A total of 60 barrow pigs (89.1 ± 4.2 kg) was used to evaluate five levels (0, 5, 10, 15 and 20%) of qualitative feed restriction, resulting in values of 3,407, 3,420, 3,060, 2,890, and 2,720 kcal/kg DE in the diet. Ten animals were slaughtered at the beginning of the experiment to determine the initial body composition, while the others were fed with the experimental diets until reaching 128 kg of body weight. A randomly block design was used to control the initial weight differences, with ten blocks and five treatments (experimental diets) and one animal per experimental unit. Performance and carcass characteristics and serum parameters of pigs were submitted to analysis of variance and with posterior analysis of regression in function of qualitative restriction levels of diets. The increase of feed qualitative restriction levels did not affect the daily feed intake but linearly reduced the daily digestible energy intake and the daily weight gain, resulting in worse feed conversion and better efficiency of energy utilization by pigs. The levels of qualitative restriction produce a linear reduction of serum triacylglycerol levels and of back fat thickness, and an increase of percentage and amount of lean meat and bonus carcass index, but did not alter the daily lean meat gain of pigs. The use of qualitative feed restriction is efficient to reduce the pig energy intake and fat deposition, without change the capacity of lean meat production.
carcass quality; carcass merit; energetic restriction; fiber; heavy pigs; lipid metabolism
