This experiment was carried out at the Grdarash field belongs to the Agricultural researches directorate/general Agriculture directorate-Erbil in September (2007)، 27 Arabic lambs aged (5-6 months) With average initial weight (39.178 Kg/lamb) were used. Lambs were divided in to (3) groups (9 lambs/group). Control group was fed on (85% barely، 10% bran and 5% straw)، and second and third groups were fed on various by-product in replacement with barely in loss and block shape respectively.
The total gain of three groups were (392708.32، 634826.52 & 445613.72 ID respectively)، average simple returned (0.33، 0.47 & 0.38 respectively)، average fund return (3.06، 2.139 & 2.66 times respectively)، total fund return period (183.6، 128.34 & 159.6 days 238.52 & 250.52 days respectively)، forage productivity (26.89، 31.74 & 29.74 respectively). At sensitive estimating total gain for three groups were (336498.6، 488257.6 & 391816.6 ID respectively)، average fund return (0.317، 0.466 & 0.373 times respectively)، average fund return (3.153، 2.148 & 2.676 times respectively)، total fund return period (189.18، 128.88 & 160.56 days respectively) and forage productivity (17.07، 21.41 & 20.06 respectively)
.It was found the lambs were fed on different by-product in loss or block type were more economical than lambs fed on barely and the effect of changing price representing by sensitive it's effect was less negative in lambs fed on different by-product in loss or block type than lambs in control group fed on barely only at estimating average fund return and total fund return period.
