Feed conversion efficiency is measured in the beef industry by net feed intake (NFI), which is the amount of feed an animal requires compared to the average animal of the same weight and growth rate. NFI is an important component of the cost of beef production and hence its profitability. There is considerable genetic variation in NFI, but cattle breeders cannot select for this trait because it is too expensive to measure directly. Therefore, the aim of this project was to find genetic markers that could be used to select for NFI. Using lines of cattle selected for high and low NFI and a range of molecular and biochemical approaches, we have discovered over 100 genetic markers that are closely linked to genes affecting NFI. Although these markers could be used to select for NFI in the selection lines, they may not be close enough to the relevant genes to be used in other cattle populations. Therefore, before they are commercialised, their usefulness in other cattle populations needs to be validated and, where necessary, the existing markers should be used to find markers closer to the genes for NFI. This will lead to a panel of commercial DNA markers that cattle breeders can use to select for NFI.