Effects of low dietary phosphorus on tibia quality and metabolism in caged laying hens

Oligomeric proanthocyanidins ameliorates osteoclastogenesis through reducing OPG/RANKL ratio in chicken's embryos

Skeletal disorders can seriously threaten the health and the performance of poultry, such as tibial dyschondroplasia (TD) and osteoporosis (OP). Oligomeric proanthocyanidins (OPC) are naturally occurring polyphenolic flavonoid compounds that can be used as potential substances to improve the bone health and the growth performance of poultry. Eighty 7-day-old green-eggshell yellow feather layer chickens were randomly divided into 4 groups: basal diet and basal diet supplementation with 25, 50, and 100 mg/kg OPC. The results have indicated that the growth performance and bone parameters of chickens were significantly improved supplementation with OPC in vivo, including the bone volume (BV), the bone mineral density (BMD) and the activities of antioxidative enzymes, but ratio of osteoprotegerin (OPG)/receptor activator of NF-κB (RANK) ligand (RANKL) was decreased. Furthermore, primary bone marrow mesenchymal stem cells (BMSCs) and bone marrow monocytes/macrophages (BMMs) were successfully isolated from femur and tibia of chickens, and co-cultured to differentiate into osteoclasts in vitro. The osteogenic differentiation derived from BMSCs was promoted treatment with high concentrations of OPC (10, 20, and 40 µmol/L) groups in vitro, but emerging the inhibition of osteoclastogenesis by increasing the ratio of OPG/RANKL. In contrary, the osteogenic differentiation was also promoted treatment with low concentrations of OPC (2.5, 5, and 10 µmol/L) groups, but osteoclastogenesis was enhanced by decreasing the ratio of OPG/RANKL in vitro. In addition, OPG inhibits the differentiation and activity of osteoclasts by increasing the autophagy in vitro. Dietary supplementation of OPC can improve the growth performance of bone and alter the balance of osteoblasts and osteoclasts, thereby improving the bone health of chickens.

Effect of replacing dicalcium phosphate with mono-dicalcium phosphate to supplement phosphorus on laying performance, phosphorus-calcium metabolism and bone metabolism of aged laying hens

The objective of this study was to evaluate the effect of replacing dicalcium phosphate (DCP) with mono-dicalcium phosphate (MDCP) to formulate low-phosphorus (P) diets on laying performance, egg quality, phosphorus-calcium metabolism, and bone metabolism of 69-78-week-old aged laying hens. Hy-Line Brown laying hens (n = 1,350, 69 weeks old) were randomly assigned to six treatments, each with five replicates of 45 hens. A corn-soybean meal-based diet was formulated to contain 0.12% non-phytate phosphorus (NPP), 3.81% calcium (Ca), and 1,470 FTU/kg phytase. The control group (CON) was supplemented with DCP inorganic phosphorus (Pi) at the NPP level of 0.20% (dietary NPP levels of 0.32%). Test groups (T1-T5) were supplemented with MDCP Pi at NPP levels of 0.07%, 0.11%, 0.15%, 0.18, and 0.20% (dietary NPP levels of 0.19, 0.23, 0.27, 0.30, and 0.32%, respectively). Calcium carbonate levels were adjusted to ensure all experimental diets contained the same Ca levels (3.81%). The feeding trial lasted 10 weeks, with hens increasing in age from 69 to 78 weeks. When supplemented with 1,470 FTU/kg phytase, extra DCP Pi or MDCP Pi did not affect (p > 0.05) laying performance (day laying rate, average egg weight, feed intake, feed-to-egg mass ratio, broken egg rate), egg quality (eggshell strength, albumen height, haugh units), or serum P, Ca, copper (Cu), iron (Fe), zinc (Zn), and manganese (Mn) levels. However, when laying hens were fed MDCP Pi (NPP levels of 0.07 to 0.20%), yolk color improved (p = 0.0148). The tibia breaking strength was significantly higher (p < 0.05) in the 0.18 and 0.20% NPP MDCP Pi groups than in the 0.20% NPP DCP Pi group. The breaking strength, Ca content, and P content of tibia in 0.11% and 0.15% NPP MDCP Pi hens were not significantly (p > 0.05) different from those in 0.20% NPP DCP Pi hens. Hens fed 0.07% NPP MDCP Pi had higher (p < 0.01) serum levels of osteoprotegerin (OPG), type-I collagen c-telopeptide (CTX-I), and tartrate-resistant acid phosphatase 5b (TRACP-5b) than those in all other groups. Serum levels of TRACP-5b and CTX-I in the 0.11% and 0.15% NPP MDCP Pi group were significantly lower than those in 0.18 and 0.20% NPP MDCP Pi groups and the 0.20% NPP DCP Pi group (p < 0.0001). Hens fed 0.07% and 0.11% NPP MDCP Pi had higher (p < 0.05) serum levels of parathyroid hormone (PTH) than those in all other groups. No differences were detected in serum calcitonin (CT), 1,25-dihydroxy-vitamin D3 (1,25-(OH)2D3), bone alkaline phosphatase (BAP), osteocalcin(OCN), and osteopontin (OPN) among all groups (p > 0.05). The expression of P transporters type IIa Na/Pi cotransporter (NaPi-IIa) in 0.11% and 0.15% NPP MDCP Pi hens were higher than those in 0.20% NPP MDCP Pi group and 0.20% NPP DCP Pi group (p < 0.05). The results indicated that both renal P reabsorption and bone resorption were involved in adapting to a low-P diet. In summary, when MDCP was used instead of DCP to supplement P, NPP levels could be reduced to 0.11% (dietary NPP level of 0.23%) without negative effects on laying performance and skeletal health of aged hens. In addition, MDCP was more beneficial than DCP for tibia quality. The results of the current study would provide references for the application of MDCP in low-P diets of aged laying hens.

