Nonphytate P Research Articles

The relationship between phosphorus retention and fibroblast growth factor 23 in broiler breeders

Previous studies with broiler breeders indicate a P retention threshold when fed daily dietary levels of non-phytate P (NPP) exceeding 320 mg. Fibroblast growth factor 23 (FGF23) is a hormone secreted by osteocytes which modulates P retention and could be the biological agent which controls the P threshold in breeders. To evaluate the relationship between FGF23 and the P retention threshold, a 4-wk study with 32-wk old breeders was conducted with 6 dietary treatments with daily NPP intake of 216 to 576 mg/d/h with increments of 80 mg/kg diet. The goals were 1) to elucidate how plasma FGF23 corresponds with the P retention threshold in broiler breeders and 2) to determine the amount of P for optimal egg production and bone health. Results showed that between daily 288 mg and 360 mg dietary NPP intake, P retention decreased from 33% to 26% but FGF23 levels increased from 130 pg/mL to 220 pg/mL with increasing NPP. The elevation of plasma FGF23 between the range of 288 mg to 360 mg dietary NPP/d intake suggests that FGF23 is related to the P retention threshold and may be the major hormone for regulating physiological P levels when intake of daily dietary P levels are increased above 288 mg NPP.

Dietary calcium and nonphosphate phosphorus interaction influences tibiotarsus development and related gene expression of broilers from 1 to 21 days of age

The dietary needs of calcium (Ca) and phosphorus (P) are interdependent, thus accurate evaluation of Ca and P requirements of broilers to support skeleton health and optimal growth is critical. The present study was carried out to investigate the effects of dietary Ca and nonphytate P (NPP) levels and their interactions on growth performance, tibiotarsus characteristics, tibiotarsus metabolism-related enzyme and proteins, and their gene expression of broilers, so as to provide a rational recommendation for Ca and NPP levels in diet. A total of 540 one-day-old Arbor Acres male broilers were randomly allotted to 1 of 15 treatments with 6 replicate cages of 6 birds per cage for each treatment in a completely randomized design involving a 5×3 factorial arrangement of treatments (5 levels of Ca×3 levels of NPP). The birds were fed the corn-soybean meal diet containing 0.60%, 0.70%, 0.80%, 0.90%, or 1.00% Ca and 0.35%, 0.40%, or 0.45% NPP for 21 d. Dietary Ca level affected (P < 0.03) the bone mineral density, bone mineral content (BMC), breaking strength, ash percentage and ash Ca contents in tibia, which showed linear (P < 0.006) responses to dietary Ca levels. Dietary NPP level affected (P < 0.05) tibia BMC, ash percentage, and FGF23 mRNA level. Broilers that received 0.40% and 0.45% NPP had higher (P < 0.04) tibia BMC and ash percentage than those that received 0.35% NPP, but no differences (P > 0.05) were found between 0.40% and 0.45% NPP. Broilers that received 0.40% NPP had higher (P=0.02) tibia FGF23 mRNA level than those that received 0.35% NPP, but no differences (P > 0.05) were detected between 0.40% and 0.45% NPP or 0.45% and 0.35% NPP. The interactions between dietary Ca and NPP affected (P < 0.05) ADG, ALP activity, bone gal protein, FGF23 contents, and the mRNA expression levels ALP and bone gal protein in tibia of broilers. Results from the present study indicate that dietary Ca and NPP interaction influences growth, tibiotarsus development, and related gene expression of broiler chickens. Considering all the criteria, the dietary levels of 0.90% Ca and 0.45% NPP would be optimal for both growth and tibiotarsus development of broilers fed a conventional corn-soybean meal diet from 1 to 21 d of age.

Interactive effects of calcium, vitamin D3, and exogenous phytase on phosphorus utilization in male broiler chickens from 1 to 21 days post-hatch: A meta-analysis approach

Provision of appropriate dietary phosphorus (P) content considering environmental and economic aspects has been challenging for poultry nutritionists during the last decades. For this reason, many studies have focused on factors affecting P utilization in broiler chickens, such as calcium (Ca), cholecalciferol (vitamin D3; VD), and exogenous phytase (EP), but their results have sometimes been accompanied by inconsistencies. Therefore, comprehensive knowledge of the factors affecting P utilization and their interactions is required to draw conclusions from the available results. For this purpose, a meta-analysis was conducted using 79 studies including 719 experimental treatments published between 2011 and 2021, which considered the effects of Ca, EP, and VD on P utilization in male broiler chickens from 1 to 21 days post-hatch. The collected data were fitted well to a mixed model for average daily gain (ADG; R2 = 0.941), average daily feed intake (ADFI; R2 = 0.956), feed conversion ratio (FCR; R2 = 0.989), and tibia ash (TA) content (R2 = 0.984). Linear and quadratic effects of dietary non-phytate P (NPP) content on ADG, ADFI, FCR, and TA content were observed (P < 0.001). Also, results showed the linear and quadratic effects of EP on ADG, FCR, and TA content (P < 0.001). The ADG (P < 0.01) and TA content (P < 0.05) were affected by VD supplementation. The fitted models showed that the increase in dietary Ca content linearly exacerbated all responses (P < 0.001), but such negative effects were alleviated with the increase in dietary NPP content and EP and, or VD addition due to their interactions. Results of the optimization process showed that simultaneous addition of EP and VD resulted in lower NPP concentration required to optimize growth performance and TA content compared to separate supplementation. Also, increasing dietary level of EP (up to 2000 FTU/kg of diet) reduced NPP requirement for optimal growth performance and bone mineralization. It can be concluded that Ca, EP, and VD affect the NPP requirements of broiler chickens, but the magnitude of these effects varies depending on the studied criterion.

