Betaine is a conditional supplement used in pig production which has been found to enhance growth of pigs, thereby reducing production costs. Further it can reduce fat deposition in carcasses resulting in fewer penalties for producers at processing. However, the key factors that determine the cost-effectiveness of betaine use, when and for how long it is supplemented, require further research. This project aims to maximise cost-effectiveness through exploring the optimal betaine supplementation levels for different phases of pig production.