Osteocalcin and Its Potential Functions for Preventing Fatty Liver Hemorrhagic Syndrome in Poultry

Osteocalcin (OCN) is synthesized and secreted by differentiating osteoblasts. In addition to its role in bone, OCN acts as a hormone in the pancreas, liver, muscle, fat, and other organs to regulate multiple pathophysiological processes including glucose homeostasis and adipic acid metabolism. Fat metabolic disorder, such as excessive fat buildup, is related to non-alcoholic fatty liver disease (NAFLD) in humans. Similarly, fatty liver hemorrhage syndrome (FLHS) is a metabolic disease in laying hens, resulting from lipid accumulation in hepatocytes. FLHS affects hen health with significant impact on poultry egg production. Many studies have proposed that OCN has protective function in mammalian NAFLD, but its function in chicken FLHS and related mechanism have not been completely clarified. Recently, we have revealed that OCN prevents laying hens from FLHS through regulating the JNK pathway, and some pathways related to the disease progression have been identified through both in vivo and vitro investigations. In this view, we discussed the current findings for predicting the strategy for using OCN to prevent or reduce FLHS impact on poultry production.

Effects of Low-Phosphorus Diets Supplemented with Phytase on the Production Performance, Phosphorus-Calcium Metabolism, and Bone Metabolism of Aged Hy-Line Brown Laying Hens