Effects of Dietary Phosphorus Deficiency and High Phosphorus Content on the Growth Performance, Serum Variables, and Tibia Development in Goslings

Understanding how dietary phosphorus (P) regulates the growth and skeletal development of goslings is essential for fully utilizing P in the production of geese. We aimed to study the effects of dietary P deficiency and high P content on growth performance, serum variables, tibia quality, and mRNA expression of osteogenesis-related genes in tibia to reveal how dietary P regulates bone development in goslings. Two hundred and sixteen one-day-old Jiangnan White male geese were fed corn-soybean meal diets for 14 days. The diets were set with the same calcium (Ca) level (0.80%) and three non-phytate P (NPP) levels: 0.08% (P deficiency), 0.38% (P control), and 0.80% (P high content). Each treatment consisted of six replicates with 12 goslings in each replicate. The P deficient group had a high cumulative mortality of 26.67% with lower body weight (BW), average daily feed intake (ADFI), average daily gain (ADG), serum P contents, tibia width, tibia length, tibia fresh weight at d 14 as compared with the control and high P content group (p ≤ 0.05). Dietary P deficiency caused a reduction in the goslings’ tibia strength, tibia ash content, tibia Ca content, and tibia P content during d 4–d 14 (p &lt; 0.05). The P deficiency reduced tibia mRNA expression of osteoprotegerin (OPG) and runt-related transcription factor 2 (Runx2) on d 7 (p &lt; 0.05), whereas up-regulated serum alkaline phosphatase (ALP) activity, calcitonin (CT) content, and the tibia mRNA ratio of receptor activator of NF-κB ligand (RNAKL)/OPG during d 7–d 14 (p &lt; 0.05). The serum 1,25-(OH2)D3 content, serum bone Gla-protein (BGP), and the mRNA relative expression of RNAKL and BGP in tibia were decreased in the NPP 0.08% and 0.80% groups compared with the control on d 14 (p &lt; 0.05). In conclusion, dietary P deficiency induced acute rickets in goslings as early as the fourth day. A P deficiency hindered the tibia and body growth partly due to poor skeletal calcification caused by a down-expression of osteogenesis-related genes regulated by high serum ALP activity and calcitonin contents and lower serum BGP and skeletal P contents.

Evaluation of the efficacy of a novel phytase in short-term digestibility and long-term egg production studies with laying hens

Three independent trials were conducted to evaluate the efficacy of a novel phytase in laying hens. Trial 1 used a total of 90 laying hens (Lohmann Brown, 33-wk-old) fed either a negative control (NC) diet with 0.09% non-phytate P (NPP) or NC supplemented with 187.5 or 375 FYT phytase/kg feed for 4 d before collection of excreta and ileal digesta to measure ileal digestibility and retention of Ca and P. In trial 2 and 3, a total of 108 laying hens (Hy Line Brown, 25-wk-old) and 360 hens (Lohman Brown, 25-wk-old) were used, respectively. In both trials, the hens were randomly assigned to 3 dietary treatments: NC with 0.1% NPP, positive control (PC) and NC plus 187.5 FYT phytase/kg feed, the experimental diets were fed for 12 wk, and egg production and bone mineralization were measured. The results showed that the ileal digestibility of P increased both linearly (P = 0.012) and quadratically (P = 0.01) with increasing supplementation of phytase in trial 1. In trial 2, phytase supplementation significantly improved egg production, egg weight, and feed conversion ratio and reduced the percentage of broken eggs during the overall trial duration compared with NC. In trial 3, phytase significantly improved egg production, egg weight, and feed intake and reduced the percentage of broken eggs during the entire trial duration. In addition, percentage and weight of bone Ca and P increased significantly with added phytase. In trial 2 and 3, there was no significant difference between PC and the phytase treatment. In conclusion, the novel phytase significantly increased the ileal digestibility of P in a short-term digestibility study and improved egg production and bone mineralization in a 12-wk laying cycle. Ileal digestibility of P rather than P retention in short-term digestibility studies as well as egg production and whole tibia mineralization in long-term studies should be measured to demonstrate the efficacy of phytase in laying hens.

