We evaluated the effects of 6-phytases on the growth performance of broilers (UK Chunky) under the recommended supplier-application dosage of each phytase. A nutritionally sufficient standard diet was administered as the base diets in the positive control feed. The diet in the negative control feed was designed by reducing total phosphorous, non-phytate phosphorus, and calcium by 0.1% to evaluate the effect of the nutrient restriction on broilers. Four 6-phytases were added to negative control feeds at the level of the recommended dosage of each product to compare the effect of phytases on broiler technical performance, tibia ash, and feed digestibility. Nine hundred one-day-old broiler chicks (males and females) were distributed in a completely randomized design composed of six treatments and three replicates of 50 chicks each. Chicks were fed ad libitum for 49 days. Body weight gain and feed intake were recorded on days 21 and 49, tibia ash was measured on day 21, and apparent ileal digestibility of dry matter, crude protein, and total phosphorus were analyzed on day 49. Birds reared with test feeds supplemented with phytase showed higher body weight gain and feed intake compared to those of the negative control birds. No significant differences in traits were observed among different phytase treatments. Similarly, the percentage of tibia ash increased when phytase was supplemented, resulting in higher bone levels compared to that of the positive control. The apparent ileal digestibility of crude protein and total phosphorus was enhanced by supplementing negative control diets with phytases.
Keywords: broiler; ileal digestibility; phytase; tibia ash.