Nutritional Endocrinology in Dairy Cattle: Roles of the Ghrelin and Glucagon-Like Peptide Axis in Metabolic...

High-producing dairy cattle experience profound metabolic transitions during the periparturient and periweaning periods that influence health and long-term productivity. In ruminants, feed intake and metabolic adaptation reflect coordinated interactions among rumen fermentation, hepatic oxidative feedback, and gastrointestinal hormones. This review summarizes evidence on ghrelin and the glucagon-like peptide (GLP) axis and organizes recent findings within a hierarchical framework linking rumen-derived substrates, intestinal nutrient sensing, and systemic endocrine responses. Ghrelin increases during negative energy balance in early lactation and appears to support metabolic mobilization, whereas its orexigenic effect is constrained by ruminant-specific intake control. Evidence also indicates that postruminal amino acid supply and fatty acid profile can modulate ghrelin secretion, highlighting the importance of the digestive site and nutrient type. The GLP axis complements this regulation. GLP-1 links postruminal nutrient-related signals with insulin dynamics and satiety, whereas GLP-2 is more closely related to intestinal growth and adaptation during developmental transitions, including weaning. Notably, improvements in intestinal development in early life do not always coincide with large or sustained changes in circulating GLP-2. Overall, viewing dairy nutrition through endocrine responses, alongside nutrient supply, provides a basis to interpret variable outcomes in transition cows and calves and refine feeding strategies across physiological stages.