat (BF), but there was a difference (P < 0.01) between SW of 45 and 60 kg for LEMA and BF. Shoulder and flap were influenced by MEL and SW (P < 0.05). The mean meat, bone, subcutaneous fat and tail fat percent were not influenced by MEL, however, by different SW (P < 0.05). MEL had no significant effect on DM, CP, EE, ash, Ca and P content of the de-boned carcasses, but SWdid (P < 0.05). This study indicated that most of the carcass characteristics were not altered by lowering the energy levels, but were higher when lambs were slaughtered at 60 kg live weight, and under intensive feeding lambs of the Lori-Bakhtiari breed produced desirable carcass at 60 kg live weight. © 2003 Elsevier B.V. All rights reserved