Project 1.1

Age, diet, and strain effects on inositol phosphates and myo-inositol in the digestive tract of hens

Markus Rodehutscord / Korinna Huber

Previous studies using young chicken and quail have shown large variation in phosphorus utilization related to intestinal phytic acid (InsP6) degradation. This was caused by both dietary variables and the bird’s genetic background. Laying hens are specific because they need very high dietary calcium but low phosphorus concentrations in the laying period. Their requirements drastically change during lifespan.

Therefore, the objective of this 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.

Results

The objective of the study Sommerfeld et al. 2020 was to compare 2 laying hen strains in 5 production periods regarding phytase activity, phytate (InsP6) degradation, and myo-inositol (MI) release in the digestive tract and phosphorus (P) and calcium (Ca) utilization. In jejunum digesta, the MI concentration did not differ between strains, but InsP6 concentration was higher in LB than in LSL hens and the highest in week 30 and 60. Total phosphatase and phytase activities were higher in LB than in LSL hens. Period effects were also significant for these enzymes. Concentrations of some constituents of the cecal content were different between the strains. The MI concentration in the egg albumen and yolk was higher in LB than in LSL hens. Differences in InsP6- and MI-related metabolism of the 2 hen strains existed. These differences were partly dependent of the period. Especially, week 24 was a period of remarkable change of metabolism. Great differences also existed among individuals, making it worth to have a closer look at the metabolism of individuals in addition to evaluating treatment means. Further studies on metabolic, genetic, and microbiome level may help explain these differences.

Concentrations of inorganic P, Ca, and myo-inositol in the blood plasma of 2 laying hen strains (LB and LSL) in different weeks of life. The concentration of inorganic P was higher in LB than in LSL hens and higher in weeks 10, 16, and 60 than in week 30, which was higher than week 24. The concentration of Ca was increased with each week. The concentration of myo-inositol did only differ between strains in week 60, causing a strain*period interaction.
Abbreviations: Ca, calcium; LB, Lohmann Brown-classic; LSL, Lohmann LSL-classic; MI, myo-inositol; P, phosphorus.
Summary of traits that were shown to be significantly higher in one laying hen strain than in the other.

The objective of the study Sommerfeld et al. 2020 was to characterize intestinal phytate degradation, ileal transcript copy numbers of transcellular Ca and P transporters, and mineral utilization by two laying hen strains fed with standard or reduced levels of dietary Ca and P at the laying peak. The strains showed differences regarding several traits driving Ca and P metabolism along the digestive tract. Thus, the two strains may use different mechanisms to meet their respective P demand, i.e., via effective phytate degradation and transcellular transport. Clear effects of the Ca level on myo-inositol concentrations and mineral utilization revealed the significance of this element for the measured traits. The absence of P-mediated effects confirmed the findings of several studies recommending that P concentrations used in laying hen feeds are too high. Differences were noted between individuals within one treatment. The next step would be to evaluate the data in individual birds to identify birds that better cope with a challenging diet.

Project leaders

Prof. Dr. Markus Rodehutscord
Institut für Nutztierwissenschaften, Fachgebiet für Tierernährung
+49 711 459 22420
E-mail

Prof. Dr. Korinna Huber
Institut für Nutztierwissenschaften, Fachgebiet für Funktionelle Anatomie der Nutztiere
+49 711 459 23998
E-mail

Staff

Dr. Vera Sommerfeld
Institut für Nutztierwissenschaften, Fachgebiet für Tierernährung
+49 711 459 22366
E-mail

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