Sources and levels of glycerin for broilers from 22 to 35 days

The aim of this experiment was to evaluate the performance and carcass yield of broilers from 22 to 35 days old, receiving diets with different levels of soybean glycerin (SG) and semipurified glycerin (PURG). A total of 792 male broilers of the Cobb 500 strain, a 4x2+1 factorial arrangement was used designed in randomized blocks by the weight of the birds, with four inclusion levels (17.5, 35.0, 52.5 and 70, 0 g/kg) of two glycerins (SG and PURG) in the diets and one glycerin-free control treatment. Four replicates per treatment of 22 birds were used for each experimental unit. Feed intake and carcass yield were not influenced by the levels and sources of glycerin. There was an interaction between levels and sources of glycerin for the weight gain (WG) where a quadratic effect was observed for the SG and the largest WG obtained with the addition of 35.50 g/kg of SG. There was an interaction between glycerol levels and sources for feed conversion (FC) and a quadratic effect was observed for both sources; the level of 35.5 g/kg of SG promoted a better FC and the level of 39.44 g/kg of PURG promoted the worst FC. For the thigh and drumstick yield (TDY), there was an interaction between levels and sources of glycerin, and the inclusion of 40.21 g/kg of SG provided a lower TDY. There was also interaction for breast yield (BY), where the highest levels of BY were 35.15 g/kg of SG and 43.69 g/kg PURG. The percentage of abdominal fat (AF) was influenced only by the sources of glycerins, where the lowest percentage of AF was promoted by PURG. Regarding the control, the inclusion of 70 g/kg SG provided the worst PG, TDY and BY. In conclusion, the addition of 35.5 g/kg of SG and 70.0 g/kg PURG provides the best performance outcome of birds at 22 to 35 days old, within the evaluated levels.   Key words: Poultry, commercial cuts, glycerol, abdominal fat.