Neutrophil and Monocyte Function in Neonatal Dairy Calves Fed Fresh or Frozen Colostrum

A study was conducted to compare neutrophil and monocyte activation in neonatal dairy calves fed fresh or frozen colostrum. Fifteen male Holstein calves were fed either refrigerator-stored, non-maternal colostrum or frozen, non-maternal colostrum. Blood samples were collected at days 2 and 21 of life to determine phagocytic cell function using flow cytometry. Serum immunoglobulin concentration was also measured at day 2 of life. It was found that calves fed frozen colostrum had a higher percentage of neutrophils activated at 2 days of age when compared to calves fed non-frozen colostrum. Neutrophil phagocytosis of bacteria, measured as an increase in fluorescence of neutrophils, percent monocytes activated and monocyte phagocytosis of bacteria were not different between the two colostrum groups. At 21 days of age, no statistical significance was found in any of the cell activation indices measured between calves fed fresh or frozen colostrum. There was no association found between immunoglobulin levels and type of colostrum fed. These results suggest that the role of fresh colostral leukocytes, as a key determinant for optimum immune function in the neonate, may not be as large of a factor as once thought, and that products of cellular destruction such as cytokines and transfer factor may be important in early cellular immune function.