This study was conducted to evaluate the effects of phytase supplementation in low-phosphorus diets on the production performance, phosphorus–calcium metabolism, and bone metabolism in laying hens from 69 to 78 weeks of age. Hy-Line Brown laying hens (n = 1350) were assigned randomly to six treatments with five replicates of 45 birds. A corn–soybean meal-based diet with no inorganic phosphates was formulated to contain 0.12% non-phytate phosphorus (NPP) and 1470 FTU/kg phytase (Released phytate phosphorus content ≥ 0.1%). Inorganic phosphorus (dicalcium phosphate) was supplemented into the basal diet to construct five test diets (level of NPP supplementation = 0.10%, 0.15%, 0.20%, 0.25%, and 0.30%). The level of calcium carbonate was adjusted to ensure that all six experimental diets contained the same calcium percentage (3.81%). The feeding trial lasted 10 weeks (hens from 69 to 78 weeks of age). Upon supplementation with phytase (1470 FTU/kg), supplemental inorganic phosphates (dicalcium phosphate) had no significant effects (p > 0.05) on the production performance or egg quality. Significant differences in serum levels of calcium, phosphorus, copper, iron, zinc, or manganese were not detected across treatments (p > 0.05). Hens fed NPP (0.15%, 0.20%, 0.25%, and 0.30%) had higher levels (p < 0.0001) of tibial ash, calcium, and phosphorus than those not fed inorganic phosphates. The tibial breaking strength of the group without inorganic phosphates was significantly lower than that of the other groups (p < 0.01). Dietary supplementation with inorganic phosphates had no effect (p > 0.05) on serum levels of calcitonin (CT) and 1,25-dihydroxy-vitamin D3 (1,25-(OH)2D3). Hens that did not receive supplementation with inorganic phosphates had higher serum levels of parathyroid hormone (PTH), osteoprotegerin (OPG), type-I collagen c-telopeptide (CTX-I), and tartrate-resistant acid phosphatase 5b (TRACP-5b) compared with those in the other groups (p < 0.01). Serum levels of CTX-I and TRACP-5b were significantly lower in the NPP-supplementation groups of 0.25% and 0.30% than in the 0.10% NPP-supplementation group (p < 0.01). Dietary supplementation with inorganic phosphates had no effect (p > 0.05) on serum levels of bone-alkaline phosphatase (BAP), osteocalcin (OCN), or osteopontin (OPN). Hens not fed inorganic phosphate had the highest renal expression of phosphorus transporter type IIa Na/Pi cotransporter (NaPi-Ⅱa). Renal expression of NaPi-Ⅱa was increased significantly in NPP-supplementation groups of 0.10–0.20% compared with that in NPP-supplementation groups of 0.25% and 0.30% (p < 0.0001). The results indicated that a reduction in NPP supplementation to 0.15% (dietary NPP level = 0.27%) with phytase inclusion did not have an adverse effect on the production performance or bone health of laying hens from 69 to 78 weeks of age, which might be attributed to renal phosphorus reabsorption and bone resorption. These findings could support the application of low-phosphorus diets in the poultry industry.

Effect of phytase and limestone particle size on mineral digestibility, performance, eggshell quality and bone mineralization in laying hens

The effect of microbial phytase and limestone particle size (LmPS) was assessed in Lohmann Tradition laying hens from 31 to 35 wk of age. Seventy-two hens were used in a completely randomized trial according to a 2 × 2 factorial arrangement with 2 levels of phytase/basal available P (aP); 0 FTU/kg with 0.30% aP or 300 FTU/kg with 0.15% aP, and 2 limestone particle sizes; fine particles (FL, <0.5 mm) or a mix (MIX) of 75% coarse limestone (CL, 2-4 mm) and 25% FL. Diets contained equivalent levels of Ca (3.5%), phytic P (PP; 0.18%), and aP (0.30%) considering the P equivalency of phytase. Thus, dietary treatments were FL0 and MIX0 without phytase, and FL300 and MIX300 with 300 FTU/kg phytase. Performance were recorded daily and eggshell quality (eggshell weight proportion, weight, thickness, and breaking strength) was measured weekly. At the end of the trial, bone parameters (tibia breaking strength, elasticity, and ash) and the apparent precaecal digestibility (APCD) of P and Ca were determined. No differences were observed between treatments in feed intake, FCR and bone parameters. Addition of MIX increased the eggshell proportion, weight and thickness in groups receiving no phytase (+6.5, +6.9, and +4.5%, respectively) while no effect was observed in groups receiving phytase (Phytase × LmPS, P < 0.05). In hens receiving FL, the APCD of P was lower in diets supplemented with phytase (-14 percentage points; Phytase × LmPS, P < 0.001). A higher phytate disappearance was observed in hens fed diets with phytase in combination with MIX (Phytase × LmPS, P = 0.005). Phytase and MIX together increased the APCD of Ca by 7.3 percentage points (Phytase × LmPS, P < 0.001). In conclusion, addition of CL could limit the formation of Ca-phytate complex thus improving the response of the birds to phytase compared to FL.

Serum bone remodeling parameters and transcriptome profiling reveal abnormal bone metabolism associated with keel bone fractures in laying hens