Effects of phytase supplementation on production performance, egg and bone quality, plasma biochemistry and mineral excretion of layers fed varying levels of phosphorus

Excessive fecal excretion of phosphorus (P) has increasingly become an environmental issue due to oversupply of P in layer rations, and thus it is imperative to minimize safety margins for P to ensure the sustainability of the egg industry. In this study, a 12-week feeding trial (22 to 34 weeks of age) was conducted to evaluate the effects of phytase supplementation on production performance, plasma biochemistry, egg and bone quality and P excretion of laying hens fed various levels of non-phytate P (NPP). Forty-eight Lohmann white laying hens were randomly allocated to one of six corn–soybean meal–oat-based diets: diets containing 2.0, 2.5 or 3.0 g/kg NPP without phytase, and diets containing 1.0, 1.5 or 2.0 g/kg NPP with phytase (1 000 U/kg diet) where phytase inclusion was expected to provide 1.0 g/kg NPP to laying hens, thus making the phytase-unsupplemented treatment served as a control for the phytase-supplemented treatment accordingly. Productive performance was recorded during the experimental period. Blood and egg samples were collected, and digestibility studies were conducted at weeks 6 and 12 of the experiment. Bone mineralization was evaluated at the end of the experiment. Egg weight and egg production, feed consumption, BW and feed conversion ratio of laying hens fed lower NPP diets supplemented with phytase were comparable to those of hens fed high NPP phytase-unsupplemented controls. Eggshell thickness, specific gravity, Haugh units, tibia bone mineral density, tibia ash percent, plasma P and other biochemical parameters were not significantly different among dietary treatments. Total P intake, excretion and retention were affected by diet (P < 0.001), but its deposition in eggs was not significantly different. Contrast analysis further showed that total P excretion of phytase present vs phytase absent was averagely reduced by 40.4 mg/hen per day (P < 0.01). Moreover, total P excretion was linearly (P < 0.01) reduced with lowering dietary NPP, and this relationship was similar regardless of whether phytase was supplemented or not. The results from this study indicated that NPP levels in laying hen diets could be reduced to 1.0 g/kg (excluding the portion of NPP released by phytase) with the inclusion of phytase, without negative effects on production performance and health of the hens, thereby diminishing P excretion into environment.

Effect of sequential feeding of phosphorus-deficient diets and high-dose phytase on efficient phosphorus utilization in broiler chickens

ABSTRACT An experiment was conducted to investigate the effectiveness of sequential feeding of a very low non-phytate P (NPP) diet supplemented with varying doses of phytase to broiler chickens. A total of 450 one-day-old male broiler chickens were fed a standard diet up to 14 d of age, then allotted to 6 dietary treatments (with 5 replicates of 15 broiler chickens each) from d 14 to 42. Dietary treatments included a positive control [PC; 4.35 g NPP/kg (d 14 to 28) and 3.95 g NPP/kg (d 28 to 42)], a negative control without any inorganic P source [NC; 1.50 g NPP/kg (d 14 to 28) and 1.36 g NPP/kg (d 28 to 42)], and a negative-positive control (NPC), in which broiler chickens received the PC for 24 h and then fed the NC (including 0, 500, 1,500, or 3,000 FTU phytase/kg) for the following day in a 48-h-cycle sequential feeding program. The Ca to NPP ratio was maintained at 2 to 1 in all formulations. The NC diet decreased overall feed intake (FI) and serum P compared to those of the PC diet (P = 0.047 for overall FI; P

Effect of dietary calcium or phosphorus deficiency on bone development and related calcium or phosphorus metabolic utilization parameters of broilers from 22 to 42 days of age

This experiment was conducted to investigate the effect of dietary calcium (Ca) or phosphorus (P) deficiency on bone development and related Ca or P metabolic utilization parameters of broilers from 22 to 42 days of age based on our previous study, which indicated that dietary Ca or P deficiency impaired the bone development by regulating related Ca or P metabolic utilization parameters of broilers from 1 to 21 days of age. A total of 504 one-day-old Arbor Acres male broilers were randomly assigned to 1 of 4 treatments with 7 replicates in a completely randomized design, and fed the normal control and Ca- or P-deficient diets from 1 to 21 days of age. At 22 days of age, the broilers were further fed the normal control diet (0.90% Ca+0.35% non-phytate P (NPP)), the P-deficient diet (0.90% Ca+0.18% NPP), the Ca-deficient diet (0.30% Ca+0.35% NPP) or the Ca and P-deficient diet (0.30% Ca+0.18% NPP), respectively. The results showed that dietary Ca or P deficiency decreased (P<0.05) tibia bone mineral density (BMD), bone breaking strength (BBS), ash content, tibia ash Ca content and serum P content on days 28 and 42, but increased (P<0.05) tibia alkaline phosphatase (ALP) activity of broilers on day 42 compared with the control group. Furthermore, the broilers fed the P-deficient diet had the lowest (P<0.05) tibia BMD, BBS, ash content, serum P content and the highest (P<0.05) serum Ca content on day 28 compared with those fed the Ca-deficient or Ca and P-deficient diets. The results from the present study indicated that the bone development and related Ca or P metabolic utilization parameters of broilers were the most sensitive to dietary P deficiency, followed by dietary Ca deficiency or Ca and P-deficiency; dietary Ca or P deficiency impaired the bone development possibly by regulating serum Ca and P contents as well as tibia Ca content and ALP activity of broilers from 22 to 42 days of age.

