PREPARTURIENT VACCINATION TO ENHANCE PASSIVE-IMMUNITY TO THE CAPSULARPOLYSACCHARIDE OF PASTEURELLA-HAEMOLYTICA A1

The potential to increase passive serum antibody titres to a polysacch aride antigen in neonates, by preparturient vaccination of the dams wa s investigated. Dairy cows in five private herds were vaccinated with a commercial Pasteurella haemolytica culture supernatant vaccine (Pres ponse(R) Langford Inc.), at 6 and 3 weeks before their calculated due dates. Darns' sera, colostral whey, and post-colostral calf sera were assayed for antibodies of the IgGl isotype binding purified capsular p olysaccharide of P. haemolytica Al, using an enzyme immunoassay, Antib ody titres were analyzed using the General Linear Model procedure (Sta tistical Analysis Systems Institute Inc.), Vaccinated darns had a sign ificant increase in serum antibody titre after vaccination compared wi th non-vaccinates (P<0.01), and their antibody titres in colostral whe y were significantly higher (P<0.05), Calves of vaccinated dams had si gnificantly higher passive antibody titres than those of non-vaccinate s (P<0.01) in all herds.