APSS 2013 Proceedings - The University of Sydney

Aust. Poult. Sci. Symp. 2013.....24
mortality was higher in chickens challenged with FT158 (33%) than MPF57 (10%) (P =
0.002). In challenged chickens it was also higher in unvaccinated (30%) than vaccinated
(13%) (P = 0.002). Similarly the incidence of MD lesions was higher in chickens challenged
with FT158 (65%) than MPF57 (39%) (P = 0.005) and higher in unvaccinated (76%) than
vaccinated (28%) (P < 0.0001)
Table 1 - Mortality and incidence of MD in the experiment
Treatment
Numbers and percentages of affected chickens
Mortality Mortality with MD MD lesions
FT158/Unvacc 13/30 (43%) 13/30 (43%) 28/30 (93%)
FT158/Vacc 7/30 (23%) 7/30 (23%) 11/30 (37%)
MPF57/Unvacc 5/30 (17%) 4/30 (13%) 17/29 (59%)*
MPF57/Vacc 1/30 (3%) 1/30 (3%) 6/30 (20%)
Vacc/Unchall 0/26 (0%) 0/26 (0%) 0/26 (0%)
Unvac/Unchall 0/30 (0%) 0/30 (0%) 0/30 (0%)
Overall 26/176 (15%) 25/176 (14%) 62/145 (43%)
*One chicken excluded as it died early due to a clearly non-MD related cause.
MPF57/Vacc
MPF57/Unvac
FT158/Vacc
FT158/Unvacc
Bodyweight (g)
1000
900
800
700
600
500
400
300
200
100
0
a
b
c
FT158 MPF57 Unchallenged
Figure 1 - Effect of challenge virus and vaccination on chicken survival (Left, P = 0.005) and on bodyweight of
surviving chickens at 56 dpc (Right, P < 0.0001). No unvaccinated or Rispens vaccinated control
chickens died during the experiment.
The mean protective index provided by Rispens vaccine against FT158 (61%) did not
differ significantly from that provided by MPF57 (66%).
At 14 dpc, the mean body weight was 189.3 ± 15.3 g with no significant effect of
vaccination (P=0.45) or challenge (P=0.17). At 56 dpc body weight was significantly
influenced by vaccination (P