The aim of this research was to evaluate the influence of maternal cells from colostrum on the development and function of the innate immune response in Holstein calves. Calves were divided into 2 groups: COL+ (n=10) received fresh colostrum; and COL- (n=10) which received frozen colostrum containing no viable cells. The calves were assessed before colostrum intake (D0), 48h of age (D2), and weekly from D7 up to D28. Blood samples were collected for analysis of the distribution of leukocytes, cellular phenotype and in vitro granulocyte function. COL+ calves tended to have a high number of neutrophils on D7 (p=0.073). COL- calves took up significantly more Escherichia coli (measured as MFI) on D7 (p=0.034). Endogenous production of radicals (as percentage of cells) tended to be higher in COL- calves on D14 (p=0.061). The intensity of endogenous reactive oxygen species (ROS) produced by granulocytes tended to be higher in COL+ calves on D21 (p=0.094). Overall, ROS production (percent of cells, and MFI) induced by Staphylococcus aureus and Escherichia coli were higher in COL+ calves than COL- calves. It was our observation that COL+ calves developed an innate immune response more quickly and efficiently after natural exposure to pathogens after birth. In contrast, COL- calves mounted an innate response more slowly that yielded a persistent inflammatory response after natural exposure to these bacteria agents. This research provides evidence of an advantage to the calf of receiving fresh colostrum on the development and function of the innate immune system.

The objective of this research was to evaluate the influence of cells from colostrum on the health of neonate calves. Animals were distributed in 2 groups: COL+ (n=9) which received fresh colostrum from their own damns; and COL- (n=10) which received frozen colostrums from donors. Heifers were assessed before colostrum intake - D0; D2; D7; D14; D21 and D28. Heifers were monitored by clinical examination, hematological profile and serum iron. COL- had a higher diarrhea intensity score (typically 3) on D7. Moreover, a single case each of bronchopneumonia and navel inflammation were observed in COL- calves. COL- had fewer red blood cells (RBC) (6.5±0.8×10/μL) and less hemoglobin (Hgb) (8.3±1.4g/dL) than COL+ (RBC=7.2±0.8×10/μL; Hgb=9.6±1.3g/dL) at D14 (P≤0.05). COL- had more anemia on D21 (P=0.03) and on D28 (P=0.02). Iron was lower in COL- (5.6±2.7μM/L) than COL+ (10.7±6.2μM/L) (P=0.03) on D7. Lymphocytes was lower in COL- than COL+ on D7 (3.8±1.0×10/μL COL+ and 5.4±2.2×10/μL COL-, P=0.02). COL- calves had more anemia and lower serum iron concomitant with diarrhea on D7. The number of leukocytes was relatively consistent in the COL+ calves, while COL- calves showed an increasing number of of lymphocytes starting on D7.

No abstract

The detection of Bovine Viral Diarrhea virus (BVDV) infection, especially among persistently infected calves (PI), should be performed earlier in order to eliminate the source of the infection and to prevent the spread of the disease in the herd. However, colostrum intake can influence the results of some of the tests used to diagnose the BVDV infection. Therefore, this study evaluated the efficacy of serum neutralization (SN) test in conjunction with reverse transcription-polymerase chain reaction (RT-PCR) for the diagnosis of BVDV infection before colostrum intake. The deliveries of the animals were assisted to select 52 newborn Holstein calves for inclusion in the study. Initially, the whole blood and serum samples were collected from the calves before (T0) and after (T1) the colostrum intake. The calves that were RT-PCR positive at any of the time-points were retested on the 30 th day post birth (T2). The presence of specific antibodies for BVDV was evaluated by SN, and that of viral RNA by the RT-PCR. The BVDV-specific antibodies were observed in the serum of 13.46% (7/52) of the calves at T0 because of fetal infection. At T1, seroconversion was observed in 100% (52/52) of the calves. The geometric mean titers (GMT) of the antibodies for BVDV increased significantly from T0 (14.52) to T1 (2490) (P = 0.0001). Of the four calves that were RT-PCR positive before colostrum intake (T0), two were seronegative and two, seropositive. Of the forty-eight RT-PCR negative calves, five were seropositive. After 30 days post birth, all of the animals tested negative by RT-PCR, thus excluding the possibility of persistent infection. The association observed between the results of the SN and RT-PCR assays at T0 (P = 0.025) could not be observed at T1 (P > 0.05). The SN test before the colostrum intake allowed the detection of fetal infection in the herd; however, this test was ineffective as a diagnostic method after the transfer of passive immunity. The confirmation of the results of the SN assay by those of the RT-PCR was essential for the identification of the infected calves before colostrum intake. Key words: Bovine viral diarrhea. Passive immunity. Persistent infection. Polymerase chain reaction. Serum neutralization. ResumoInfecção causada pelo BVDV, especialmente bezerras persistentemente infectadas (PI), deve ser detectada precocemente para eliminação da fonte de infecção e disseminação da doença no rebanho. No entanto, a mamada de colostro interfere em alguns testes adotados para o diagnóstico da Diarréia Viral Bovina. Assim, esta pesquisa avaliou o uso da soroneutralização (SN) em associação com a reação em cadeia de polimerase precedida da transcrição reversa (RT-PCR) para diagnóstico da infecção pelo BVDV antes da mamada de colostro. Partos foram acompanhados para seleção de 52 bezerras da raça Holandesa. Inicialmente foram coletadas amostras de sangue total e soro de todos os animais antes (T0) e após a mamada do colostro (T1). Os animais positivos no RT-PCR em qualquer momento foram retestados aos 30 ...