The Effect of Microbial Phytase in Broiler Grower Diets Containing Low Phosphorus, Energy and Protein

One thousand two hundred and fifty sexed 21 day-old commercial broilers (Ross-308) were randomly divided into five dietary treatment groups of 250 broilers each. Each treatment group was further sub-divided into five replicates of 50 broilers (25 male and 25 female) per replicate. The treatments groups were control; low phosphorus; low phosphorus plus 500 FTU phytase/kg diet; low phosphorus, energy, protein; and low phosphorus, energy, protein plus 500 FTU phytase/kg diet. There were significant effects of dietary treatments on body weight, body weight gain, feed intake and feed conversion ratio at 21 to 42 days. The body weight and the body weight gain of the broilers fed the control and low phosphorus plus phytase diet were heavier than other treatment. Feed intake of broilers was not affected by the supplementation of phytase to the low phosphorus diet at 21 to 42 days. Feed conversion ratio of broiler fed on low phosphorus, energy and protein diet plus phytase was significantly better than that of broilers fed on low phosphorus, energy and protein diet. Neither phytase supplementation nor diet nutrient density and dietary phosphorus level had a significant effect on broiler mortality. The percentage of tibia ash and phosphorus was significantly increased by the addition of microbial phytase to low phosphorus, energy and protein diet. This study demonstrates that microbial phytase can compensate for reduced available phosphorus levels, but could not compensate for reduced dietary protein and energy. © 2006, Japan Poultry Science Association. All rights reserved