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

以前对幼鸡和鹌鹑的研究表明，磷的利用与肠道植酸(InsP6)的降解有关，并由饮食变量和鸟类的遗传背景引起。蛋鸡是特殊的，因为它们在产蛋期需要非常高的日粮钙和低的磷浓度，但它们的需求在一生中发生了巨大的变化。因此，该项目的目标是研究蛋鸡InsP6降解产物、植酸酶和碱性磷酸酶粘膜活性与年龄、遗传背景和日粮变量之间的关系。用棕色和白色来航力杂交进行了两个实验，显示出相当程度的遗传分化(FST=0.25)。试验一将在产蛋高峰期进行，此时母鸡大约30周龄。日粮变量是磷和钙的浓度，与杂交变量一起，它们被安排在2×2×2因子中，每个处理使用10只母鸡。在实验2中，鸡的杂交种和年龄是实验变量。在母鸡10周龄、16周龄、24周龄、30周龄和60周龄时采集样本，每个处理使用10只母鸡。日粮根据每个年龄阶段的具体需要进行调整，但对所有母鸡都是相同的。在这两个实验中，将研究较低的肌醇磷酸异构体、肌醇、钙和磷在作物、胃、十二指肠/空肠、回肠和盲肠内容物中的出现。消失率是通过使用二氧化钛作为消化标志来计算的。使用分离的小肠顶膜在体外测定粘膜酶的活性。还研究了血浆和鸡蛋中肌醇的浓度。在研究单位的项目2中，所有的母鸡都使用Illumina 60K鸡肉iSelect芯片进行了基因分型。研究股项目3、4、5、7、8和9所需的样本是使用共同制定的抽样方案同时采集的。除了回答本项目的具体研究问题外，所有数据都将被整合到项目9中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.