ABSTRACT This study evaluated the effects of graded dietary phytase (PHY) inclusion on feed intake (FI), weight gain (WG), feed conversion ratio (FCR), nitrogen-corrected apparent metabolisable energy (AMEn), nutrient and mineral utilisation, and phytate degradation in growing turkeys. A positive control (PC) diet was formulated to meet or exceed breeder recommendations for nutrient content. A negative control (NC) diet was reformulated from the PC to contain the same calcium (Ca) to P ratio, but a reduced total P. The NC diet was subdivided and supplemented with PHY at 0, 100, 1000, 10,000, or 100,000 FTU/kg, resulting in six experimental diets. Seventy-two female BUT Premium turkey poults (mean body weight 1,885 g; SD ± 210 g) were randomly allocated to 36 raised-floor pens (two birds per pen; 0.36 m2 per pen). Each diet was fed for 9 days, from 68 to 77 days of age to six replicate pens following randomisation. Birds fed the NC diet exhibited significantly reduced FI, WG, dry matter retention (DMR), and AMEn compared with birds fed the PC diet, confirming the adverse effects of marginal phosphorus supply. Supplementation with PHY at inclusion levels ≥1000 FTU/kg largely alleviated these deficiencies. Increasing dietary PHY concentration resulted in significant positive dose-dependent responses in WG, FCR, DMR, nitrogen retention, and AMEn. Marked reductions (p < 0.001) in excreta inositol phosphates (IP) were observed at PHY doses ≥1000 FTU/kg. Concentrations of IP and free inositol (IN) followed expected responses to increasing PHY dose, involving linear and quadratic components. Mineral retention coefficients were generally lower in turkeys fed the NC diet than in those fed the PC diet, except for phosphorus retention, which did not differ between control diets. Increasing PHY dose produced significant positive linear responses (p < 0.001) in the retention of calcium, magnesium, iron, potassium, manganese, zinc, and phosphorus, particularly at ≥1000 FTU/kg, Overall, the results confirm that turkeys respond to high PHY inclusion in a manner broadly consistent with broilers. Very high PHY levels (super- and mega-doses) provided continued additional benefits for growth performance beyond 1000 FTU/kg, along with continued improvements in nutrient retention, and the data suggest the optimum dose was beyond that investigated in this study.

This study investigated the effects of phytase (PHY) and phosphate-solubilizing Bacillus (PSB) isolates on maize growth and phosphorus (P) acquisition in low-P red soil, under conditions with or without organic P application. A pot experiment demonstrated that the combined application of organic P with exogenous PHY and PSB significantly enhanced maize agronomic traits, root morphology, rhizosphere properties, and P mobilization. Compared to the P-free control, organic P application alone increased plant height, stem diameter, dry matter, and P uptake by 9.9%, 5.4%, 23.2%, and 34.6%, root surface area, volume, and branching increased by 39.7%, 26.7%, and 44.7%, while average root diameter decreased by 19.5%, respectively. Exogenous phytase treatment was more effective than bacterial adding in enhancing P activation and uptake, increasing maize P absorption by 55.4% and 47.3% with and without sodium phytate, respectively. Redundancy analysis indicated positive correlations between root traits (root tips, surface area, volume) and P uptake, and between Olsen-P, resin-P, NaHCO₃-Pi, and enzyme activities. The results suggest that combining organic P with exogenous phytase effectively mobilizes native soil P pools, improves maize growth, and increases P use efficiency, offering a sustainable strategy for P management in low-P red soils.

