Humoral and cellular immune responses of piglets after castration at different ages

Abstract

In this study, growth of piglets and their humoral and cellular immune responses were used to evaluate the effect of castration at different ages. Piglets (n = 84) from 14 litters were assigned to one of the six treatments: castration or sham-castration at 3, 10 or 17 d of age. An injection of bovine serum albumin (BSA) was given on the day of castration and a second one 14 d later. Blood samples were taken at different times to evaluate the antibody levels against BSA and lymphocyte blastogenesis responses to concanavalin A (Con A), phytohaemagglutinin (PHA) and pokeweed mitogen (PWM). The age of piglets at the first immunization significantly influenced (P < 0.0001) the ability to raise antibodies to the injected antigen. Three-day-old piglets developed weaker antibody response than those immunized at 10 or 17 d of age. Ten- and 17-d-old castrated piglets tended to develop weaker secondary antibody responses than sham-castrated piglets, while those castrated and sham-castrated at 3 d of age did not differ in their antibody response (interaction castration × age; P < 0.08). The fluctuation in lymphocyte blastogenesis response between days 21 and 35 was numerically greater in castrated than in shamcastrated piglets. Ratios between days 35 and 21 of PWM proliferative indexes were significantly higher (P < 0.05) in piglets castrated at 10 or 17 d of age than in sham-castrated piglets. The results indicate that castration of piglets at 10 d of age or older impairs antibody response to BSA and modulates piglet lymphocyte responses to mitogens. Castration at 3 d of age had no marked effect on antibody response and lymphocyte proliferation. Thus castration appears to be less disruptive to immune response if performed at three days of age compared to 10 d of age or older. Key words: Castration, stress, antibody formation, lymphocytes, pigs