Assessment of the minimal available phosphorus needs of laying hens: Implications for phosphorus management strategies

Abstract

The oversupply of dietary phosphorus (P) leads to increased feed costs and discharge of excessive P to the environment, thus directly impacting the sustainability of egg production practices. The present study was conducted to better define the minimal available P needs of laying hens. Fifty-six Lohmann white laying hens were individually caged and fed one of 7 diets with graded levels of available P (0.15, 0.20, 0.25, 0.30, 0.35, 0.40, or 0.45%) for 12 weeks. Records were maintained for body weight, feed intake, and egg production during the experimental period. Blood and egg samples were collected and digestibility studies conducted at wk 6 and 12 of the experiment. At the end of the experiment, tibia characteristics and expression of the P transporters in the small intestine and kidney were determined. Lowering dietary available P from 0.45 to 0.15% generally reduced plasma P concentrations (P < 0.01), but hen productive performance, plasma calcium, parathyroid hormone and other constituents, tibia bone mineral density and content, tibia ash percentage, and mRNA abundance of the small intestine, and kidney type II sodium/phosphate cotransporter were not different among treatments. Specific gravity and eggshell thickness tended to increase with reducing dietary P (P < 0.05). Total P intake, excretion, and retention net amount decreased (P < 0.01) with reducing dietary P, but its retention rate (of intake) remained unchanged. Furthermore, changing dietary P did not affect calcium retention rate and net deposition of total P and calcium in eggs. These data indicate that reducing dietary available P up to 0.15% is adequate to maintain health and performance of layers. As such, this minimal available P estimate should serve as a benchmark for the assessment of P contents of commercial laying hen rations, with the goal of enhancing the sustainability of egg production.

A Comparison of Morphometric Indices, Mineralization Level of Long Bones and Selected Blood Parameters in Hens of Three Breeds

“…In general, plasma P concentration in Sussex hens was lower than that observed in end-of-lay hens by other authors (Dobrzański et al, 2011;Świątkiewicz et al, 2015). However, Jing et al (2018) reported that plasma or serum contain only a small part of total P deposited in the body, which is why changes in plasma P concentration may not necessarily reflect changes in the whole body. This is consistent with our study, because at 64 weeks we found no differences in crude ash or P content of the analysed bones between the breeds.…”

Dietary calcium or phosphorus deficiency impairs the bone development by regulating related calcium or phosphorus metabolic utilization parameters of broilers

“…The frozen tibiae were thawed at room temperature for 2 h and then stripped of all soft tissues. The tibia BMD ( Liu et al., 2017 , Jing et al., 2018 ) was determined by dual-energy X-ray absorptiometry. The tibia BBS was determined by a 3-point bending test (HDP/3PB Texture Analyzers, West Sussex, UK).…”

The Effect of Dietary Rye Inclusion and Xylanase Supplementation on Structural Organization of Bone Constitutive Phases in Laying Hens Fed a Wheat-Corn Diet

“…A scan of the whole bone was performed using the "small animal" mode of the enCORE ® software (version 17.0 (2016); GE, Madison, WI, USA) and a special pad for "small animal" scans provided by the producer densitometer, which was used to eliminate measurement artifacts and to immobilize the bones so that all the bones were scanned in the coronal plane. No additional objects were used to mimic the soft tissue around bone [17,18,44]. The measurements were carried out on the scanned data using operator-defined regions of interest (ROIs) covering the central, 40 mm long fragment of the tibial bone, at the mid-diaphysis.…”