Maternally derived anti-fibroblast growth factor 23 antibody as new tool to reduce phosphorus requirement of chicks

FGF23 level in poultry chicken, a systematic review and meta-analysis

Introduction: In vertebrates fibroblast growth factor 23 (FGF23) is a phosphate regulating hormone closely linked to calcium regulation by vitamin D and parathyroid hormone (PTH). Although phosphorus, calcium and vitamin D are important for poultry well-being, relatively little is known about their levels of FGF23. Our objective was to quantitatively estimate the blood FGF23 level in birds, and to examine its relationship to diet and blood levels of other components of phosphate and calcium homeostasis. Methods: A systematic search of Agricola, Embase and Medline identified 86 studies focused on FGF23 in birds, from which 12 manuscripts reporting data for 60 independent groups of chickens were included in the analysis. Results: FGF23 levels were 256 pg/ml (Confidence interval (CI): 215, 297) in broilers (39 datasets containing 435 birds), and 256 pg/ml (CI: 178, 339) in egg-laying hens (21 datasets containing 208 birds). FGF23 levels did not correlate with dietary phosphorus, calcium or vitamin D, or with plasma calcium or PTH. FGF23 levels demonstrated a trend to positively correlate with plasma phosphate and a strongly and positive correlation with plasma vitamin D. Discussion: This study provides normative estimates of FGF23 levels in poultry birds and new insights into the regulation of calcium and phosphate homeostasis.

Supplemental Nicotinamide Dose-Dependently Regulates Body Phosphorus Excretion via Altering Type II Sodium-Phosphate Co-Transporter Expressions in Laying Hens

BACKGROUND

Dietary supplemental nicotinamide is used to treat hyperphosphatemia in humans. However, the mechanisms of its impact on body phosphorus homeostasis remain unclear.

OBJECTIVE

This study was to determine effects and molecular mechanisms of 3 dietary nicotinamide concentrations on body phosphorus homeostasis in laying hens.

METHODS

Hy-Line Brown layers (total = 21; 40 wk old; body weight: 1,876 ± 24 g) were individually housed (n = 7) and fed a corn-soybean meal-based diet supplemented with nicotinamide at 20 (N20), 140 (N140), and 1000 (N1000) mg/kg for 21 d. Serum phosphorus and fibroblast growth factor 23 (FGF23) concentrations, phosphorus and calcium excretion, and mRNA and/or protein of type II sodium-phosphate co-transporters (NPt2a, NPt2ab) and FGF23 and FGF23 receptors were measured in the intestines, calvaria, kidney, and liver.

RESULTS

Hens in the N1000 group had a 16% lower serum phosphorus concentration and 22% greater phosphorus excretion than those in the N20 or N140 group (P ≤ 0.05). Compared with hens in the N20 group, hens in the N140 and N1000 groups, which did not differ, had 15-21% lower serum FGF23 concentrations, 19-22% greater calcium excretion, 43-56% lower ileum NPT2b protein production, and 1.5- to 1.6-fold greater kidney NPT2a protein production, respectively (all differences at P ≤ 0.05).

CONCLUSIONS

Supplementing high concentrations of nicotinamide in diets for laying hens led to accelerated phosphorus and calcium excretions and decreased serum phosphorus and FGF23 concentrations, which were associated with downregulated intestinal NPt2b protein production. Our findings exclude kidney NPt2a protein production as a primary mechanism for the nicotinamide-induced body phosphorus loss.

Effect of inorganic phosphate supplementation on egg production in Hy-Line Brown layers fed 2000 FTU/kg phytase

