Plasma Concentrations of Gut Peptides in Dairy Cattle Increase after Calving

摘要

Effects of transition from late gestation to early lactation on plasma concentrations of glucose-dependent in-sulinotropic polypeptide (GIP), glucagon-like peptide 1-(7-36) amide (GLP-1), and cholecystokinin (CCK) have not been reported in cattle. The objective of the present study was to measure plasma concentrations of GLP-1, GIP, CCK, insulin, glucose, and nonesterified fatty acids in blood plasma obtained from the coccygeal vein of 32 Holstein cows at an average of 11 d before, and 5,12, and 19 d after calving. Feed dry matter intake (DMI) averaged 14.4, 17.7, and 19.9 kg/d on d 5, 12, and 19 of lactation, respectively, as milk yield increased (30.6, 36.6, and 39.7 kg/d, respectively). Plasma concen-trations of insulin and glucose were lower postpartum than prepartum, but did not differ among samples col-lected after calving. In contrast, plasma concentration of gut peptides increased linearly after calving, perhaps as a consequence of increased feed intake and nutrient absorption; however, the increases in plasma concen-trations of GIP and GLP-1 as lactation progressed were not associated with increased DMI per se, and likely reflect the endocrine and metabolic adaptations of lacto-genesis. In contrast, increased concentration of CCK was related both to increasing days in milk and DMI. By 19 d postpartum, concentrations of GLP-1, GIP, and CCK increased by 2.3-, 1.8-, and 2.8-fold, respectively, compared with values at 11 d before calving. Although these peptides have direct and indirect effects that re-duce appetite and DMI in other species (including in-creased insulin secretion), these may be glucose- or in-sulin-dependent functions, and insulin and glucose con-centrations were reduced in early lactation.