Effect of supplementation of phytase and its combination with xylanase, amylase, and protease on growth performance, carcass quality and nutrient utilization of yellow-feathered broilers fed diets with lower nutritional density

Plant-based meat analogs, particularly those produced by high-moisture extrusion, are prone to quality deterioration during frozen storage due to poor freeze–thaw stability. This study aimed to develop a synergistic stabilization strategy for soy protein isolate (SPI)-based extrudates using glucose oxidase (GO), phytase (PA), and tamarind gum (TG). The effects of individual additives (GO, PA, TG) and their combination (GO + TG) were systematically evaluated over seven freeze–thaw cycles, with a pure soybean-protein meat analog (PSM) as a control. The results showed that repeated freeze–thaw cycles severely degraded the control groups, leading to reduced water-holding capacity (WHC), increased hardness, and color darkening. While all additives mitigated these changes, the GO + TG combination exhibited the most pronounced protective effect, maintaining the highest WHC (0.993 ± 0.000), optimal texture (hardness 66.0 ± 0.0 N, elasticity 3.7 ± 0.0 mm), and minimal color variation. Structural analyses revealed that GO + TG effectively suppressed protein oxidation, minimized sulfhydryl loss, preserved protein secondary and tertiary structures, and inhibited the conversion of immobilized water to free water. The synergistic mechanism is attributed to the formation of a dual-network structure, wherein GO enhances covalent cross-linking and TG provides steric stabilization. This study offers a practical and effective approach for enhancing the freeze–thaw stability of extruded plant-based meat products, with potential industrial applications.

The mechanism of microbial-mediated mineralization of organic phosphorus (P) under nitrogen (N) addition in farmland soil is still unclear. To determine the effects of N addition on the composition, structure, and P transformation function of microbial community and soil P fractions in croplands, we conducted a field experiment on the Central Gansu Loess Plateau in 2017. The current study analyzed a subset of 12 plots from the 48-plot factorial experiment, comprising four levels of N addition in the absence of P fertilization. The treatment included control (0 kg N ha−1 year−1, N0), low N (75 kg N ha−1 year−1, N75), medium N (115 kg N ha−1 year−1, N115), and high N (190 kg N ha−1 year−1, N190). We determined soil P fractions and microbial properties in the 0–20 cm depth from 2019 to 2023. We found that N fertilization significantly enhanced the mineralization of soil organic P, primarily by altering microbial community structure and increasing the abundance of key taxa (e.g., RB41 and Filobasidium), which in turn boosted the activities of alkaline phosphatase (ALP) and phytase (PHY). The most pronounced stimulations in microbial biomass carbon (MBC) and ALP activity were observed under the N115 treatment. Concurrently, N addition led to substantial reductions in labile inorganic and organic P pools; for instance, the content of Ca2-P decreased most markedly under N190, by 42.82% in 2023, while labile organic P forms (LOP, MLOP, MROP) also declined significantly. Structural Equation Modeling (SEM) confirmed that N addition influenced P availability through direct pathways and indirect pathways mediated by shifts in microbial community structure, ALP, and PHY. In conclusion, our study has identified the N115 treatment (115 kg N ha−1 year−1) as the optimal level for promoting microbial-mediated organic P mineralization. To maintain soil productivity in the rain-fed agricultural systems of the Loess Plateau, we recommend applying a moderate amount of N fertilizer at this optimal rate, along with strategic P supplementation. This approach can effectively mitigate soil P deficiency and enhance the availability of P.

Impact of phytase supplementation on performance and egg quality traits in broiler breeders: A meta-analysis

Effects of phytase supplementation on energy and nutrient availability, and phytate degradation in turkeys

Abstract Variation in soil phosphorus (P) availability promotes niche differentiation among tropical tree species, yet the traits that underpin specialization on low‐P and high‐P soils (hereafter low‐P and high‐P species) remain poorly understood. Here, we examined interspecific and intraspecific variation in three types of root phosphatase enzymes and morphological traits among neotropical tree species in Panama with different habitat associations. We collected fine roots from 51 individual trees of four congeneric pairs of low‐P and high‐P neotropical tree species in the genera Cordia, Hirtella, Inga and Protium in forests on moderate to low‐P soils. We determined root morphological traits (specific root length, diameter and root tissue density) and the root surface activities of phosphomonoesterase (PME), phosphodiesterase (PDE) and phytase (PHY) enzymes, which are synthesized to release inorganic orthophosphate from soil organic P. Soil P availability was determined by measuring resin‐extractable P concentration for soils collected from the base of each tree. Low‐P species allocated more resources to produce enzymes that decompose more complex forms of P, as indicated by greater PHY activity and greater PHY:PME and PDE:PME ratios at a given soil P availability. A principal component analysis of fine‐root traits showed a greater Euclidian distance among individuals of low‐P species than among those of high‐P species, supporting the hypothesis that fine‐root traits vary more among low‐P species than among high‐P species. Synthesis. These results suggest that the specialization of tropical tree species to low‐P soil involves investment in the acquisition of complex soil organic phosphates such as phosphodiesters and phytic acid. This is possibly related to root trait divergence and indicates that variation in P acquisition strategies among tropical tree species could contribute to resource partitioning on low‐P soils.