Keel bone fractures affect welfare, health, and production performance in laying hens. A total of one hundred and twenty 35-wk-old Hy-line Brown laying hens with normal keel (NK) bone were housed in furnished cages and studied for ten weeks to investigate the underlying mechanism of keel bone fractures. At 45 wk of age, the keel bone state of birds was assessed by palpation and X-ray, and laying hens were recognized as NK and fractured keel (FK) birds according to the presence or absence of fractures in keel bone. The serum samples of 10 NK and 10 FK birds were collected to determine bone metabolism-related indexes and slaughtered to collect keel bones for RNA-sequencing (RNA-seq), Micro-CT, and histopathological staining analyses. The results showed that the concentrations of Ca, phosphorus, calcitonin, 25-hydroxyvitamin D₃, and osteocalcin and activities of alkaline phosphatase and tartrate-resistant acid phosphatase (TRAP) in serum samples of FK birds were lower than those of NK birds (P < 0.05), but the concentrations of parathyroid hormone, osteoprotegerin, and corticosterone in serum samples of FK birds were higher than those of NK birds (P < 0.05). TRAP staining displayed that FK bone increased the number of osteoclasts (P < 0.05). Micro-CT analysis indicated that FK bone decreased bone mineral density (P < 0.05). Transcriptome sequencing analysis of NK and FK bones identified 214 differentially expressed genes (DEGs) (|log2FoldChange| > 1, P < 0.05), among which 88 were upregulated and 126 downregulated. Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) analysis indicated that 14 DEGs related to skeletal muscle movement and bone Ca transport (COL6A1, COL6A2, COL6A3, PDGFA, MYLK2, EGF, CAV3, ADRA1D, BDKRB1, CACNA1S, TNN, TNNC1, TNNC2, and RYR3) were enriched in focal adhesion and Ca signaling pathway, regulating bone quality. This study suggests that abnormal bone metabolism related to keel bone fractures is possibly responded to fracture healing in laying hens.

Effects of feeding strategies on eggshell quality of laying hens during late laying period

Insufficient calcium supply during the dark period is an important reason for deteriorated eggshell quality in laying hens. In the present study, the feeding time of hens was altered in order to investigate whether the changes in feeding time and feed consumption could influence the laying performance and eggshell quality of hens. A total of 192, 60-wk-old Hy-line Brown hens with similar body weight and laying rate were obtained. The hens were randomly divided into 4 groups and subjected to the following feeding strategies: feeding 3 times a day (control group, CON), or feeding once a day in the morning at 08:00 (MF), in the noon at 12:00 (NF), or in the afternoon at 16:00 (AF), respectively. The feeding strategies had no significant effect (P > 0.05) on laying rate, egg weight, and egg mass. Although the feed intake did not differ among treatments, the time phase of feed consumption was changed. From 15:00 to 21:00 h, hens consumed 49.7%, 42.4%, 49.1%, and 70.8% of daily feed intake in the CON, MF, NF, and AF groups, respectively. Feeding strategy had no detectable influence (P > 0.05) on egg shape index, eggshell strength, and eggshell percentage. Compared to CON, AF hens tended to have a higher eggshell thickness (P = 0.053). In MF and NF treatments, plasma calcium (Ca), phosphorus (P) levels, and alkaline phosphatase (ALP) activity did not differ (P > 0.05) compared with CON. In contrast, AF-hens had lower Ca and P levels, but a higher ALP activity than CON (P < 0.01). The AF hens had higher uterine fluid Ca than MF and NF hens (P < 0.05). Compared to CON, the expression level of CaBP-D28K was increased in the shell gland mucosa of MF-hens. Also, MF-, NF-, and AF-hens had higher Osteopontin (OPN) expression level (P < 0.05), whereas NF had a higher expression of OC-116 (P < 0.01). In conclusion, the results indicated that feeding in the afternoon changed the pattern of feed consumption and exerted a positive influence on eggshell thickness.

A simple daily dynamic feeding regimen for reducing phosphorus consumption and excretion in laying hens

