ABSTRACT
The effect of increased levels of metabolisable energy with glycerine or soybean oil was evaluated in the performance of broilers at four growth stages (1 to 7, 8 to 21, 22 to 33 and 34 to 42 days), in addition to the carcass and cut yield. A total of 2,400 birds were used in a completely randomised design in a 2 x 4 factorial scheme (two sources x four energy levels), with five replications. The treatments were determined by including glycerine or soybean oil at intervals of 75 kcal/kg of metabolisable energy in the diet: the first level with 75 kcal less than the requirement, the second corresponding to the requirement for each stage (2925, 2980, 3050 and 3100 Kcal), and the third and fourth levels with 75 kcal and 150 kcal more than the required value for the stage under evaluation. The metabolisable energy requirement for broilers, irrespective of the energy source (glycerine or soybean oil), was estimated at 3,075, 3.130, 3,200 and 3,250 kcal ME/kg feed, for stages 1 to 7, 8 to 21, 22 to 33 and 34 to 42 days respectively. However, the use of glycerine as a source of increased energy promoted better performance efficiency during the first two stages (1 to 7 and 8 to 21 days of age).
Key words:
Poultry farming; Fat; Energy sources; Performance