Abstract
ABSTRACT The hematological and immunological development of calves from birth to 6 months of age was performed by hemogram and cellular phenotype. Ten male Holstein calves were assessed in 13 moments: before colostrum intake (D0), every 2 days until the 10th day of life (D2 to D10), at the 15th day after birth (D15), and then monthly up to 6 months (D180). Calves presented hemoconcentration on day (D) 0 and showed a gradual decrease in hematimetric rates until D180. The inversion of the neutrophilic for lymphocytic profile was observed on D4. The percentage of CD3+ cells on D10 was higher than D30 up to D180. The number of CD4+ and CD8+ cells did not change between time points. The number of CD21+ lymphocytes was significantly higher at early time points of D0 up to D15, compared on D30 until D150. In conclusion, the neonatal period was marked by stress leukogram in the first 4 days, and low number of B lymphocytes. These might be risk factors for bacterial infections responsible for navel inflammation and diarrhea. The increase in the number of B cells from 30 days of age demonstrated that the calves were functional and able to generate an immune response.
Highlights
Newborn calves are considered immune-naïve and agammaglobulinemic at birth, because of the synepitheliochorial placenta from dams, which prevents the passage of pathogens to the fetusProgesterone, prostaglandins, and the cytokines interleukin (IL)-4 and IL-10, produced by the placenta during pregnancy, are responsible for the suppression of the Th1 maternal response, which releases toxic cytokines for the fetalplacental environment
The bovine colostrum is rich in immunoglobulin G1 (IgG1), cells, and cytokines
The dams were vaccinated against foot and mouth disease and Brucella abortus according to the Brazilian official program. These animals were vaccinated in the pre-partum period by subcutaneous injection of 5mL of commercial multivalent vaccine containing inactivated strains of Bovine viral Diarrhea Virus (BVDV) type 1 (5960) isolated in Iowa (USA) and BVDV type 2 (53637) isolated in Ontario (USA); live/thermosensitiveBovine Herpesvirus 1 (Cooper) and Parainfluenza-3 Virus (RLB 103); live-attenuatedBovine Respiratory Syncytial Virus diluted in the adjuvant with "Quil A, cholesterol and amphigen." The vaccinations for bovine respiratory disease were administered twice, 8 and 4 weeks before the expected delivery dates
Summary
Newborn calves are considered immune-naïve and agammaglobulinemic at birth, because of the synepitheliochorial placenta from dams, which prevents the passage of pathogens to the fetusProgesterone, prostaglandins, and the cytokines interleukin (IL)-4 and IL-10, produced by the placenta during pregnancy, are responsible for the suppression of the Th1 maternal response, which releases toxic cytokines for the fetalplacental environment. Newborn calves are considered immune-naïve and agammaglobulinemic at birth, because of the synepitheliochorial placenta from dams, which prevents the passage of pathogens to the fetus. Mononuclear leukocytes are the predominant cells in the mammary secretion, especially CD14+ macrophages (39.6%), B lymphocytes (24.5%), CD4+ T lymphocytes (13.8%), and CD8+ T lymphocytes (19%) (Park et al, 1992). These cells are absorbed by the newborn intestinal mucosa and have been identified in the blood stream and lymph nodes after fresh colostrum intake (Liebler-Tenorioet al., 2002;Reberet al., 2006)
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