Lower serum IgG concentrations in Montbéliarde neonatal: A comparative study on breed-specific passive transfer success.

In cattle, passive immunity relies entirely on the intake and intestinal absorption of colostral immunoglobulins after birth; however, breed-specific differences in passive transfer efficiency remain incompletely characterized. This study aimed to compare passive immunity status among Holstein, Jersey, and Montbéliarde calves under standardized colostrum management conditions, thereby minimizing colostrum-related variability and evaluating potential breed-associated differences in immunoglobulin G (IgG) absorption. The study was conducted on a single commercial dairy farm under uniform management conditions. A total of 42 newborn calves were enrolled, including Holstein (n = 15), Jersey (n = 15), and Montbéliarde (n = 12) calves. All calves received colostrum within the first six hours postpartum at a standardized volume corresponding to 10-12% of body weight. Colostrum quality was evaluated using Brix refractometry, and ELISA determined colostral IgG concentrations. Blood samples were collected from calves at approximately 36 h after birth to assess serum IgG concentrations. No significant differences were observed among breeds in colostrum Brix values, colostral IgG concentrations, serum Brix values, or serum total protein concentrations (p > 0.05). In contrast, serum IgG concentrations differed significantly among breeds (p < 0.05), with Holstein calves exhibiting the highest values (20.90 ± 3.61 g/L), followed by Jersey (17.52 ± 6.95 g/L) and Montbéliarde calves (12.70 ± 8.55 g/L). Breed-specific correlation patterns between colostrum and serum parameters were identified, particularly in Montbéliarde calves. In conclusion, despite comparable colostrum quality and standardized colostrum intake, Montbéliarde calves demonstrated significantly lower serum IgG concentrations than Holstein and Jersey calves. These findings suggest that passive transfer efficiency may be influenced by breed-specific physiological or genetic factors independent of colostrum IgG content.