Effect of feed form, pellet diameter and enzymes supplementation on growth performance and nutrient digestibility of broiler during days 21-37 of age
A total of 420 21-day-old broilers were wing banded and randomly distributed among 60 cages of 7 birds per cage during days 21-37 of age. A factorial design (4×3) was used in which there were four feed forms (mash vs. pellet diet with diameter 2-2 mm, 2-3 mm and 3-3.5 mm, respectively) and three enzyme treatments (unsupplemented, phytase, phytase plus multi-enzyme). Each treatment was replicated 5 times with 7 broilers per replicate. Body weight gain of broilers fed 2-3 mm-diet was significantly greater than that of those fed mash diet and 2-2 mm or 3-3.5 mm pellet-diet. Feed conversion ratio was the best in broilers fed 2-3 mm and 3-3.5 mm pellet-diets. However, feed intake was significantly lower in broilers fed pellet-diets than that of those fed the mash diet. The production index and economic efficiency were significantly higher in groups fed 2-3 mm pellet diameter compared to those fed 2-2 mm and 3-3.5 mm pellet diets. Digestibility of crude protein, ether extract, crude fibre and crude ash were significantly and similarly greater in groups fed pellet diets in comparison with those fed mash diet. Enzyme supplementations significantly and similarly increased growth and production index whereas improved feed conversion ratio and economic efficiency than the control group and this concurred with greater digestibility of crude protein, ether extract and crude ash. However, multi-enzymes plus phytase induced greater effect on the production and economic traits than phytase alone showing synergetic effects. Pellet diet at 2-3 mm supplemented with multi-enzyme plus phytase resulted in the highest performance and nutrient digestibility of broilers during day 20-37 d of age.