EVALUATION OF SALMONELLA-ENTERITIDIS-IMMUNE LYMPHOKINES ON HOST-RESISTANCE TO SALMONELLA-ENTERICA SER GALLINARUM INFECTION IN BROILER CHICKS

The prophylactic treatment of neonatal broiler chicks with lymphokines derived from S. enteritidis-immunized chickens (SE-ILK) was evaluated for its effect on the birds' resistance to an experimental infection S. enterica ser, gallinarum (SG). On the day of hatch, chicks were inj ected intraperitoneally with either SE-ILK, control nonimmune lymphoki nes (NILK), or were left untreated. Thirty minutes later, all chicks w ere orally gavaged with either 10(4) colony forming units (CFU) or 10( 6) CFU SG. The chicks were observed twice daily for 10 days for morbid ity and mortality. Chicks that died during the experiment had their li vers cultured for SG. The survivors were killed and their livers, sple ens and caecal tonsils cultured for SG. The prophylactic treatment of chickens with SE-ILK induced significant protection against extraintes tinal SG infection when compared to the NILK-treated or non-treated co ntrols as evidenced by: (1) a significant reduction (P<0.005) in the m ortality of chicks challenged with either 10(4) and 10(6) CFU SG; (2) an increased average weight gains of chicks challenged with either 10( 4) and 10(6) CFU SG; and (3) a significant (P<0.001) reduction in the number of chicks with organs culture-positive for SG. The results sugg est that the prophylactic administration of SE-ILK can confer non-spec ific protection to chicks against a pathogenic species of Salmonella r esulting in reduced morbidity, mortality, and organ infectivity caused by SG infections of broiler chicks, while enhancing performance durin g the first 10 days of life.