RESUMO
Anti-soybean agglutinin (SBA) IgY was produced, and its potential to neutralize the haemagglutinating activity of SBA in vitro was tested. Thirty-five-week-old hens [treatment (n = 5) and control (n = 5)] were immunized with SBA or injected with saline 4 times every 15 days. Eggs were collected after the last immunization, and IgY was extracted using the polyethylene glycol (PEG) method. Serum anti-SBA IgY titres in immunized hens increased after the first immunization and reached a plateau between days 45 and 60. In contrast, specific IgY titres in the control group remained at basal levels throughout the evaluation. Average IgY titres were significantly higher in the treatment group on days 15, 30, 45, and 60. Total IgY content in the egg yolk extract was 38.7 ± 1.6 and 37.7 ± 1.5 mg/ml for the treatment and control groups, respectively. The specific anti-SBA IgY titer detected in the egg yolk extract was significantly higher (p < 0.001) for hens in the treatment group compared to the control group, with OD450nm values of 0.98 ± 0.05 and 0.058 ± 0.02, respectively. The specificity of anti-SBA IgY was confirmed by the Western blotting, and the inhibition of SBA-induced haemagglutination in vitro was compared with D-galactose, a known molecule that binds to SBA and blocks its binding to erythrocytes. The inhibition of SBA-induced haemagglutination by the anti-SBA IgY reached 512 units of haemagglutination inhibition (UHI), compared to 8 or 256 UHI, respectively, when IgY from control chickens or D-galactose was used. Thus, anti-SBA IgY antibodies were efficiently produced in large quantities and effectively inhibited SBA-induced haemagglutination in vitro.
RESUMO
Se evaluó el efecto del incremento de la temperatura de incubación en huevos de gallina Araucana sobre la tasa de eclosión, la mortalidad embrionaria, el peso del polluelo, del saco vitelino y de los órganos internos. Los huevos (n= 426) fueron distribuidos al azar en: a) grupo Control (n=215), incubados a 37,5 °C por 21 días y b) grupo Experimental (n= 211), incubados a 39,5 °C, por 18 días, disminuyéndose a 37,5 °C los 3 días restantes. En ambos grupos la incubación se realizó con una humedad relativa constante del 55 %. La tasa de mortalidad embrionaria total fue significativamente menor (P 0,05) para el grupo Control (14,9 vs 44,1 %) y consecuentemente la tasa de eclosión fue significativamente mayor (P 0,05) en este mismo grupo (97,8 vs. 80,5 %). El peso promedio de los polluelos y del saco vitelino a las 36 h post eclosión fue significativamente diferente (P 0,05) entre ambos grupos (37,1 vs. 36,3 y 2,5 vs 6,2 g para el grupo Control y Experimental respectivamente). Por otra parte, el peso de todos los órganos internos fue menor (P 0,05) en polluelos del grupo Experimental. Se concluye que el uso de una temperatura de incubación de 39,5 C por 18 días en huevos de gallina araucana influye negativamente, aumentando la mortalidad embrionaria, disminuyendo la tasa de eclosión, el peso del polluelo y de los órganos internos, y aumentando el peso del saco vitelino.
The aim of this study was to evaluate the effect of increasing incubation temperature of Araucana hen eggs on embryo mortality, hatchability,chick, yolk sac and internal organs weight. Eggs (n= 426) were randomly distributed into: a) Control group (n= 215), which were incubated at 37.5 °C for 21 days or b) Experimental group (n= 211), which were incubated at 39.5 °C, for 18 days and then at 37.5 °C for the remaining 3 days. In both groups eggs were incubated with a relative humidity of 55 %. The embryo mortality rate was greater (P 0.05) for the experimental than the control group (44.1 vs. 14.9 % respectively). On the contrary, hatching rate was greater (P 0.05) for the control than the experimental group (97.8 vs. 80.5 % respectively). The average weight of chicks, at 36 h of age, was lower (P 0.05) for the experimental than control group (36.3 vs. 37.01 g respectively). Also, increasing incubation temperature reduced (P 0.05) internal organs weight of chicks in the Experimental compared to Control group. On the other hand, yolk sac weight was reduced (P <0.05; 2.5 vs. 6.2 g for Control and Experimental group respectively). We conclude that increasing the incubation temperature of Araucana hen eggs up to 39.5 °C for 18 days has a negative effect on embryo survival, hatchability, chick and internal organs weight and absorption of yolk.
