Effect of Calving Time on Serum Total Protein Concentration and Passive Transfer Status in Holstein Calves

Successful transfer of passive immunity (TPI) is essential for the health and long-term productivity of newborn calves. While colostrum quality and intake have been extensively investigated, the influence of calving time on TPI remains poorly understood. This study evaluated the effect of calving time on serum total protein (STP) concentration and passive immunity transfer in newborn Holstein calves. A total of ۱۰۷ calves from a commercial dairy farm were assigned to four groups based on birth time: Group ۱ (۰۶:۰۰–۱۱:۵۹ h), Group ۲ (۱۲:۰۰–۱۷:۵۹ h), Group ۳ (۱۸:۰۰–۲۳:۵۹ h), and Group ۴ (۰۰:۰۰–۰۵:۵۹ h). Blood samples were collected ۴۸ h after colostrum feeding, and STP concentrations were measured using a handheld optical refractometer. Data were analyzed using one-way ANOVA followed by Bonferroni post-hoc comparisons. Calving time significantly affected STP concentration (P < ۰.۰۵). Calves born during daytime hours had significantly higher STP concentrations (Group ۱: ۷.۲۴ ± ۰.۵۱ g/dL; Group ۲: ۷.۱۲ ± ۰.۷۲ g/dL) than calves born during nighttime hours (Group ۳: ۶.۶۲ ± ۰.۶۶ g/dL; Group ۴: ۶.۵۹ ± ۰.۴۷ g/dL; P < ۰.۰۵). No significant difference was observed between Groups ۱ and ۲ (P > ۰.۰۵). These findings suggest that calving time may influence passive immunity transfer in neonatal calves. Improved monitoring and standardized colostrum management during nighttime calving may help optimize calf health and passive immunity status.

کلیدواژه ها:

Holstein calves ، Colostrum ، Passive immunity transfer ، Serum total protein ، Calving time.