Egg Shell Quality and Bone Status as Affected by Environmental Temperature, Ca and Non-Phytate P Intake and in vitro Limestone Solubility in Single-Comb White Leghorn Hens

Environmental temperature (ET) often changes the nutrient intake/output for layers. Changing feed formulations based on ET may need to be utilized to obtain optimum performance, shell quality and bone status. This study was conducted to investigate the effects of temperature, Ca intake, non-phytate P (NPP) intake and in vitro limestone solubility (LS) on egg-shell quality and bone status in commercial White Leghorn hens. Egg mass and shell weight per unit surface area (SWUSA) decreased with increasing ET (p lower than 0.05), especially when ET was 29.7 C (cycling mean ET)or a constant ET was 32.2 C. Feeding layers a low soluble larger particle size limestone instead of a highly soluble limestone produced beneficial effects for SWUSA at the thermoneutral ET (21.1 C) but the beneficial effect was less or disappeared when ET was higher than 26.6 C in EXP 1 and 2. Feeding layers 245 and 353 mg NPP/h/d supported satisfactory bone status at 21.1 C, however layers housed at higher than 30 C needed an additional intake of 50 mg NPP/h/d to support bone integrity. Results of EXP 1 and 2 indicates that 48 week old layers housed in thermoneutral or warmer ET require a minimum of 4.2 g Ca/h/d for maintaining optimum shell quality and bone integrity. Feeding low LS (34.1% in vitro solubility) improved egg shell quality only for hens housed in thermoneutral ET (21.1 C) and did not improve egg shell quality at higher ET (constant or cycling). Daily NPP intake of 245 and 353 mg/h/d supported optimum egg production and bone status at 21.1 C, respectively. A higher NPP and Ca intake may be required for bone status compared to egg production, especially in older hens.

Modelling and optimizing of calcium and non-phytate phosphorus requirements of male broiler chickens from 1 to 21 days of age using response surface methodology

The skeleton is the main site of P and Ca deposition; therefore, accurate estimation of Ca and P requirements is necessary to maintaining health and optimum performance of broiler chickens. A response surface methodology (RSM) using a central composite design (CCD) was used for evaluating and optimizing of Ca and non-phytate P (NPP) requirements of broiler chickens for optimal performance, ileal nutrient digestibility and bone mineralization from 1 to 21 days of age. A total of 750 one-day-old male broiler chickens (Ross 308) were randomly distributed into 50 cages including 9 treatments, each replicated 5 times (except central treatment with 10 replicates) and 15 birds in each cage by CCD. The dietary Ca levels of 4.3, 5.6, 8.6, 11.7 and 13.0 g/kg and NPP of 2.5, 2.9, 4.0, 5.0 and 5.4 g/kg were used for nine treatments of CCD. The results indicated that the linear and quadratic effects of NPP, quadratic effects of Ca and Ca × NPP were significant for average weight gain (AWG, P < 0.05), average feed intake (AFI, P < 0.05), feed conversion ratio (FCR, P < 0.05) and Ca and P apparent ileal digestibility (AID, P < 0.05); however, the linear effect of Ca was significant only for FCR (P < 0.05). On the other hand, tibia and toe ash were affected by NPP (linear and quadratic, P < 0.01) and Ca (quadratic, P < 0.01). The second-order polynomial regression model was significant for AWG (R2 = 0.93, P < 0.001), AFI (R2 = 0.88, P < 0.001), FCR (R2 = 0.78, P < 0.001), AID of Ca (R2 = 0.78, P < 0.001) and P (R2 = 0.88, P < 0.001), tibia ash (R2 = 0.86, P < 0.001) and toe ash (R2 = 0.85, P < 0.001). The multi-objective optimization indicated that broiler chickens from 1 to 21 days of age need 7.03 and 4.47 g/kg of Ca and NPP, respectively, to achieve optimal AWG, FCR, tibia and toe ash. However, the dietary Ca and NPP levels can be reduced to 6.57 and 3.95 g/kg with a slight negative impact on performance and bone mineralization, respectively. In conclusion, the findings indicate that using multi-objective optimization model such as RSM provides more information regarding optimum Ca and NPP requirements of broiler chickens, considering the complex interaction between these two minerals. While the NPP levels are in line with current recommended requirements, Ca levels are considerably lower and suggest that current recommended Ca requirements may be in excess of the needs of the broiler.

