In Iran, one of the proper ways to supply meat requirement is fattening lambs. Low biological effeciency of Iranian lambs is due to inadequate feedstuffs, feeding under standard nutritional requirements and using imbalanced rations. The present experiment was conducted to investigate the average daily gain (ADG). Feed conversion (FC), dressing percentage (DP), Carcass cuts (CC), Fat tail,. ..of Atabai and zel lambs.
In this experiment, fifty zel and fifty Atabai male lambs at 3-4 months of age, were fattend with to one of the tree rations Ilow, 0.61: medium , 0.85; and high energy, 1.18 Mcal NEg/Kg DM). The lambs in groups of 16-17 were fed for 100 days in six similar pens (2 x 3 factorial design). ADG and FC of the animals were measured at regular intervals during the trial. At the completion of the experiment the animals within each of the ration groups were slaughtered and dressing percentage, carcass cuts, fat tail,.., were measured. The results of this trial suggested that, apart from the effect of the rations, ADG of the Atabai lambs (141.5 gr) was higher than of the zel lambs (88.88 gr), but FC for both genetic groups was similar (10.89, VS 10.77). The ADG of the lambs fed with high, medium and low energy ration was 154.72, 101.61 and 64.42 gr, respectively. The difference among these mean was statistically significant (P 0.05). The highest ADG and FC were achieved with Atabai x high energy ration (210 gr, 6.56), while Zel x low energy ration had lowest ADG and FC (48.14, 13.58). There was not significant difference among dresssing percentages or carcass cuts in most of treatments.
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