Phytase has long been used to decrease the inorganic phosphorus (Pi) input in poultry diet. The current study was conducted to investigate the effects of Pi supplementation on laying performance, egg quality and phosphate-calcium metabolism in Hy-Line Brown laying hens fed phytase. Layers (n = 504, 29 weeks old) were randomly assigned to seven treatments with six replicates of 12 birds. The corn-soybean meal-based diet contained 0.12% non-phytate phosphorus (nPP), 3.8% calcium, 2415 IU/kg vitamin D3 and 2000 FTU/kg phytase. Inorganic phosphorus (in the form of mono-dicalcium phosphate) was added into the basal diet to construct seven experimental diets; the final dietary nPP levels were 0.12%, 0.17%, 0.22%, 0.27%, 0.32%, 0.37% and 0.42%. The feeding trial lasted 12 weeks (hens from 29 to 40 weeks of age). Laying performance (housed laying rate, egg weight, egg mass, daily feed intake and feed conversion ratio) was weekly calculated. Egg quality (egg shape index, shell strength, shell thickness, albumen height, yolk colour and Haugh units), serum parameters (calcium, phosphorus, parathyroid hormone, calcitonin and 1,25-dihydroxyvitamin D), tibia quality (breaking strength, and calcium, phosphorus and ash contents), intestinal gene expression (type IIb sodium-dependent phosphate cotransporter, NaPi-IIb) and phosphorus excretion were determined at the end of the trial. No differences were observed on laying performance, egg quality, serum parameters and tibia quality. Hens fed 0.17% nPP had increased (P < 0.01) duodenum NaPi-IIb expression compared to all other treatments. Phosphorus excretion linearly increased with an increase in dietary nPP (phosphorus excretion = 1.7916 × nPP + 0.2157; R2 = 0.9609, P = 0.001). In conclusion, corn-soybean meal-based diets containing 0.12% nPP, 3.8% calcium, 2415 IU/kg vitamin D3 and 2000 FTU/kg phytase would meet the requirements for egg production in Hy-Line Brown laying hens (29 to 40 weeks of age).

The adaptability of Hy-Line Brown laying hens to low-phosphorus diets supplemented with phytase

Body phosphorus homeostasis network allows laying hens to adapt to wide range of changes in dietary phosphorus levels. Phytase hydrolyzes phytate rendering phosphorus and reduces the laying hens' requirements for inorganic phosphate rock. Here, we demonstrate that there is no need to keep large safety margins in dietary phosphorus when hens are fed with phytase. Hy-Line Brown laying hens (n = 504) were randomly assigned to 7 treatments (6 replicates of 12 birds). A corn-soybean meal–based diet, with no inorganic phosphate rock, was formulated to contain 0.12% nonphytate phosphorus (nPP), 3.8% calcium, and 2,000 FTU/kg phytase. Inorganic phosphate rock (di-calcium phosphate) was supplemented into the basal diet to create 6 other diets containing 0.17, 0.22, 0.27, 0.32, 0.37, and 0.42% nPP. Levels of calcium carbonate and zeolite powder were adjusted to make sure all the 7 experimental diets contained the same nutrition levels (including calcium and phytase) except nPP. The diets were subjected to laying hens from 29 to 40 wk of age. As a result, when supplemented with 2,000 FTU/kg phytase, extra supplementation of inorganic phosphate rock had no effects (P > 0.05) on serum phosphorus levels, serum calcium levels, laying performance (laying rate, egg weight, feed intake, feed-to-egg ratio, and unqualified egg rate), egg quality (shell thickness, shell strength, albumen height, yolk color, and Haugh unit), and tibia quality parameters (breaking strength and ash, calcium, and phosphorus contents). Extra supplementation of inorganic phosphate rock linearly increased (P < 0.01) fecal phosphorus excretion and linearly decreased (P = 0.032) the apparent metabolizability of dietary phosphorus. While serum hormones and intestine gene expressions were varied within treatments, no consistent changes were found. In conclusion, the supplementation of inorganic phosphate rock (provided 0.05–0.30% extra nPP) to phytase-containing basal diets (2,000 FTU/kg; nPP = 0.12%) provided limited benefits to egg production performance in laying hens from 29 to 40 wk of age. Further investigating the body phosphorus homeostasis would help to understand the nutritional and physiological reasonability of formulating low-phosphorus diets in the laying hen industry.

Phosphorus Restriction Changes the Expression of Fibroblast Growth Factor 23 and Its Receptors in Laying Hens

