Immune response assessment in turkey breeder (Meleagridis gallopavo) under Newcastle vaccine virus by mathematical models.

80 serum samples from 1 to 385 days-old flocks were collected in 10 breeder farms. Samples were submitted to the haemagglutination inhibition test (HI). Geometric mean titre (GMT) were transformed into base 10 logarithms, and the average were plotted in a dispersion diagram, with a X independent variable (birds age) and a Y dependent variable (antibodies titre). When Regression and Variance analyses were applied to the data, the regression coefficient of determination was too low (r2=0,46). The data have been segregated in 3 segments, increasing the new regression coefficient of determination. The following results were observed: 1 to 42 days-old birds have presented a linear equation, with a coefficient of determination of 0,99, where Y=2,86+0.064X. A quadratic equation were obtained from 63 to 245 days-old birds presenting a coefficient of determination of 0,96, where Y=6,01-0,0007X+0,00023X2. The best-fitted equation for 245 to 385 days-old birds was linear, with a coefficient of determination of 0,91, where Y=3,01-0,0009X. From these results we can conclude that is possible building a regression model and its graphic and mathematical representation using the relation between birds age and antibodies titre. Collecting samples at shorter intervals (once a week) and standardising all the limiting factors that have been a damage to result generation and to analyses get a standard serological curve building for a specific situation and company, resulting in a safe interpretation of serologic results.