Myo-inositol and low-P supply effects on intestinal processes of InsP6 degradation, absorption, and P utilisation in two contrasting high-yielding laying hen strains

先前对雏鸡和鹌鹑的研究表明，磷的利用与肠道植酸（InsP6）降解有关，并由饮食变量和鸟类的遗传背景引起。蛋鸡是特殊的，因为它们在产蛋期间需要非常高的膳食钙和低浓度的磷，但它们的需求在生命周期中急剧变化。因此，本项目的目的是研究蛋鸡InsP6降解产物以及植酸酶和碱性磷酸酶的黏膜活性与年龄、遗传背景和日粮变量的关系。利用显示出相当程度的遗传分化（FST=0.25）的棕色和白色莱格霍恩杂交品种进行了两项实验。试验1将在母鸡约30周龄的产蛋高峰期进行。饲粮变量为磷和钙的浓度，再加上杂交变量，它们被安排在一个2×2×2-factorial中，每个处理使用10只母鸡。试验2以杂交鸡和蛋鸡日龄为试验变量。在母鸡10、16、24、30和60周龄时取样，每次处理使用10只母鸡。饲粮应根据不同年龄阶段的特定需求进行调整，但对所有蛋鸡都是一样的。在这两个实验中，将研究低肌醇磷酸盐异构体、肌醇、钙和磷在作物、砂囊、十二指肠/空肠、回肠和盲肠中的含量。用二氧化钛作为难消化标记物来计算消失量。利用离体小肠顶端膜在体外测定粘膜酶活性。还研究了血浆和鸡蛋中肌醇的浓度。在研究单元的项目2中，使用Illumina 60K鸡Infinium iSelect芯片对所有母鸡进行基因分型。研究单位的项目3、4、5、7、8和9需要的样本使用联合制定的采样方案同时采集。除了回答本项目的具体研究问题外，所有数据将被整合到项目9的生物信息学数据处理和网络建设中，并与其他项目交换，以检验拟议研究单位的总体假设。

Previous studies using young chicken and quail have shown large variation in phosphorus utilization related to intestinal phytic acid (InsP6) degradation and caused by both dietary variables and the genetic background of the birds. Laying hens are specific because they need very high dietary calcium but low phosphorus concentrations in the laying period, but their requirements drastically change during lifespan. Therefore, the objective of the proposed project is to characterize degradation products of InsP6 and mucosal activity of phytase and alkaline phosphatase in laying hens in dependence on age, genetic background, and dietary variables. Two experiments are conducted using Brown and White Leghorn hybrids that show a substantial degree of genetic differentiation (FST=0.25). Experiment 1 will be conducted at around peak of egg production when the hens are approximately 30 weeks old. Dietary variables are the concentrations of phosphorus and calcium, and together with the hybrid variable they are arranged in a 2×2×2-factorial, using ten individual hens per treatment. In Experiment 2, the hybrid and the age of hens are the experimental variables. Samples are taken when hens are 10, 16, 24, 30, and 60 weeks old, using ten individual hens per treatment. Diets are adjusted to the specific requirement in each age period, but are the same for all hens. In both experiments, the appearance of lower inositol phosphate isomers, myo-inositol, calcium and phosphorus will be studied in content of crop, gizzard, duodenum/jejunum, ileum, and ceca. Disappearance is calculated by using titanium dioxide as the indigestible marker. Mucosal enzyme activities are measured in vitro using isolated apical membranes from the upper small intestine. Concentrations of myo-inositol are also studied in blood plasma and eggs. All hens are genotyped using the Illumina 60K chicken Infinium iSelect chip in project 2 of the Research Unit. Samples needed in projects 3, 4, 5, 7, 8, and 9 of the Research Unit are taken at the same time using a jointly developed sampling protocol. In addition to answering the specific research questions of this project, all data will be integrated into the bioinformatics data handling and network building made in project 9 and exchanged with the other projects in order to test the overarching hypotheses of the proposed Research Unit.