The objective of this work was to study the immunological behavior of newborn Mangalarga and Angle-Arabian foals, the acquiring process of maternal immunoglobulins and its correlation to the levels of colostral immunoglobulin. The Mangalarga and Angle-Arabian foals serum immunoglobulins were analysed by the ZST (Zinc Sulfate Turbidity) method. The results were tested by mathematical models which study the biological process of passibe immunity transfer in that period of observation: to the Mangalarga foals the tested model was: y = 23.9274 - 0.39766X + 6.4675 10-3 x², with r = 0.91 and P < 0.01 to Angle-Arabian foals was: y = 34.161 - 0.756062X + 0.015604X² - 1.013 10-3 x³, with r = 0.96 and P < 0.05. Estimation of the colostral IgG concentration was based on total protein concentration measured by Micro-Kjeldhal method. The results of this study allowed the following conclusions: (1) higher passive IgG in foals serum delayed the stablishment of normal Ig level; (2) animals which acquired lower quantities of passive IgG showed more intense response of endogenous Ig production; (3) colostrum estimated IgG concentration showed positive correlation Serum IgG concentration of the foals at the point of maximal absorption showed positive correlation with colostrum estimated IgG.
passive immunity; foal; colostrum