Supplementation of fungal and/or bacterial phytase in broiler diets formulated with reduced phosphorus level and different calcium contents

ABSTRACT The objective of the current study was to evaluate the effects of three calcium:available phosphorus (Ca:aP) ratios and different supplementation with phytases from different origins on performance and ash, Ca, and P contents in the tibia of broilers. A total of 900 male broilers (22 to 35 days old) were fed ten dietary treatments in a completely randomized design. A 3 × 3 + 1 factorial scheme was used, corresponding to three Ca:aP ratios (4.5:1.0, 6.0:1.0, and 7.5:1.0) and three different supplementations with phytases from different origins (isolated or combined supplementation with bacterial and fungal phytase), plus a control diet. Regardless of the dietary Ca:aP ratio, the isolated use of bacterial phytase provided better feed conversion than the fungal phytase but did not differ from combined supplementation with bacterial and fungal phytase. However, regardless of the supplemented phytase, the 7.5:1.0 Ca:aP ratio decreased the feed conversion. Best results for bone P deposition were observed using diets containing the 4.5:1.0 Ca:aP and fungal phytase or the 4.5:1 and 6.0:1 Ca:aP ratios using the bacterial phytase. In general, when the parameters of feed conversion, bone ash, and P content in tibia are considered together, diets containing a 4.5:1.0 or 6.0:1.0 Ca:aP ratio and 1,500 FTU kg−1 bacterial phytase, or a 4.5:1.0 Ca:aP ratio using fungal phytase and only 1.0 g kg−1 available phosphorus provide better results.

摘要 本研究旨在评估三种钙：有效磷（Ca:aP）比例以及不同来源植酸酶（phytase）的添加方式对肉鸡生产性能及胫骨灰分、钙和磷含量的影响。试验选取900只22至35日龄的雄性肉鸡，采用完全随机设计，设置10种日粮处理方案。试验采用3×3+1因子设计方案，对应三种Ca:aP比例（4.5:1.0、6.0:1.0和7.5:1.0）以及三种不同来源植酸酶的添加模式（单独添加细菌植酸酶、单独添加真菌植酸酶或联合添加细菌与真菌植酸酶），另设对照组日粮。无论日粮的Ca:aP比例如何，单独添加细菌植酸酶的饲料转化率均优于单独添加真菌植酸酶，但与联合添加细菌和真菌植酸酶的处理组无显著差异。不过，无论添加何种植酸酶，7.5:1.0的Ca:aP比例均会降低饲料转化率。当日粮采用4.5:1.0的Ca:aP比例并添加真菌植酸酶，或采用4.5:1与6.0:1的Ca:aP比例并添加细菌植酸酶时，可获得最佳的骨骼磷沉积效果。总体而言，若综合考量饲料转化率、骨灰分含量及胫骨磷含量这三项指标，采用4.5:1.0或6.0:1.0的Ca:aP比例并添加1500 FTU·kg⁻¹细菌植酸酶，或采用4.5:1.0的Ca:aP比例并添加真菌植酸酶且有效磷含量仅为1.0 g·kg⁻¹的日粮，可获得最优试验结果。