A study was conducted using 144 Hy-Line Brown laying hens (22 weeks old) to assess the impact of exogenous enzymes on energy utilisation and ileal nutrient digestibility in diets containing 300 g/kg wheat distillers’ dried grains with solubles (DDGS). A basal diet was prepared and divided into eight treatments: a control (C) and diets supplemented with 2000 units/kg xylanase (XYL), 500 units/kg phytase (PHY), and 4000 units/kg protease (PRO), individually and in combination. The diets were fed for nine days to six coops, each housing three birds. Feed intake, weight gain, and feed conversion ratio were recorded. The feed and excreta were analysed for gross energy, and the apparent metabolisable energy (AME) was calculated. On the final day, the birds were euthanised, and ileal digesta were collected, freeze-dried, and analysed for the digestibility coefficients of dry matter (DM), nitrogen, fat, and neutral detergent fibres (NDFs). XYL supplementation improved (p = 0.035) dietary AME but did not affect (p &gt; 0.05) DM, nitrogen, fat, or NDF digestibility. No significant effects (p &gt; 0.05) were observed for PHY or PRO, and no interactions (p &gt; 0.05) were found between enzyme combinations. Substrates in experimental diets involving various enzyme combinations should be given careful consideration.

ABSTRACT The effects of exogenous phytase (PHY), xylanase (XYL) and protease (PRO) alone and in a combination, when supplemented to diets based on three field bean cultivar samples with different chemical composition, on dietary metabolisable energy (ME), nutrient digestibility, gastrointestinal tract (GIT) development, feed intake (FI), weigh gain (WG) and feed conversion ratio (FCR) were studied. Diets based on beans with lower phytic acid and fibre content had higher ME, fat (p < 0.05) and dry matter retention (p < 0.001) coefficients, which coupled with greater feed efficiency, e.g. reduced FCR (p < 0.001). Dietary PHY alone reduced FCR (p < 0.001) and XYL alone improved dietary ME (p < 0.05). An interaction (p < 0.05) between enzymes regarding FI and WG occurs, but PHY seems to be the main contributor to improved performance. There was an interaction (p < 0.05) between bean cultivars and enzymes regarding nitrogen retention (NR) as PHY produced a greater coefficient when supplemented with a low phytate diet. The overall weight of the total GIT was not changed by the enzymes or bean cultivars (p > 0.05). The changes observed in different GIT segments are unlikely to have biological significance.

This study examined the impacts of addingexogenous enzymes on the growth, nutrient digestibility, carcass composition and antioxidant enzyme activities of Catla catla fingerlings fed test diets based on cottonseed meal. Six experimental diets were created, each containing 200 mgkg-1 of enzyme supplements. The diets consisted of a control diet (CON) without enzyme supplements and five treatment diets: four single-enzyme supplements, namely phytase (PHY), xylanase (XYL), protease (PRO), and cellulase (CEL), and a fifth treatment diet containing a mixture (MIX) of all four enzyme supplements. Fingerlings (7.74 ± 0.30geach) were introduced into V-shaped water tanks that were intended to hold waste. For seventy days, fish in three replicate tanks received feed at a rate of five percent of their live body weight. The results indicated that the MIX yielded the most favorable outcomes, followed by PHY, XYL, and CEL, while PRO and CON group showed negligible differences. Notably, the MIX supplementation resulted in maximum specific growth rate, weight gain percentage, and minimum feed conversion ratio, surpassing the CON group. Furthermore, the MIX at 200 mgkg-1 demonstrated optimal digestibility and carcass composition in C. catla. Additionally, the activity ofantioxidant enzymes, including superoxide dismutase, peroxidase, and catalase, exhibited enhanced performance in response to exogenous MIX enzyme supplementation. Therefore, these findings suggest that an enzyme MIX group supplemented at 200 mgkg-1, is optimal for promoting growth, nutrient digestibility, carcass composition, and antioxidant enzyme activity in C. catla.

