Updated publication reference for PubMed record(s): 29258228. Here, we used reverse-phase liquid chromatography-coupled tandem mass spectrometry to study the pre-weaned lamb proteome and metaproteome in ten different gastrointestinal tracts: rumen, reticulum, omasum, abomasum, duodenum, jejunum, ileum, cecum, colon, and rectum.