Protocols: The animal trial was performed at the Agricultural Experimental Station of the University of Hohenheim, Germany. The experimental protocol is in strict compliance with the German Animal Welfare Legislation and approved by the Regierungspräsidium Tubingen, Germany, and the Animal Welfare Committee of the University of Hohenheim (Project no. HOH67-21TEr). The hens were fed the experimental diets for a period of four weeks before slaughtering in week 19 (n = 40) and week 24 (n = 40), respectively. Medullary bone was dissected, snap-frozen in liquid nitrogen and stored in -80 °C.  Frozen medullary bone was ground with pestle and mortar in liquid nitrogen. Total RNA was isolated using TRI reagent (Sigma-Aldrich) and phenol-chloroform-based extraction according to the TRI reagent protocol. To remove trace carry-over DNA contamination, the RNA was treated with DNase I (Roche Diagnostics) and purified using the NucleoSpin RNA extraction kit (Macherey-Nagel). The RNA concentration was determined using the NanoDrop ND-2000 (Peqlab) and the RNA quality was analyzed using Bioanalyzer 2100 device (Agilent Technologies). High quality RNA (RIN > 7) was used for sequencing library construction using the Illumina Stranded mRNA preparation kit (Illumina, San Diego) according to the manufacturer's recommendations.