Brown and white adipose tissues have different metabolic functions. Brown adipose tissue (BAT) is responsible for non-shivering thermogenesis, which principally protects the young from hypothermia. BAT is also involved in diet induced thermogenesis in adults and it has been shown to be inversely correlated with BMI. White adipose tissue (WAT) is primarily an energy store in the physical form of triglycerides that functions to regulate energy homeostasis. WAT also has extensive endocrine functions. Using an ovine model we investigated the developmental transition of perirenal adipose tissue in the fetus (BAT) through to the lamb at 4 months of age (WAT). The transition was associated with large transcriptional changes as measured by RNA-Seq. We have also mapped epigenetic profiles for H3K27me3, H3K4me3 and H3K27ac using genome wide ChIP-Seq for the same tissues. This study confirmed the involvement of a number of specific genes in the BAT to WAT transition and also identified many unexpected and largely ‘anonymous’ genes. Chromatin marks were information rich in terms of their position, types, gene activity and gene function. In particular, integration of this information revealed strong relationships between promoter localised chromatin marks and transcriptional silencing or activation. Understanding the factors that regulate the transition from BAT to WAT may help define novel strategies that enhance postnatal BAT mass and activity in humans and livestock thereby potentially protecting individuals from metabolic diseases and enhancing new born lamb survival, respectively. The potential impact of maternal nutrition prior to embryo implantation on this perirenal adipose tissue developmental transition is currently under investigation.