The slaughter of heavy pigs (120 to 130kg BW) provides relatively bigger carcasses and a higher amount of meat, but has the disadvantage of a higher fat deposition, given that animals have higher food intake while protein deposition remains the same. Qualitative feed restriction is a technique that provides caloric intake control, diluting the diet energy with a fibrous ingredient. Our aim was to test the effects of diets containing increasing concentrations of insoluble fiber as part of a qualitative feed restriction program on carcass traits. Thirty 2 barrows (commercial crossbred; initial BW 78.53 ± 11.02kg), were assigned to 4 dietary treatments (ad libitum) with 8 replicate pens per treatments and one animal per pen in a randomized block design: control (corn and soybean meal based; 3230 kcal/kg calculated ME, 13.9% CP, 15.5% insoluble fiber) and 3 diets with increasing concentrations of insoluble fibers (20, 25 and 30%; from purified cellulose), and consequently decreased concentrations of calculated ME. The slaughtered happened when BW means were 133.30 ± 11.59kg. The yields were calculated based on the final BW, the backfat thickness, loin eye and fat area were measured at last ribs, in the insertion of the last thoracic vertebra to the first lumbar. Data were analyzed by ANOVA using GLM procesure of SAS, polynomial regression were used to determine the effect of insoluble fiber. We observed linear reduction (P < 0.05) to backfat thickness and fat area, moreover, linear increase to meat:fat ratio. There were no differences in final BW, yield, lean meat, loin eye area and ham yield. In conclusion, using up to 30% of insoluble fiber in diets of heavy pigs as part of a qualitative feed restriction program reduces carcass fat without altering other carcass traits. Table 1. Carcass traits from swine fed different levels of insoluble fiber

Item	Experimental diets (% IF)				SEM	Effect of IF
15.5	20	25	30
Final BW, kg	136.18	132.38	131.83	130.97	2.23	—
Yield, %	80.83	80.54	79.72	79.14	0.76	—
Lean meat, %	55.53	54.53	56.11	57.39	0.75	—
Backfat thickness, mm	33.97	31.62	32.16	26.78	0.90	Linear
Loin eye area, cm2	44.14	39.14	43.14	45.43	1.36	—
Fat area, cm2	28.86	33.86	23.29	23.14	1.48	Linear
Meat:Fat	1.63	1.16	1.97	2.14	0.12	Linear
Ham yield, %	29.22	27.93	30.75	29.04	0.55	—