Table 1.
Rearing conditions during field surveys: detailed conditions used in the three field surveys including flock information, biosecurity, feed additives used, and antibiotic therapy.
| Type of Condition | Field Survey 1 | Field Survey 2 | Field Survey 3 |
|---|---|---|---|
| flock information | |||
| flock size | 33,000 | 33,000 | 33,000 |
| breed | Ross 308 | Ross 308 | Ross 308 |
| season | June–August | August–September | October–November |
| biosecurity | |||
| rubber boots | changed | Changed | changed |
| clothes | not changed | not changed | not changed |
| prethinning | yes | Yes | yes |
| vaccination (first 15 days of life) | Gumboro disease, Newcastle disease, Infectious bronchitis | Gumboro disease, Newcastle disease, Infectious bronchitis | Gumboro disease, Newcastle disease, Infectious bronchitis |
| feed additives | |||
| first 18 days of life | vitamins A, D3, E 1 | vitamins A, D3, E 1 | vitamins A, D3, E 1 |
| whole rearing period | buffered acids * | buffered acids * | buffered acids * |
| antibiotic therapy | amoxicillin/colistin on days 33–35 | lincomycin-spectinomycin on days 1–4 | lincomycin-spectinomycin on days 1–4 |
1 applied via the drinking water several times over two to three days; * a commercially available product, applied via the drinking water repeatedly during the whole rearing period, not applied during antimicrobial treatment and vaccination.