Assessment of Eimeria gallopavonis dose for vaccination strategies in turkeys

Three experiments were conducted to determine the appropriate dose level of E. gallopavonis for autogenous vaccine production to manage its highly virulent nature. In experiment 1, birds were divided into four groups: 0 (Non-inoculated Control, NIC), 30, 90, or 270 E. gallopavonis oocysts per poult (OPB); experiment 2 included NIC, 30, and 90 OPB, while experiment 3 tested NIC, 15, and 30 OPB. Body weight and oocysts per gram of excreta (OPG) were enumerated in experiment 1 on d7 and d14, in experiments 2 and 3 on days 7, 14, 21, and 28. For experiment 1, no differences (p > 0.05) were observed in OPG; BW decreased significantly (p < 0.05) in the 30 and 270 OPB groups, and a 45% mortality in the 270 OPB group was recorded. In experiment 2, d28, BW in 90 OPB at 776g was lower (p < 0.05) than NIC birds at 846g. OPG peaked at d14 in pens receiving 30 OPB and those on 90 OPB, but both declined by d28. Lastly, vaccination with 15 OPB in experiment 3 did not affect BW, but 30 OPB levels were lower at d21 and d28 (p < 0.05). OPG levels with those on 30 OPB were significantly higher (p < 0.05) on d21 compared to 15 OPB and NIC. Similarly, mortality was high in the 30 OPB group at 47%, while the 15 OPB and NIC were 9% and 7%, respectively. Among all the dose levels, 15 OPB recorded the lowest adverse effects; however, concern about the consistency of infection at this low dose remains, and thus, additional vaccine management strategies are needed.