Two battery efficacy studies were conducted with field isolates of Eimeria spp. from outbreaks of coccidiosis on pheasant-rearing farms in Georgia (GA) and Illinois (IL), United States. The coccidian isolates were mixed species containing E. phasiani, E. duodenalis, and E. colchici. Lasalocid (LAS) was tested prophylactically at 120 parts per million (ppm) in the feed. Anticoccidial activity was assessed, in comparisons between infected and uninfected control birds, by the effects on weight gain and oocyst passage. The GA isolate reduced weight gain of infected controls by 64% (P < 0.05) during the week after inoculation. LAS-treated birds also suffered some depressed gain, but average gains were significantly improved (P < 0.05) in comparison with that of the infected controls. Fecal oocyst counts of infected controls averaged 10–24 × 106/day for days 5–11 postinoculation (PI), after which oocyst passage declined. Birds given LAS passed 10–20 × 106 oocysts on days 5–6 PI, after which counts dropped to much lower levels. Oocyst passage was significantly reduced (P < 0.05) by LAS treatment on all but days 5 and 6 PI. The IL isolate reduced weight gain by 36% in infected controls, relative to uninfected controls (P < 0.05). LAS-treated birds also suffered reduced gain, but the gain was significantly improved in comparison with the infected controls. Oocyst counts averaged 3–9 × 106/day on days 6–14 PI, but were significantly reduced by LAS treatment on all but day 6 PI. Thus, LAS was effective in pheasants against the tested field isolates of Eimeria spp. and was well tolerated at 120 ppm in the feed. However, the level of control was not as high as previously observed. Possible explanations for this difference include an emergence of drug resistance from prior use of LAS and a differential efficacy of LAS against different species of Eimeria used in the studies.
Abbreviations: GA = Georgia; IL = Illinois; LAS = lasalocid; PI = postinoculation; ppm = parts per million
Eficacia del Lasolacid contra la coccidiosis en faisanes Chinos de cuello anillado.
Se realizaron dos estudios de eficacia con aislamientos de Eimeria provenientes de brotes de coccidiosis en granjas de cría de faisanes en los estados de Georgia e Illinois en los Estados Unidos. Los aislamientos de coccidia representaron una mezcla de especies: E. phasiani, E. duodenalis y E. colchici. El Lasolacid se ensayó profilácticamente en el alimento a una dosis de 120 partes por millón (ppm). La actividad anticoccidial se evaluó mediante la comparación de los efectos de las coccidias en la ganancia de peso y en la tasa de eliminación de ooquistes en aves control infectadas y no infectadas. El aislamiento de Georgia redujo la ganancia de peso de los controles infectados en un 64% (P < 0.05) durante la primera semana post-inoculación. Las aves tratadas con Lasolacid también sufrieron alguna depresión en la ganancia de peso, sin embargo, el promedio de las ganancias se mejoró significativamente (P < 0.05) en comparación con la ganancia de los controles infectados. Los recuentos de ooquistes fecales de los controles infectados promediaron 10–24 × 106 ooquistes por día los días 5 a 11 post-inoculación, después de este periodo la eliminación de ooquistes declinó. Las aves tratadas con Lasolacid eliminaron 10–20 × 106 ooquistes por día entre los días cinco y seis post inoculación, luego de los cuales los recuentos disminuyeron a niveles mucho más bajos. La eliminación de ooquist