Dietary supplemental vitamin D3 enhances phosphorus absorption and utilisation by regulating gene expression of related phosphate transporters in the small intestine of broilers.

The present study was carried out to evaluate the effect of dietary supplemental vitamin D3 (VD3) on P absorption and utilisation as well as its related mechanisms in the small intestine of broilers. A total of 384 1-d-old Arbor Acres male broilers were assigned randomly into four treatments following a completely randomised design with a 2 (dietary non-phytate P (NPP) contents: 0·43 and 0·22 %)×2 (dietary VD3 supplemental levels: 0 and 87·5 μg/kg) factorial arrangement. The experiment lasted for 22 d. The results showed that P contents in serum from the hepatic portal vein and tibia ash of broilers were higher (P&lt;0·05) for 0·43 % NPP than for 0·22 % NPP. The type IIb Na-dependent phosphate cotransporter (NaP-IIb) protein expressions in the duodenum and ileum were higher (P&lt;0·05) also for 0·43 % NPP than 0·22 % NPP. Supplementation of VD3 enhanced (P&lt;0·05) tibia P retention rate and type III Na-dependent phosphate cotransporter (PiT)-1 protein expression in the duodenum of all broilers. Moreover, VD3 supplementation decreased (P&lt;0·002) mortality and increased (P&lt;0·02) serum P content from the hepatic portal vein after 4 h of feeding, tibia ash content, tibia ash P content and protein expressions of NaP-IIb and PiT-1 in the jejunum of broilers fed diet with 0·22 % NPP. Thus, dietary supplemental VD3 promoted intestinal P absorption and bone P utilisation, and this effect might be associated with enhanced PiT-1 levels in the duodenum and PiT-1 and NaP-IIb levels in the jejunum respectively when dietary NPP is limiting.

The effects ofmicrobial phytases and dietary calcium and phosphorus levels on the productive performance and bone mineralization of broilers

Two trials were conducted to evaluate the effects of phytase and different levels of calcium (Ca) in an available phosphorus-limited diet (aP) on the performance, bone mineralization, and Ca and P retention of broilers. In Trial 1, 160 one-day-old male broilers were placed into 40 cages and allocated to five dietary treatments: one positive control [PC, 4.7 and 4.3 g/kg non-phytate P (NPP) and 9.0 and 8.5 g/kg Ca, from 1 to 21 days (d) and from 21 to 35 d of age, respectively] and four negative control [NC, 3.2 and 2.9 g/kg NPP and 7.0 and 6.3 g/kg Ca in starter (1–21 d) and growth (22–35 d) diet] groups comprising 4 concentrations of phytase A (FLF® 1000 FUT, 0, 250, 500 and 1000 FTU/kg). In Trial 2, 300 one-day-old broilers were placed into 60 cages and allocated to 10 dietary treatments, consisting of two NC diets (3.2 g/kg NPP), either 7.0 g/kg Ca (low Ca) or 9.0 g/kg Ca (high Ca), supplemented (0 or 500 FTU/kg) with four different phytases [OptiPhos® 5000 CT (A), Phyzyme® XP10000 TPT (B), Ronozyme® NP (C) and FLF® 1000 FUT (D)] from 1 to 14 d. In Trial 1, the PC group and the group receiving the highest dose of phytase A FLF® 1000 FUT (1000 FTU/kg) yielded significantly higher average daily gains from 1 to 21 d and higher tibia weights and ash contents than the NC, 250, and 500 FTU/kg. In Trial 2, no differences were observed in performances between animals receiving different types of phytase. Low Ca diets improved the feed efficiency from 1 to 7 d and ileal P digestibility. The interaction between Ca:aP and phytase affected (P ≤ 0.05) the feed efficiency from 1 to 7 d and ADG from 7 to 14 d. Based on this study, high levels of phytase (1000 FTU/kg) supplemented in starter (1–21 d) and growth (22–35 d) diets containing 3.2 and 2.9 g/kg NPP and 7.0 and 6.3 g/kg Ca, respectively, may be required to promote performance and bone mineralization in growing broilers. Lowering Ca levels to 7 g/kg in starting diets may exert greater effects on performance and ileal P digestibility than low levels (500 FTU/kg) of phytase.

Effect of immobilized fungal phytase on growth performance and bone traits of broilers fed with low dietary calcium and phosphorus.