Dietary phosphorus oversupply wastes non-renewable natural resources and raises environmental concerns in animal agriculture. We hypothesized that laying hens do not need large safety margins for dietary phosphorus because of the existence of fibroblast growth factor 23 (FGF23). In experiment 1, a total of 504 Hy-Line Brown laying hens (40-week-old) were randomly assigned to seven diets (for each diet, six replicates of 12 hens), containing 0.12, 0.17, 0.22, 0.27, 0.32, 0.37, and 0.42% non-phytate phosphorus, respectively, for 15 weeks. In experiment 2, a total of 14 Hy-Line Brown laying hens (40-week-old) were randomly assigned to two diets: (1) phosphorus restricted (n = 7) diet containing 0.14% non-phytate phosphorus, and (2) regular phosphorus (n = 7) diet containing 0.32% non-phytate phosphorus, for 21 days. Laying performance and egg quality were investigated in experiments 1 and 2. Phosphorus excretion and physiological changes were determined in experiment 2. It was found that dietary non-phytate phosphorus levels had no effects (P > 0.05) on laying performance and egg quality in either experiment. In experiment 2, laying hens fed 0.14% non-phytate phosphorus had decreased phosphorus excretion (by 52.6%, P < 0.001) when compared to those fed 0.32% non-phytate phosphorus. In response to the 0.14% non-phytate phosphorus diet, laying hens in experiment 2 exhibited: (1) suppressed calvaria mRNA expressions of FGF23 (by 57.8%, P < 0.001) and fibroblast growth factor receptor 1 (FGFR1, by 52.8%, P = 0.012), (2) decreased serum levels of FGF23 (by 41.7%, P = 0.011) and phosphorus (by 40.3%, P < 0.001), (3) decreased kidney mRNA expressions of FGFR1 (by 66.0%, P = 0.040) and FGFR4 (by 63.3%, P = 0.012) and decreased kidney protein expression of type 2a sodium-phosphorus co-transporter (NPt2a, by 51%, P = 0.025), (4) increased duodenum protein expression of NPt2b (by 45%, P = 0.032), and (5) increased excretion of calcium (by 22.9%, P ≤ 0.024). Collectively, decreasing dietary non-phytate phosphorus by up to 0.12% had no negative effects on egg-production performance but significantly decreased phosphorus excretion in laying hens. The laying hens adjusted to low-phosphorus diets by increasing intestinal NPt2b protein production, which was associated with decreased serum FGF23 concentration. Decreasing dietary non-phytate phosphorus is suggested to laying-hen nutritionists.

Effect of anti-fibroblast growth factor 23 antibody on phosphate and calcium metabolism in adenine gavaged laying hens

Dietary factors such as adenine have been linked to phosphate-calcium metabolism disturbance and adverse productive outcomes. Anti-fibroblast growth factor 23 (FGF-23) antibody has been proposed to ameliorate adenine-induced abnormal FGF23/phosphate metabolism. This experiment was conducted to investigate the application of anti-FGF-23 antibody in adenine-gavaged laying hens. Single Comb White Leghorn laying hens with (n = 10) or without (control group, n = 10) systemic anti-FGF-23 antibody were orally gavaged with adenine (600 mg/hen/D) for 21 consecutive days. Adenine gavage increased (P ≤ 0.01) plasma phosphate and calcium levels and tended to increase (0.05 < P ≤ 0.1) plasma 1,25-dihydroxy-cholecalciferol [1,25(OH)2D3] level of hens without FGF-23 antibody. In hen with anti-FGF-23 antibody, adenine gavage increased (P ≤ 0.01) body weight and plasma calcium level and decreased (P ≤ 0.05) plasma FGF-23 level. Feed intake of hens in both treatments was suddenly decreased (control hens decreased from 111 to 55 g, P ≤ 0.01; anti-FGF-23 hens decreased from 96 to 46 g, P ≤ 0.01) 10 D after adenine gavage. Anti-FGF-23 antibody tended to increase (0.05 < P ≤ 0.1) plasma phosphorus level of hens before adenine gavage, interestingly, and decreased (P ≤ 0.01) plasma FGF-23 level and kidney index (% of body weight) of hens after adenine gavage. In conclusion, anti-FGF-23 antibody might be used (before or in the early stage) to delay the development of adenine-induced abnormal FGF23/phosphate metabolism. This is the first study to investigate the FGF-23 status in chickens suffering from dietary factors which may cause abnormal renal phosphate resorption.

Lack of a relationship between plasma fibroblast growth factor-23 and phosphate utilization in young chicks

Fibroblast growth factor 23 (FGF-23) is proposed to be the hormone that controls phosphate (P) homeostasis in chickens. This study was initiated to investigate the effect of feeding young chicks diets that were either adequate (0.45%) or marginal (0.25%) in available P content on plasma FGF-23 levels. The dietary level of available P significantly (P ≤ 0.05) affected bone mineralization and bone length, but was without effect (P > 0.05) on growth rate and circulating FGF-23 concentrations. Substantial individual variation in bone mineralization and plasma FGF-23 levels was observed, and the correlation between these two variables was non-significant (P > 0.05). This suggested that there was no alteration in FGF-23 activity in response to suboptimal dietary P intake. The relationship of these observations to studies on the immunosuppression of FGF-23 activity is subsequentlydiscussed.

