This study was aimed at evaluating the effect of the use of different roughage:concentrate ratios on the performance, carcass characteristics and gastrintestinal content, and realizeing an economic evaluation of the feeding of feedlot lambs in termination phase. Twenty-five male lambs, of the Texel breed, non castrate, weaned with 60 days of age, were used. They were randomly distributed in five treatments, composed by different roughage:concentrate ratios, being: 30:70; 40:60; 50:50; 60:40 and 70:30, on dry matter basis (DM). The roughage used was the Tifton-85 hay and the concentrate was composed by commercial ration, soybean meal, limestone and dicalcium phosphate, in different proportions. The experimental period was 80 days long, when the animals were slaughtered. The increase of the roughage and the decrease of the concentrate on the diets promoted a linear reduction (P<FONT FACE=Symbol>£</FONT>0.01) on the daily weight gain and slaughter live weight. The consume of dry matter and food conversion were influenced in a quadratic way by the increased of the relation roughage:concentrate. The increased of the roughage and the decreased of the concentrate on the diets promoted a linear decreased (P<FONT FACE=Symbol>£</FONT>0.01) on the hot carcass weight, hot carcass yield and weight of hindquarter, neck, rib, shoulder and of empty green viscera. It was verified a linear increase of the proportions of full green viscera (P<FONT FACE=Symbol>£</FONT>0.05) and the gastrintestinal content (P<FONT FACE=Symbol>£</FONT>0.01) with the increase of the proportion of roughage and decreased of the concentrate in the diets. The sales profitability of the live lambs was not different between the treatments, showing an average value of R$ 57.00 per lamb. There was a linear decrease (P<FONT FACE=Symbol>£</FONT>0.05) in the profitability in the sale of lamb’s carcass with the increased of roughage and decrease of concentrate in the diets.
live weight components; confinement; sheep; nutrition
