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的添加方式对肉仔鸡生产性能与胫骨灰分、钙、磷含量的影响。试验选取900只22至35日龄的雄性肉仔鸡，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，涵盖三种钙：有效磷比例（4.5:1.0、6.0:1.0及7.5:1.0）、三种不同来源植酸酶的添加方式（单独添加细菌源或真菌源植酸酶、联合添加细菌与真菌源植酸酶），并设置1组基础对照日粮。无论日粮钙：有效磷比例如何，单独添加细菌源植酸酶的饲料转化率均优于真菌源植酸酶，但与联合添加细菌及真菌源植酸酶的组间无显著差异。不过，无论添加何种植酸酶，7.5:1.0的钙：有效磷比例均会降低饲料转化率。当日粮采用4.5:1.0的钙：有效磷比例并添加真菌源植酸酶，或采用4.5:1.0、6.0:1.0的钙：有效磷比例并添加细菌源植酸酶时，骨骼磷沉积效果最佳。综合来看，若同时考量饲料转化率、骨灰分含量及胫骨磷含量三项指标，采用4.5:1.0或6.0:1.0的钙：有效磷比例并添加1500 FTU·kg⁻¹细菌源植酸酶的日粮，或是采用4.5:1.0的钙：有效磷比例并添加真菌源植酸酶且有效磷含量仅为1.0 g·kg⁻¹的日粮，可获得更优的试验结果。