Abstract Quillaja saponin (QS) is a substitute for antibiotics which is obtained from the wood and bark of the soap tree and contains a triterpenoid structural component. It has been demonstrated that QS can increase productivity, boost the immune system, promote intestinal health, and improve meat quality in monogastric animals without changing production costs. On the other hand, phytase (PHY), an enzyme that catalyzes the release of phosphorus from phytate has been used in swine diet for many decades. To date, there are no studies on the analysis of the comparative effect of QS and PHY supplementation in swine. Therefore, this study aimed to examine the comparative effects of low doses of QS and/or PHY on growth performance, nutrient digestibility, fecal gas emissions, and carcass grade in growing-finishing pigs. A total of 72 [(Landrace×Yorkshire) ×Duroc] pigs [initial body weight (BW) = 25.82 ± 1.68kg] were selected and randomly allocated to 3 dietary treatments with 6 replicates of 4 pigs/pen for 110 d. The test treatments were CON-basal diet, and the basal diet supplemented with 0.02% of PHY and 0.01% of QS. Experimental data were analyzed using GLM procedure of SAS and the difference between the treatments was determined using contrast. P &amp;lt; 0.05 denotes significance. During the overall experimental period pigs fed a diet supplemented with 0.01% QS supplement showed increased (P &amp;lt; 0.05) BW, daily feed intake (ADFI), and reduced (P &amp;lt; 0.05) gain to feed ratio (G: F) compared with those fed CON and PHY. While pigs fed a diet supplemented with 0.02% PHY had only improved (P &amp;lt; 0.05) average daily gain (ADG) with no adverse effect on BW, ADFI, and G:F. The results of nutrient digestibility, fecal gas emission, and carcass grade were similar between the test treatments, and no significant effects were found until d 110. In conclusion, instead of adding 0.02% of PHY, adding 0.01% of QS to growing-finishing pig diets would be more beneficial to enhance their growth rate.

This experiment aimed to evaluate the effects of low doses of Quillaja saponin (QS) or phytase (PHY) on growth performance, nutrient digestibility, faecal gas emissions, and carcass grade in growing-finishing pigs. A total of 72 pigs (Landrace × Yorkshire × Duroc), each weighing 25.82 ± 1.68 kg, were selected and randomly assigned to three treatment groups. Each group had six replicates, with four pigs per pen, and the allocation was based on the four initial body weight and sex of the pigs. They were randomly divided into the following three diet groups: the basal diet as a control (CON) group, the basal diet + 0.02% PHY; and the basal diet + 0.01% QS. The experiment period lasted for 110 days. The results of adding 0.01% QS to the basal diet of pigs show that it can significantly increase the body weight (BW) of growing-finishing pigs on the 110th day (p < 0.05). QS can significantly increase the average daily weight gain (ADG) on Days 80-110 of the experiment (p < 0.05). QS can significantly increase the total average daily weight gain (TADG) of growing-finishing pigs during the entire experimental period (p < 0.05) and has a tendency to improve the average daily feed intake and feed conversion rate during the entire experimental period. However, QS has no significant effect on pig nutrient digestibility and carcass grade. In addition, we also found that QS has a tendency to reduce carbon dioxide emissions. However, adding 0.02% PHY to the basal diet of growing-finishing pigs can only increase the TADG during the entire experimental period. Throughout the experiment, adding PHY to the diet had no significant impact on the nutrient digestibility, faecal gas emissions, and carcass grade of growing-finishing pigs. In summary, adding QS to feed can significantly improve the growth performance of growing-finishing pigs, and has a tendency to improve faecal gas emissions. PHY can only improve the growth performance of growing-finishing pigs.