Aim:The aim of this study was to investigate the effects of phytase which was laboratory produced by Aspergillus foetidus on the growth performance, mineral retention, and bone traits of broilers fed with low dietary calcium and phosphorus.Materials and Methods:The extracellular phytase enzyme secreted into the crude filtrate was concentrated by ammonium sulfate precipitation to obtain an activity of 500 phytase units (FTU). A total of 90 1-day-old chicks (Cobb 500) were randomly divided into three treatment groups with five replicates having six birds each. Dietary treatment, T1, was with 0.45% non-phytate P (NPP) during starter and 0.40% during finisher phase with 1% Ca. Dietary treatment, T2, had 0.37% NPP during starter and 0.32% in finisher phase with 1% Ca and supplemental lab phytase at 500 FTU/kg. Dietary treatment, T3, was similar to T2 with a lower Ca of 0.8%.Results:There was no significant difference among the dietary treatments with regard to body weight gain, feed intake, feed conversion ratio, and Ca retention (p>0.05). However, a significant improvement in retention of P by birds was observed in phytase supplemental groups T2 and T3 (p<0.05). Dry weight of tibia (2.58-2.78 g/kg live weight) and ash content (39.7-41.8%) was comparable among treatments. A similar trend was observed for bone Ca, P, and Mn content.Conclusion:The study indicated that 500 FTU/kg phytase can be effectively supplemented in a broiler diet with low phosphorus (0.37% in starter and 0.32% NPP in finisher diet) and low calcium (0.8% in diet) for better growth performance and with successful replacement of dietary P by 0.08 % and reduced P excretion into the environment in broiler chicken.

Phosphorus absorption and gene expression levels of related transporters in the small intestine of broilers.

To investigate the P absorption and gene expression levels of related co-transporters, type IIb sodium-dependent phosphate co-transporter (NaPi-IIb), inorganic phosphate transporter 1 (PiT-1) and inorganic phosphate transporter 2 (PiT-2) in the small intestine of broilers, 450 1-d-old Arbor Acres male broilers were randomly allocated to one of three treatments with ten replicate cages of fifteen birds per cage for each treatment in a completely randomised design. Chickens were fed a diet with no added inorganic P (containing 0·06 % non-phytate P (NPP)) or with either 0·21 or 0·44 % NPP for 21 d. Plasma P concentration in the hepatic portal vein, mRNA and protein expression levels of NaPi-IIb, PiT-1 and PiT-2 were determined at 7, 14 and 21 d of age. The results showed that the concentration of P in plasma in the hepatic portal vein increased as dietary NPP increased (P<0·0001). At 14 and 21 d of age, the increase in dietary NPP inhibited (P<0·003) NaPi-IIb mRNA expression level in the duodenum, as well as PiT-1 mRNA and protein expression levels in the ileum, but promoted NaPi-IIb protein expression level (P<0·002) and PiT-2 mRNA and protein expression levels (P<0·04) in the duodenum. These results suggest that NaPi-IIb, PiT-1 and PiT-2 might be important P transporters in the small intestine of broilers. Higher intestinal P absorption may be achieved by up-regulating the protein expression levels of NaPi-IIb and PiT-2 and down-regulating the protein expression of PiT-1.

Effect of different concentrations of dietary P and Ca on plasma inorganic P and urinary P excretion using noncolostomized and colostomized broilers

Two 5-d bioassays were conducted to explore the P physiological threshold in broilers based on plasma inorganic P (iP), urinary P and Ca, and excreta P and Ca measurements in non-colostomized and colostomized broilers fed with different concentrations of non-phytate P (NPP) and Ca. In Experiment 1, 80 40-day-old Cobb 500 non-colostomized male broilers were assorted into 8 groups consisting of 10 broilers each and placed in individual metabolic cages. Similarly, 8 colostomized broilers of same age were allotted to 8 individual metabolic cages. The experimental diets consisted of a corn soybean meal basal containing 0.17% phytate P (PP) with 8 concentrations (0.08, 0.13, 0.18, 0.23, 0.28, 0.33, 0.38, and 0.45%) of NPP. The dietary Ca concentration was maintained at 0.5% by adjusting a 185-micron particle size limestone with each concentration of added P from added calcium phosphate, dibasic, monohydrate. After Experiment 1, broilers were fed a standard grower diet for 5 d and Experiment 2 was conducted the same as Experiment 1; however, Ca was maintained at 0.9% for all test diets. Plasma iP, urinary P and Ca, and total P (TP) and Ca retention along with phytate P hydrolysis were measured. At 0.5% Ca dietary level, the inflection points for dietary NPP obtained from segmented line regression analysis for plasma iP, urinary P, and urinary Ca were 0.26% (±0.04 SE), 0.28% (±0.01 SE), and 0.30% (±0.04 SE), respectively. The similar values for 0.9% Ca diets were 0.27% (±0.03 SE), 0.21% (±0.03 SE), and 0.30% (±0.0 SE), respectively. In summary, the present findings suggest that an increased dietary NPP would increase plasma inorganic P concentration along with increased % retention of TP and NPP until the broilers reach a point of physiological steady state (7.51 mg iP/dL – 8.13 mg iP/dL as found in this study). Excess P beyond physiological threshold is eliminated in urine coupled with decreased % retention.