Phosphorus metabolism in laying hens is a highly dynamic process over the course of the 24 h egg-laying cycle. Adjusting the phosphorus feeding regimen according to the daily egg-laying cycle may help to improve phosphorus utilization efficiency. Hy-Line Brown layers (n = 120; 70 wk old) were offered 4 different phosphorus daily regimens: (1) RR, fed regular phosphorus at both 09:00 and 17:00; (2) RL, fed regular phosphorus at 09:00 and low phosphorus at 17:00; (3) LR, fed low phosphorus at 09:00 and regular phosphorus at 17:00; (4) LL, fed low phosphorus at both 09:00 and 17:00. The regular and low phosphorus diets contained 0.32% and 0.14% non-phytate phosphorus, respectively. The feeding trial lasted for 12 wk. As a result, layers on the RL regimen had decreased laying rate (P < 0.05; 5 to 8, 9 to 12, and 1 to 12 wk) when compared to all other regimens. Layers on the LL regimen had decreased eggshell thickness and specific gravity (P < 0.05; wk 8) when compared to all other regimens, and had decreased egg shell strength (P < 0.05; wk 8) when compared to RL and LR regimens. When compared to the RR regimen (a common practice in the industry), layers on the LR regimen had: (1) identical laying performance and egg quality (P > 0.05); (2) decreased phosphorus excretion (P < 0.05) during the period of 09:00 to 17:00; (3) increased jejunal calbindin D28k protein expression (P < 0.05) 2 h after feeding in the morning; (4) decreased serum fibroblast growth factor 23 and calcitriol levels (P < 0.05), decreased jejunal type III sodium-phosphate cotransporter 2 gene and protein expression (P < 0.05), and decreased renal type III sodium-phosphate cotransporter 1 protein expression (P < 0.05), 2 h after feeding in the afternoon. In summary, when dietary phosphorus was supplemented in accordance with daily serum phosphorus rhythms (i.e., the LR regimen), laying performance and egg quality were well supported whilst significantly decreasing phosphorus consumption and excretion. Thus, serum phosphorus rhythms will need to be carefully maintained when developing dietary phosphorus-reduction strategies in laying hens.

Laying hens under smallholder conditions: laying performance, growth and bone quality of tibia and femur including essential elements

The study aimed to assess laying performance, growth rate, and bone quality properties of tibia and femur bones of various genotypes of laying hens, including determining essential element composition at the end of the laying cycle in smallholder conditions. The study included three genotypes of laying hens; Czech golden spotted (CGS), White Leghorn (LE) and Dominant Partridge D300 (D300) hens. In total, 180 hens (60/genotype) were used in 3 replications (20 hens/replication). The eggs were collected to determine egg lay and hen-day egg production. Additionally, feed consumption was recorded to determine feed consumption per day or egg, resp. The mortality rate was recorded. Hens were individually weighed every 10 wk to analyze the growth performance and body weight changes during the laying cycle. The differences in performance characteristics were observed as significant in all studied parameters. The bone quality analysis consisted of the determination of bone weight, length, width, and fracture toughness. Furthermore, dry matter, ash, and selected elements, which included boron (B), calcium (Ca), cadmium (Cd), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), lead (Pb), and zinc (Zn) were assessed. Regarding the results of tibia and femur bones, the effect of genotype was determined as significant in all evaluated properties. In terms of element composition, all evaluated elements significantly differed among the genotypes in the tibia (with one exception of Cu) and in the femur (with one exception of Cd). In conclusion, our results showed that hens’ performance, production quality, mortality and bone properties significantly differed among genotypes under smallholder conditions. Thus, every genotype needs to be carefully considered, when the rearing conditions are set.

Serum calcium–phosphorus product for predicting the risk of osteoporotic vertebral compression fractures in elderly patients: a retrospective observational study

Background

This study retrospectively analyzed and evaluated the potential correlations of serum calcium, serum phosphorus, and calcium-phosphorus product (Ca–P product) with the incidence of osteoporotic vertebral compression fractures (OVCFs), with the aim of exploring whether the Ca–P product can be used as a serological indicator to predict the risk of OVCFs.

Methods

This study randomly enrolled 400 elderly patients in our hospital with OVCFs and 400 patients with hip and knee arthroplasty due to femoral head necrosis or osteoarthritis from August 2013 to April 2021. Age, sex, past medical history, and admission biochemical indicators, including albumin, blood urea nitrogen, serum creatinine, serum calcium and serum phosphorus, were collected for statistical analysis.

Results

Albumin, serum calcium, serum phosphorus, Ca–P product, corrected serum calcium and corrected Ca–P product were lower in the OVCF group than in the non-OVCF group (P < 0.05). Multivariate logistic regression analysis showed that low values of serum calcium, serum phosphorus, Ca–P product, corrected blood calcium, and corrected Ca–P product can all be risk factors for OVCF. The ROC curve showed that the Ca–P product and corrected Ca–P product were effective in predicting the risk of OVCFs. The predictive value of the Ca–P product was the best; the cutoff point was 29.88, the sensitivity was 0.72 and the specificity was 0.62. The cutoff point of the corrected Ca–P product was 30.50, the sensitivity was 0.74, and the specificity was 0.62.

Conclusion

The Ca–P product and corrected Ca–P product can be used as serological indicators to predict the risk of OVCFs in elderly individuals. Early clinical interventions targeting this risk factor can further reduce the risk of OVCFs. Also, timely and regular testing of the serum calcium and phosphorus level is recommended and encouraged for this group of people.

