Vaccination of goats against Haemonchus contortus with the gut membrane proteins H11/H-gal-GP

Forty goats, aged from 2 to 5 months were subjected to two different immunization protocols with a vaccine containing Haemonchus contortus gut membrane proteins H11/H-gal-GP to evaluate protection against H. contortus on pre-contaminated pastures. Goats were allocated to four groups of ten, three of them received their first vaccination before turnout. One group (V4) was then vaccinated at 4-week-intervals whereas another two groups (V6 and V6SEP) were vaccinated at 6-week-intervals. A control group (CTRL) remained unvaccinated. In May, after the second vaccination, all goats were turned out on pastures which had been previously contaminated with H. contortus eggs by seeder sheep for a period of six weeks. Goats of groups V4, V6 and CTRL were grazed together, whereas V6SEP was kept separately at an identical stocking rate. Clinical (PCV, FAMACHA, body weight), parasitological (faecal egg count, FEC) and serological (antibody titres) parameters were measured fortnightly. All goats were stabled in October, drenched with levamisole and two weeks later infected with 5000 L3 of H. contortus and slaughtered four weeks later for determination of abomasal worm burdens. Group mean FEC peaked 42–56days after turnout. Significantly lower FEC were observed in V6SEP vs CTRL between D 28 and 70 (p