Ontogenesis of peptide transport and morphological changes in the ovine gastrointestinal tract

Abstract The purpose of this study was to examine developmental and dietary regulation of the potential for peptide transport via PepT1 and morphological changes in the gastrointestinal tract of lambs. A 2×4 factorial arrangement of treatments with four blocks was created based upon gender, birth type (single or twin), birth weight, birth date, and breeding with 32 cross-bred lambs. Lambs were randomly allotted at birth to receive or not to receive a creep diet and all lambs were allowed to nurse. Sampling times of 2, 4, 6, or 8 weeks were randomly allotted to lambs. Samples for RNA extraction and histological evaluation were taken from the dorsal rumen, ventral rumen, omasum, duodenum, jejunum, and ileum. The DMI was similar for ewes nursing lambs that had or did not have access to creep feed (2,630 and 2, 574 g h −1 per day, respectively). Lambs with access to creep feed consumed DM at the rate of 2, 22, 129, 219, and 227 g h −1 per day, respectively when they were approximately 12, 13, 20, 38, and 52 days of age. Cumulative weight gain was similar for both groups of lambs and increased linearly ( P P P P P P P P