Fig. 4. Normal appearing eggs as a percentage of the total number of recovered eggs after 1, 2, 3, 7 or 21 days of in vitro exposure to Stalosan F or commercial bird sand (control). The egg batch consisted embryonated (L 3 stage) A. galli eggs originally extracted from the uteri of female worms. The * signifies a statistically significant difference between the Stalosan F -treated and th e control group. The time of exposure to Stalosan F did not seem to have an effect since the proportion of normal appearing eggs did not change significantly during the 3 weeks of incubation in any of the four parasite egg batches. Experiment 2: Experimental infection study Only two of the 25 chickens in the group that was infected with Stalosan F -treated mixed parasite eggs were found to harbour worms when slaughtered, and each harboured only one adult A. galli . In contrast, 12 of the 25 chickens of the control group were found to harbour a number of worms, ranging from 1 to 25. The average worm burden, which was 5.3 (+/- 8.89), was found to be significantly higher (P < 0.01) compared to the average worm burden of 0.08 (+/- 0.28) in the group infected with Stalosan F - treated eggs. Fig. 5. The average number of A. galli found at the time of slaughter in two groups of 25 chickens. Both groups had been placed in a pen contaminated wit h A. galli eggs for 6 weeks prior to slaughter. One group was confined to half of the pen which was treated wit h Stalosan F on a weekly basis. The other group was confined in the other half of the pen which was left untreated as control.
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