In growing animals, feed efficiency is determined by the digestive and metabolic efficiency. The digestive efficiency is difficult to assess in a large number of animals. In pigs, its measurement requires to house animals in a digestibility cage during a prolonged period to measure feed intake and totally collect the faeces that should be analysed for the nutrient contents. The objective of this study is to identify an alternative methodology to characterize the digestive ability in pigs. For this purpose, 63 pigs from Large White, Pietrain, and Duroc breeds were fed alternatively two diets differing in crude fibre content (3.1 and 8.5% of dry matter) during four periods of three weeks each. The diets were supplemented with three molecules that may be used as indigestible marker: silicone oil, the plastic resin Kynar®, and polyethylene glycol. At each period, digestibility was measured using the gold standard as previously described. At the end of each period, a sample of faeces was also collected directly from the rectum of the pigs. All samples were also analysed by Near InfraRed Spectroscopy (NIRS). The digestive ability was variable among pigs during the growing period, especially when the diet contained a high level of fibre. The digestibility of this type of diet increased when body weight increased. The utilization of indigestible markers did not give satisfying results, because of low recovery in the faeces (plastic resin or polyethylene glycol) or because of large variability in the recovery (silicone oil). The NIRS prediction of digestibility coefficients from a sample collected directly in the faeces was adequate (bias of digestibility coefficients for dry matter, organic matter, energy, and N did not differ from 0%) when pigs were heavier than 60 kg and when they are fed a diet with a high fibre content. The method of collecting a single sample of faeces directly from the rectum of the pig and analysed by NIRS can be used in selection farms of breeders to give information on the digestive ability of individual pigs in a population. The Feed-a-Gene Project has received funding from the European Union’s H2020 Programme under grant agreement no 633531.