Functional signals for vitamin D-mediated mineral utilization and related physiological determinants in pigs

• Applicant: Dr. Henry Reyer
• Subject Area: Animal Breeding, Animal Nutrition, Animal Husbandry
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 503753038

The minerals phosphorus and calcium are essential for skeletal mineralization and many other metabolic and immunological traits. As part of homeostasis, endogenous regulatory processes ensure a balance in the absorption, utilization, retention and excretion of phosphorus and calcium. Different interactions in the complex regulation of mineral homeostasis in pigs have been elucidated by studies on (i) physiological adaptation after variable phosphorus and calcium supply and (ii) genetic analyses of phosphate levels in blood as part of our own work. These findings provide the basis for new hypotheses, particularly about the cross-tissue functions of the vitamin D system and individual variability at the level of bone metabolism. To further elucidate the genetic contribution to the variation in mineral balance at the level of vitamin D metabolites (calcidiol, calcitriol), collagen fragments (β-CTX, CICP), and extracellular non-collagenous bone matrix (osteocalcin) in blood, genome-wide association analyses (GWAS) will be performed. For this purpose, a sampled and genotyped resource population of the FBN will be used. The project will identify genomic regions and candidate genes linked to mineral homeostasis. By generating another pig population, comprising German Landrace and Angler Saddleback pigs, an in-depth phenotyping approach will be performed to reveal intrinsic processes of mineral homeostasis. Analyses include serum, bone, urine, and feces to quantify mineral turnover, vitamin D metabolites, markers of bone turnover, and bone composition and function. The collected data allow the discrimination of discordant animals in terms of vitamin D-mediated mineral homeostasis. This subset of animals forms the experimental basis for further analyses to fine map genetic determinants of mineral utilization (whole-genome sequencing; mRNA profiling). The integration of native pig breeds such as the Angler Saddleback pigs, which are considered more robust to environmental factors, offers the opportunity to identify divergent strategies for maintaining mineral homeostasis and their effects on bone and immune system. Overall, the project considers genetic, transcriptional, and endocrine factors influencing the dynamics of mineral homeostasis in pigs as a basis for their application in breeding, monitoring, and sustainable use of phosphorus and calcium in pig production.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Michael Oster