The purpose of this study was to analyze how the mineral digestibility of Cirrhinus mrigala was improved by the replacement of canola meal (CM) along with the supplementation of citric acid (CA) and phytase (PHY). A 90-day feeding trial was conducted in a completely randomized design. Sixteen test diets were formulated with different concentrations of CM (0%, 25%, 50%, and 75%), in the basal diet. Each concentration level was supplemented with four doses, one without supplementation, second with 2.5% CA, third with 750 FTUkg-1 PHY and fourth with combined supplementation (CA + PHY) to form sixteen test diets (T1-T16). Fifteen fingerlings (N = 720) were kept in each tank in triplicate. At the end of the trial, it was revealed that as the amount of CM in the diets increased, there was a significant (P≤0.05) increase in mineral digestibility (Fe, Ca, Mg, K, Mn, Cu, P, Na, Cr, Zn and Al). The fish that consumed 50% CM-based diet supplemented with 2.5% CA and 750 FTUkg-1 PHY had the maximum apparent digestibility coefficient of minerals (K 73.76%, Ca 64.79%, Na 62.56%, P 73.11%, Cu 76.52%, Fe 77.14%, Mn 71.87%, Mg 71.42%). The results of this research suggest that supplementing a diet high in CM (50%) with 2.5 percent CA and 750 FTUkg-1 PHY is the most effective strategy to increase the digestibility of minerals in C. mrigala fingerlings. Keywords: Fish meal, substitution, aquaculture, plant meal, acidified phytase

Ileal mineral digestibility and expression of nutrient transporter genes of broiler chickens in response to variable dietary total Ca and phytase supplementation are influenced by time on experimental diet and age of the birds

A series of four broiler performance studies were conducted in different facilities to investigate the efficacy of a novel bacterial 6-phytase added at 500 FTU/kg diet on growth performance, bone mineralization and precaecal digestibility of phosphorus (pcdP) in broilers fed diets deficient in available P (avP) and calcium (Ca). The experimental design was the same for all studies, with each having three treatments: positive control (PC) diet formulated to meet or exceed the requirements of birds, negative control (NC) diet similarly reduced by 0.15% points in avP and Ca compared to the PC diet, and the NC diet supplemented with phytase (PHY) at 500 FTU/kg diet from 1 to 35 days of age. Body weight (BW) and feed intake were measured at 21 and 35 days of age, and average daily gain (ADG), average daily feed intake (ADFI), feed conversion ratio (FCR), BW gain-corrected-FCR (cFCR), mortality and European performance efficiency factor (EPEF) were calculated. Tibia dry matter, tibia ash content and pcd of P were measured at 21 days of age in all experiments. The analysis of the data from the four experiments showed that compared with birds fed the adequate-nutrient diet, birds fed the NC diet resulted in a decrease (p &lt; 0.05) in BW, ADG, ADFI and EPEF by 6.4, 6.3, 5.9 and 7.1%, respectively, and an increase in (p = 0.02) cFCR by 2.0%. The tibia dry matter and tibia ash content of these birds were also reduced (p &lt; 0.001) by 3.8 and 4.0% points, respectively. PHY diets improved (p &lt; 0.05) BW, ADG, ADFI, EPEF and cFCR by 8.0, 8.3, 7.3, 10.6 and 2.8%, respectively. Phytase addition at 500 FTU/kg diet also increased (p &lt; 0.001) the tibia dry matter and tibia ash content by 3.5 and 4.2% points, respectively. The pcd of P was improved (p &lt; 0.001) by 11.1 and 11.3% points, in comparison with NC and PC diets, respectively, when phytase was added. These performance parameters and tibia mineralization obtained with a diet supplemented with phytase were comparable to or better than the PC diet. The results demonstrated that avP and Ca could be lowered similarly by 0.15% points in broilers diets by using the new bacterial 6-phytase at 500 FTU/kg diet.