Adaptive response of broilers to dietary phosphorus and calcium restrictions

The aim of this study was to evaluate the capacity of chickens to adapt to and compensate for early dietary restriction of non-phytate P (NPP) and/or Ca (10 to 21 d) in a later phase (22 to 35 d), and to determine whether compensatory processes depend on the P and Ca concentrations in the finisher diet. Four diets were formulated and fed to broilers from 10 to 21 d in order to generate birds with different mineral status: L1 (0.6% Ca, 0.30% NPP), L2 (0.6% Ca, 0.45% NPP), H1 (1.0% Ca, 0.30% NPP), and H2 (1.0% Ca, 0.45% NPP). On d 22, each group was divided into three groups which received a low (L, 0.48% Ca, 0.24% NPP), moderate (M, 0.70% Ca, 0.35% NPP), or high (H, 0.90% Ca, 0.35% NPP) finisher diet until 35 d, resulting in a total of 12 treatments. Lowering the Ca level enhanced apparent ileal digestibility of P (P AID) at 21 d especially with the high NPP level (Ca × NPP, P < 0.01). The lower bone mineralization observed at 21 d in broilers fed the L1 diet compared to those fed the H2 diet had disappeared by 35 d with long-term stimulation of the P AID with the low NPP level (P < 0.001). Although P AID and growth performance were improved in birds fed the L1 L compared to the L1 H and H2 H treatments, tibia characteristics tended to be lower in birds fed the L1 L compared to those fed the L1 H treatment. Birds fed the H1 M treatment had higher P AID, growth performance and tibia ash content than those fed the H1 H treatment. A significant increase in the mRNA levels of several genes encoding Ca and P transporters was observed at 35 d in birds fed the L1 followed by the L diet compared to birds fed the L1 followed by the M diet. In conclusion, chickens are able to adapt to early dietary changes in P and Ca through improvement of digestive efficiency in a later phase, and the extent of the compensation in terms of growth performance and bone mineralization depends on the P and Ca levels in the subsequent diet.

Impacts of dietary calcium, phytate, and nonphytate phosphorus concentrations in the presence or absence of phytase on inositol hexakisphosphate (IP6) degradation in different segments of broilers digestive tract

A total of 1,440 straight-run Heritage 56M × fast-feathering Cobb 500F broiler birds were fed from 11 to 13 d of age to determine the impacts of calcium (Ca), phytate phosphorus (PP), nonphytate P (nPP) and phytase concentrations on the myo-inositol hexakisphosphate (IP6) flow through the different parts of gastrointestinal tract (GIT). The experiment was a 2×2×2×3 randomized block design with 2 Ca (0.7 and 1.0%), 2 PP (0.23 and 0.34%), 2 nPP (0.28 and 0.45%) and 3 phytase (0-, 500-, and 1,000-phytase unit (FTU)/kg) concentrations. The experiment was replicated twice (block) with 3 replicates per treatment (Trt) of 10 birds per block. Concentration of IP6 in crop, proventriculus (Prov) plus (+) gizzard (Giz) and distal ileum digesta as well as the ileal IP6 disappearance was determined at 13 d of age. In crop, higher IP6 concentration was seen with increased Ca (P < 0.05). Despite the interaction between PP and phytase, higher dietary PP led to greater IP6 concentration (P < 0.05). Similar main effects of PP and phytase were also seen in Prov+Giz and ileum (P < 0.05) without interactions. Interaction between Ca and nPP on IP6 concentration was seen in Prov+Giz (P < 0.05). Decreased ileal IP6 disappearance was found at higher Ca (62.3% at 0.7% Ca vs. 57.5% at 1.0% Ca; P < 0.05). In general, adding phytase improved IP6 degradation but the degree of impact was dependent on nPP and PP (P < 0.05). In conclusion, phytase inclusion significantly reduced IP6 concentration and IP6 disappearance in distal ileum regardless of GIT segments or diet composition, but impacts of dietary Ca, nPP, and PP differed depending on GIT segment examined.