Vaccine to fibroblast growth factor 23 peptides increases eggshell strength

Strategies that would increase eggshell quality could be of considerable value to egg producers. This research demonstrated the effective use of fibroblast growth factor 23 (FGF-23) peptide vaccines to increase eggshell quality of Single Comb White Leghorn laying hens (from 69 to 72 wk of age). Hens, fed a standard diet (containing 900 IU/kg vitamin D3), were intramuscularly injected (and boosted) with either a control vaccine (n = 14 hens) or one of 2 FGF-23 peptide vaccines (peptides NP1, GMNPPPYS; and NP7, YTSTERNSFH; n = 15 hens for each peptide). During peak antibody titer, eggs were collected for shell and internal quality analysis, hens were artificially inseminated, and the hatchability of fertilized eggs was determined. Laying hens vaccinated with either FGF-23 peptide NP1 or NP7 had increased (P < 0.05) plasma phosphate level (mmol/L; NP1 = 1.74, NP7 = 1.76, control = 1.47), egg specific gravity (NP1 = 1.083, NP7 = 1.083, control = 1.079), and eggshell strength (g of force; NP1 = 4002, NP7 = 4157, control = 3102) when compared to control vaccinated hens. FGF-23 peptide NP1 vaccinated hens also had increased eggshell thickness (mm, P < 0.001), shell weight (g, P = 0.032), and shell index (% of whole egg, P = 0.023) when compared to control vaccinated hens. FGF-23 peptide NP7 vaccinated hens tended to have decreased eggshell weight (P = 0.064) when compared to control vaccinated hens. Hatchability of fertilized eggs was not affected in incubations 1 and 3, but tended to be decreased (P = 0.097) by FGF-23 peptide NP1 vaccination in incubation 2. In conclusion, vaccines to FGF-23 peptides increased eggshell quality of laying hens with minimal adverse effects on egg internal quality. The effect of FGF-23 peptide vaccination on hatchability remains to be clarified.

Additive effects of fibroblast growth factor 23 neutralization and dietary phytase on chick calcium and phosphorus metabolism

Phytase hydrolyzes phytate rendering phosphorus available for intestinal absorption, while systemic neutralization of fibroblast growth factor 23 (FGF-23), using anti-FGF-23 antibody, has been shown to increase phosphate retention. Hence, neutralization of FGF-23 should be additive with phytase in reducing dietary non-phytate phosphorus (nPP) needs in chickens fed plant-based diets rich in phytic acid. This study was designed to test the additive effects of maternally derived anti-FGF-23 antibody and dietary phytase on the performance of chicks fed a low nPP diet from one to 14 d. Single Comb White Leghorn laying hens were vaccinated with either an adjuvant control or a synthetic FGF-23 peptide (GMNPPPYS). Chicks from vaccinated hens with control or anti-FGF-23 maternal antibodies were fed either a diet containing 0.2% nPP and 0.9% calcium with or without 500 unit phytase per kg of diet (2 × 2 factorial with main effects of antibody type and phytase addition, n = 15 pens of chicks/treatment). A significant interaction between dietary phytase and maternally derived anti-FGF-23 antibody on growth and feed efficiency was observed (P ≤ 0.05), in which chicks receiving either phytase or maternally derived anti-FGF-23 antibody had improved body weight gain (21 or 15%, respectively) and feed efficiency (16 or 18%, respectively) as compared to chicks with control antibody and not fed phytase. Both phytase and maternally derived anti-FGF-23 antibody independently increased (P ≤ 0.05) plasma phosphate (11 and 11%, respectively) and percent tibiotarsus ash (13 and 11%, respectively). Significant main effects and the lack of an interaction supported an additive effect of phytase and anti-FGF-23 antibody on plasma phosphate and percent tibiotarsus ash. Feeding phytase to chicks fed 0.2% nPP increased plasma FGF-23 levels by 22% (P ≤ 0.05); however, no effects of anti-FGF-23 antibody on plasma FGF-23 levels were observed. In conclusion, dietary phytase and presence of anti-FGF-23 antibody have an additive effect on plasma phosphate and tibiotarsus ash in chicks fed low nPP diets. Data support that phytase and anti-FGF-23 antibody increase phosphate utilization by different mechanisms.