Ghrelin Levels in Dairy Calves: Influence of Postnatal Separation from the Dam in Commercial Farms

Conventional management systems in dairy farms are based on the separation of the dam from the calf immediately after calving. However, early contact with the dam may ease the nutritional transition by allowing more frequent colostrum and milk intake, potentially influencing ghrelin regulation, a hormone whose secretion increases during fasting, serving as a potential biomarker of hunger. This longitudinal study aimed to evaluate serum ghrelin concentrations in dairy calves managed under 2 different systems: (1) conventional separation from the dam immediately after birth and (2) dam-calf contact for at least 24 h postpartum. Data were collected from 8 Holstein dairy farms in Galicia, Spain. Serum samples were taken from 24 calves in the dam-calf contact system at 3 time points: just before separation (T1), 2 d after separation (T2), and 7 d after separation (T3). Additionally, 24 age-matched calves in the conventional system were sampled at the same postpartum time points. Ghrelin concentrations were measured using a commercial ELISA kit and the statistical analysis was conducted using a linear mixed model. Results revealed that calves allowed dam contact exhibited significantly lower ghrelin concentrations at all sampling times compared with those separated immediately after birth. These findings suggest that early maternal contact may reduce hunger-driven ghrelin secretion, likely due to improved satiety. This study highlights the influence of early-life management on endocrine responses in dairy calves and supports the potential benefits of dam-calf contact systems. Further research is needed to explore the long-term impacts on calf development and production efficiency.