Given the ban on antibiotic growth promoters, the effects of nonantibiotic alternative growth promoter combinations (NAGPCs) on the growth performance, nutrient utilization, digestive enzyme activity, intestinal morphology, and cecal microflora of broilers were evaluated. All birds were fed pellets of two basal diets—starter (0–21 d) and grower (22–42 d)—with either enramycin (ENR) or NAGPC supplemented. 1) control + ENR; 2) control diet (CON, basal diet); 3) control + mannose oligosaccharide (MOS) + mannanase (MAN) + sodium butyrate (SB) (MMS); 4) control + MOS + MAN + Bacillus subtilis (BS) (MMB); 5) control + MOS + fruit oligosaccharide (FOS) + SB (MFS); 6) control + FOS + BS (MFB); 7) control + MOS + FOS + MAN (MFM); 8) control + MOS + BS + phytase (PT) (MBP). ENR, MOS, FOS, SB, MAN, PT, and BS were added at 100, 2,000, 9,000, 1,500, 300, 37, and 500 mg/kg, respectively. The experiment used a completely random block design with six replicates per group: 2400 Ross 308 broilers in the starter phase and 768 in the grower phase. All NAGPCs significantly improved body weight gain (P < 0.01), utilization of dry matter, organic matter, and crude protein (P < 0.05), villus height and villus height/crypt depth in the jejunum and ileum (P < 0.01), and decreased the feed conversion ratio (P < 0.01) at d 21 and 42. MMS, MMB, MFB, and MFM duodenum trypsin, lipase, and amylase activities increased significantly (P < 0.05) at d 21 and 42. On d 21 and 42, MMS, MMB, and MBP increased the abundance of Firmicutes and Bacteroides whereas MMB, MFB, and MBP decreased the abundance of Proteobacteria, compared to ENR and CON. Overall, the NAGPCs were found to have some beneficial effects and may be used as effective antibiotic replacements in broilers.

Phosphatases play important roles in converting organic phosphorus into inorganic phosphorus in soil. However, studies from this perspective on the water-level-fluctuation zone (WLFZ) of the Three Gorges Reservoir are limited. In this study, phosphatase activity and the forms of phosphorus were analyzed. Soil samples were collected in the river basin of the Penxi River in the WLFZ during a drying period. The correlation between phosphatase activity and phosphorus forms and the impacts of phosphatase activity on the phosphorus forms were analyzed. The results showed that the contents of H2O-Pi, NaHCO3-Pi, and NaOH-Pi in the soils of the WLFZ were higher than those in the soils by the river. In addition, a higher altitude resulted in higher contents of bio-enzymatically hydrolysable phosphorus and NaOH-Po. Furthermore, redundancy analysis (RDA) showed that the contents of organic matter and amorphous Fe and Mn were the main factors affecting soil organic phosphorus forms. The average activities of acid phosphomonoesterase (ACP), alkaline phosphomonoesterase (ALP), phosphodiesterase (PDE) (all in p-NP), and phytase (PAE) (in P) in the soils of the WLFZ were 1.40, 2.60, 0.44, and 11.43 μmol·(g·h)-1, respectively. Moreover, the activities of different phosphatases increased with altitude. Soil plant biomass and microbial biomass were important reasons for the difference in spatial distribution of phosphatase activity in the soil of the WLFZ. Phosphatase activities were significantly positively correlated with the contents of organic phosphorus forms but negatively correlated with the content of bioavailable phosphorus. A higher soil phosphatase activity and a lower content of bioavailable phosphorus were usually detected in soil samples taken at a higher altitude. In the early stage of flooding, phosphatase converted organic phosphorus into inorganic phosphorus at a relatively high rate, and the risk of phosphorus release to the overlying water body was also high. This study contributed to a comprehensive understanding of the geochemical cycle of soil phosphorus in the soil of the WLFZ.

