Functional traits support production traits and are at the crossroads between responses to environment and the animal’s performance. They respond to environmental dynamics and affect the G-matrix between functional and production traits. When resources are allocated to one function, fewer resources will be available for other processes leading to trade-offs. Genetic control of resource allocation can cause changes in G. Functional traits can be improved through balanced selection strategies where they are incorporated in the selection index. Increasing global population calls for sustainable breeding where carbon footprint and environmental parameters are considered in the breeding objective. This would require new phenomics (electronic monitoring of input parameters, microbiome signatures, imaging technology, etc) modeled through analytical approaches based on “large data” and deep learning in order to not only refine current functional traits but also identify novel traits that are likely to describe functional traits and sustainability-related traits more accurately.