ِAn experiment was conducted to determine and compare the differences in productive and physiological performance of broiler chicks fed three different dietary energy levels under two housing systems on floor pens and in cages. The model trial was conducted with 180 Hubbard broiler chicks from 0 to 5 weeks of age, chicks were distributed in a completely randomized design with 3(E) X 2 (R) factorial arrangement 3(E) ME levels: low, medium and high and 2(R) housing systems (floor pens and cages), resulting in a total of 6 treatments with 3 replicates of 10 chicks each.
The results indicated that:
- Productive performance of broiler chicks: live body weight (LBW), daily weight gain (DWG), feed intake (FI), feed conversion ratio (FCR), performance index (PI) and production efficiency factor (PEF) were not affected by the (E) interaction between three energy levels and two housing systems, (E) energy levels and (R) housing system at whole experimental period.
- Blood plasma parameters were not affected by E interaction between energy levels and housing system except plasma albumin. Floor pens that raised broiler chicks had significantly (P≤0.05) lower plasma albumin than that those of the cage reared ones, being (2.01 vs. 3.03 g/dl).
- Carcass traits and relative weight of lymphoid organs were not affected by R * E interaction, except dressing to cook percentages.
- Feeding economical efficiency showed that, floor pens that raised broiler chicks had higher mean (REE) than those of the cages reared ones and REE was improved for broiler chicks only by feeding high energy level (floor pens) or low energy level (cages).