Phosphorus Restriction in Brooding Stage Has Continuous Effects on Growth Performance and Early Laying Performance of Layers

Simple Summary

Phosphorus plays a critical role in bone and eggshell formation. Dietary phosphorus oversupply depletes non-renewable natural resources and causes environmental concerns in animal husbandry. This study evaluated the effects of phosphorus restriction in the brooding stage and subsequent recovery on growth performance, tibia development and early laying performance of layers. Phosphorus restriction decreases growth performance and bone characters in the brooding stage, and the adverse effects on body weight and early laying performance do not disappear after phosphorus supplementation. These findings give a foundation and new perspective on low phosphorus feeding strategies in the production of layers.

Abstract

This study evaluated the effects of phosphorus restriction in the brooding stage and subsequent recovery on growth performance, tibia development and early laying performance of layers. 360 one-day-old hens were randomly divided into 4 groups with 6 replicates and 15 chicks per replicate. Chicks were fed diets containing 0.13% (L), 0.29% (M), 0.45% (N), 0.59% (H) non-phytate phosphorus (nPP) from 1 to 8 weeks of age. From 9 to 20 weeks of age, the L and N group were divided into two groups fed normal level phosphorus (n, 0.39% nPP) and high-level phosphorus (h, 0.45% nPP) separately, then all the birds were fed a normal diet (0.39% nPP) from 21 to 26 weeks of age. Four treatments were tested: Ln, Lh, Nn, and Nh. The lower body weight, average daily feed intake, tibia length and daily tibial increment were observed in the L group (p < 0.05) and the ratio of feed to gain was significantly increased in the L group at 8 weeks of age (p < 0.05). In addition, the fresh and degreased tibia weight, bone ash, Ca content in the tibia and P content in the ash and tibia were significantly decreased in the L group at 8 weeks of age (p < 0.05). After compensatory processes, there was no significant difference in tibia characters; however, body weight in the Ln group was significantly lower than in the Nn group (p < 0.05) and was significantly lower in the Lh group than the Nn group (p < 0.01) and Nh group (p < 0.05). In addition, the laying rate and average daily egg mass in the Lh group were lower than Nn and Nh (p < 0.05). In conclusion, severe dietary phosphorus restriction impaired growth performance and bone mineralization in the brooding stage. Subsequent phosphorus supplementation could not alleviate this adverse effect on body weight, which continued to affect egg production. These findings give a foundation and new perspective on a low phosphorus feeding strategy in layer production.

Low dietary phosphorus impairs keel bone health and quality in laying hens

1. Phosphorus (P) is a necessary nutrient for egg production and bone quality in poultry diets. To investigate the effects of low dietary available P (avP) on keel bone, 180 laying hens were fed either a control (C, 0.3% avP) or low phosphorus (LP, 0.15% avP) diet from 20-36 weeks of age (WOA). Each diet was replicated in six cages with 15 birds per cage. Keel samples were collected at 24, 28, 32, and 36 WOA to measure indicators.2. The incidence of keel bone damage in the LP group was higher than C group and increased with age throughout the experiment period. Keel bone length from laying hens in the LP group was shorter than C group (P < 0.05) at 32 and 36 WOA.3. The mRNA expression of receptor activator of nuclear factor kappa-B ligand (RANKL) and ratio of RANKL to osteoprotegerin (OPG) were upregulated (P < 0.05), and that of sclerostin and OPG was downregulated (P < 0.05) in the LP group in comparison to hens in the C group. Meanwhile, mRNA expression of the integrin-binding sialoprotein was increased at 24 and 28 WOA (P < 0.05), and decreased at 32 and 38 WOA (P < 0.05) in the LP group.4. Laying hens in LP group had increased trabecular separation and bone surface fraction (P < 0.05), decreased bone volume, bone volume fraction, trabecular number and thickness, and bone mineral density (P < 0.05) at 32 WOA. The LP-fed hens had increased K, Ti, Mn, Fe, Zn, Se, Sr and Pb bone concentrations (P < 0.05), and decreased P and TI bone concentrations (P < 0.05) at 36 WOA.5. Feeding hens a P-deficient diet with 0.15% avP and 3.37% Ca during the laying period impaired keel bone quality, which could be related to the osteoporosis.