Effect of high-dose phytase and citric acid, alone or in combination, on growth performance of broilers given diets severely limited in available phosphorus

1. Two trials were conducted to evaluate the effect of high-dose phytase alone or in combination with citric acid (CA) in the diet severely limited in available phosphorus (P) on performance, plasma P and plasma Ca of broilers from 22 to 42 d of age.2. In Trial 1, 297 21-d-old female chicks were placed into 27 pens and allocated to 9 maize-soybean meal-based dietary treatments, which were a positive control [PC, 4.23 g/kg non-phytate P (NPP)] and 8 negative control (NC, 1.35 g/kg NPP) groups consisting of two concentrations of CA (0 and 20 g/kg) and 4 concentrations of phytase (0, 1000, 2000 and 4000 U/kg) in a 2 × 4 factorial arrangement. In Trial 2, 192 21-d-old male chicks were placed into 24 pens and allocated to 6 wheat-canola meal-based dietary treatments, which were a PC (4.2 g/kg NPP), a NC (1.68 g/kg NPP) and 4 NC groups consisting of two concentrations of CA (0 and 20 g/kg) and two concentrations of phytase (2000 and 4000 U/kg) in a 2 × 2 factorial arrangement.3. In both trials, birds fed on the PC had significantly higher average daily gain (ADG), average daily feed intake (ADFI), plasma P and lower feed conversion ratio (FCR) and plasma Ca than those of birds fed on the NC. CA supplementation significantly increased ADG and ADFI. There was a significant interaction between CA and phytase on plasma P where CA improved the effect of phytase on plasma P. In Trial 1, phytase addition improved ADG, ADFI, FCR and plasma Ca linearly.4. Briefly, this research showed the interaction effect between CA and phytase on plasma P when broilers were fed on diets based on maize-soybean meal or wheat-canola meal. The results showed that CA supplementation lowered the concentration of phytase that is needed in low NPP diets to increase plasma P.

A meta-analysis of the effects of nonphytate phosphorus on broiler performance and tibia ash concentration

Decreasing feed costs while maintaining broiler performance at a high level with minimal environmental pollution has become a major challenge for poultry nutritionists in recent years. In this regard, phosphorus (P) is a nutrient that is problematic. To overcome this, a comprehensive knowledge of the responses of broilers to P is needed and the factors that affect its utilization need better understanding. For this purpose, a meta-analysis was conducted using results published in the literature on the responses of broilers to different levels of nonphytate P (NPP), calcium (Ca), microbial phytase (MP), and vitamin D3 or its metabolites (VD). The effects of Ca, MP, and VD on NPP requirements were investigated. Results showed significant (P ≤ 0.0001) linear and quadratic effects of NPP on all the responses, viz. average daily gain (ADG), feed intake (FI), feed efficiency (FE), and tibia ash concentration (TA). Results showed the negative effect of high Ca levels on all investigated responses, although these deleterious effects were alleviated when levels of NPP were increased or MP and/or VD added. Synergistic effects of MP and VD on FI and TA were observed. Best performance for all responses was found when MP and VD were added to low or moderate levels of Ca and NPP. Optimization showed higher levels of NPP are required to maximize TA compared to ADG, FI, and FE. Based on our analysis, requirements for NPP were affected mostly by Ca (increased) and MP (decreased), and, to a lesser extent, VD (inconsistent).

VITAMIN D3 ALLEVIATES CALCIUM AND PHOSPHORUS DEFICIENCY IN BROILERS

An experiment was carried out to examine effects of using extra dietary vitamin D3 along with low levels of calcium (Ca) and phosphorus (P) on performance, bone quality and mineral retention of broilers. Three starter diets were used; Control (C), Medium (M) and Low (L) which contain Ca: 1.00, 0.75 and 0.50%; non-phytate P (NPP): 0.50, 0.37 and 0.25%; D3: 3,000, 5,000 and 7,000 IU/kg, respectively. As well, three grower diets were used; (C), (M) and (L) contain Ca: 0.90, 0.65, and 0.40%; NPP: 0.45, 0.32 and 0.20%; D3: 3,000, 6,000 and 9,000 IU/kg, respectively. Six treatment groups were distributed according to diets fed in starter and grower periods consecutively; (C/C), (C/M), (C/L), (M/M), (M/L) and (L/L). Each group contained 40 birds in four replicates 10 chicks each. Body weight gain, feed efficiency, plasma concentration of Ca and P and plasma alkaline phosphatase activity, were not affected by dietary treatments compared to (C/C) except for (C/L) group. Similarly, tibia breaking strength, tibia ash and Ca and P percentage, were not affected by different dietary treatments except for (C/L) group which recorded lower bone density compared to (C/C) group. Birds of (C/L), (M/L) or (L/L) groups retained more Ca and P compared with those of other treatments. Based on results obtained, it could be concluded that extra vitamin D3 supplementations (9,000 IU/Kg) to low Ca and NPP (0.40 and 0.20%, respectively) diets could alleviate performance, bone quality and mineral retention, and decrease environmental pollution especially with P, as well as to minimize feed cost.