No abstract

To establish reference values and to assess the influence of age on the leukograms of healthy Holstein calves, blood samples were obtained from 300 animals. These samples were distributed equally (n=20) among 15 experimental groups according to age: birth to 8 hours, 9 to 16 hours, 17 to 24 hours, 2 days, 3 days, 4 days, 5 days, 6 to 7 days, 8 to 9 days, 10 to 11 days, 12 to 13 days, 14 to 15 days, 16 to 20 days, 21 to 25 days and 26 to 30 days of age. The maximum numbers of leukocytes (9,305.0/mL), segmented neutrophils (6,551.2/mL) and total neutrophils (6,678.3/mL) were noted within the first 8 hours of life, while band neutrophils peaked in number (133.3/mL) between 9 and 16 hours after birth. Meanwhile, the maximum total lymphocyte (4,992.1/µL) and typical lymphocyte (4,686.1/µL) counts occurred between 21 and 25 days, whereas atypical lymphocytes (388.5/µL) reached their maximum number between 26 and 30 days, demonstrating an inversion of the neutrophil:lymphocyte ratio over time. Thus, the influence of age on the leukocyte count of the evaluated calves was verified. The release of endogenous corticosteroids during labor or at birth may contribute to this variation in leukograms with age.

RESUMO Foram estabelecidos critérios de interpretação do teste de tuberculinização aplicado ao diagnóstico da

This work aimed to study the possible relationships among the magnitude of abomasal worm burden and the proliferation of globular leucocytes and mucosal mast cells in the abomasal mucosa, and the white blood cell count. Eighteen Suffolk × Greyface lambs were infected with Haemonchus contortus, and 12 were kept free of nematodes. Blood samples were collected on days 0, 30, and 57 post-infection (p.i.) for leucogram determination. At day 62, all animals were euthanized to count the total number of nematodes recovered in the abomasum and to count the number of mucosal mast cells and globular leucocytes. On day 57, higher levels of parasitism corresponded to lower leucocyte counts. The infected groups had lower lymphocyte counts throughout the experimental period. Animals with higher numbers of parasites had lower neutrophil and eosinophil counts on day 57. The lower the worm burden, the greater the number of mucosal mast cells (r=-0.85; p<0.01) and globular leucocytes (r=-0.87, p<0.01) observed. The sheep most resistant to haemochosis had greater peripheral and tissue cellular immune responses.