Microbial and Fungal Phytases Can Affect Growth Performance, Nutrient Digestibility and Blood Profile of Broilers Fed Different Levels of Non-Phytic Phosphorous.

A total of 420 day old chicks were divided into seven groups (5 replicates of 12 chicks/group) fed isoproteic and isoenergetic diets. The control group was fed diets containing 0.50%, 0.45% and 0.40% of non-phytic phosphorous (nPP) in starter (1-35), grower (37-56) and finisher (57-64 d) periods, respectively. The three intermediate nPP (IntnPP) groups were fed diets with 0.40%, 0.35% and 0.30% nPP according to the growth period and were submitted to three dietary treatments: unsupplemented; supplemented with 500 FTU/kg diet of an Aspergillus niger phytase (IntnPP_fp) and supplemented with 500 FTU/kg diet of an Escherichia coli phytase (IntnPP_bp). The three low nPP groups fed diets contained 0.30%, 0.25% and 0.20% nPP and were submitted to the same dietary treatments than IntnPP to obtain LnPP, LnPP_fp and LnPP_bp groups. IntnPP and LnPP groups had lower body weight gain and feed, crude protein (CP) and metabolizable energy (ME) intake (p < 0.05) than the control. Feed conversion ratio of IntnPP was more favorable (p < 0.01) than the LnPP group. CP and ME conversion ratios worsened (p < 0.01) in IntnPP and LnPP groups in comparison to the control. The nPP conversion ratio improved (p < 0.01) from the control to the LnPP group. Fungal phytase reduced (p < 0.05) feed, CP, ME and nPP intake than the bacterial one. IntnPP and LnPP diets had a lower digestibility of CP (p < 0.01) and CF (p = 0.01) than the control. IntnPP and LnPP groups showed a higher (p < 0.05) economic efficiency than the control. Blood total protein was the lowest (p < 0.05) in the LnPP group, the control group showed the lowest (p < 0.05) level of albumin and IntnPP group had the lowest (p < 0.01) globulin level. The use of bacterial phytase increased (p < 0.01) total protein and globulin and decreased (p < 0.05) the plasma cholesterol in comparison to fungal phytase. Decreasing nPP levels in colored slow-growing broilers diet negatively affects growth performance and the use of phytase can partly alleviate these negative effects, but the efficiency of different enzyme sources (bacterial or fungal) was tied to the dietary nPP levels.