Simple SummarySkeletal disorders and related-welfare complications are an ongoing concern for rapid-growing broiler chickens. Phosphorus is a vital nutrient in the poultry diet, and it is related to bone growth and skeleton rigidity and strength. Poultry utilize approximately 60% of the dietary P, and the residual is excreted and may enter the environment leading to environmental pollution. Consequently, a better understanding of intestinal phosphorus absorption will enable augmenting phosphorus utilization and reducing phosphorus excretion and feed costs in the poultry industry. Therefore, the present trial was designed to assess various supplements on performance, nutrient digestibility, bone physical parameters and mineralization, blood constituents, bone and gut histomorphology, and duodenal phosphorus transporter genes of broiler chickens fed a decreased non-phytate phosphorus. The dietary addition of phytase or probiotic to a low phosphorus diet was beneficial with respect to growth performance and carcass traits. Regarding nutrient digestibility, tibia quality parameters, and gut and bone histomorphology, all three dietary supplements (probiotics, yeast, and fumaric acid) were advantageous, and these improvements were of comparable magnitude to those of the positive control and phytase groups. The up-regulation of duodenal NaP-IIb and PiT-2 genes in the supplemented groups may suggest greater phosphorus availability. It can be concluded that these supplements were beneficial in mitigating the negative effects of phosphorus reduction on the growth performance, health, and bone quality of broilers.The present trial was designed to assess the effect of phytase, multi-strain probiotic, Saccharomyces cerevisiae, and fumaric acid on performance, nutrient digestibility, bone physical parameters and mineralization, blood constituents, bone and gut histomorphology, and duodenal phosphorus transporter genes of broiler chickens fed a decreased non-phytate phosphorus (nPP) diet for 5 weeks. A total of 480 broiler chickens were allotted to six dietary groups and eight replicates each: (1) positive control diet with recommended levels of nPP (PC; 0.48, 0.44, and 0.41% in the three feeding phases); (2) negative control diet with a decreased dietary nPP (NC; 0.28, 0.24, and 0.21% in the three feeding phases); (3) NC + 600 FTU/kg phytase (PHY); (4) NC + 0.05% multi-strain probiotic (PRO); (5) NC + 0.2% Saccharomyces cerevisiae (SC); and (6) NC + 0.2% fumaric acid. Growth performance data were recorded weekly, and blood sampling was performed at days 21 and 35 of age. Bone quality traits, gut and tibia histology, nutrient digestibility, and intestinal gene expression analyses were conducted at the end of the trial (35 days of age). Final body weight and total gain at day 35 of age of the broiler chickens fed with the PHY, PRO, and SC diets were greater (p < 0.01) than in NC, where broilers fed with the PRO and PHY diets had higher values and were similar to that of PC. There was a non-significant variation in the cumulative feed intake among the treatment groups. The PHY and PRO groups had better FCR than the PC group (p < 0.05), and FA and SC had an FCR equivalent to that of PC. The PHY and PRO broilers had greater dressing % than the NC group (p < 0.05) and even better than PC. The PHY, PRO, SC, and FA broilers had higher relative weights of spleen and bursa of Fabricius (p < 0.01) than NC. In comparison to NC, the PHY, PRO, and SC groups improved (p < 0.05) CP, CF, Ca, and P digestibility. Greater tibia breaking strength of the low nPP-supplemented groups was shown to be associated with higher tibia ash, Ca, and P concentrations (p < 0.01) and increased (p < 0.001) tibia cortical area thickness. At days 21 and 35 of age, the dietary supplements to low nPP diets reduced (p < 0.05) serum total cholesterol, triglyceride, triiodothyronine, thyroxine, glucose, and alkaline phosphatase levels, while serum Ca and P concentrations were improved (p < 0.05) compared to NC. All supplements led to enhancement (p < 0.01) in villi height and width and villi absorptive surface area when compared with NC and were even comparable to that of PC. The mRNA expression of NaP-IIb was up-regulated (p < 0.001) in the duodenum of PRO and FA broilers at day 35 of age compared with NC, and their expression levels were similar to that of PC, indicating greater P availability. It is concluded that dietary supplementation of PHY, PRO, SC, and FA to a low nPP diet was advantageous and mitigated the negative impacts of P reduction on the growth performance, health, nutrient digestibility, and bone quality of broilers.

Straw retention combined with phosphorus fertilizer promotes soil phosphorus availability by enhancing soil P-related enzymes and the abundance of phoC and phoD genes