ABSTRACT
Eimeria oocyst populations were monitored in broiler houses on two farms during a growout and prior to the placement of new chicks on the same litter. Numbers of oocysts in litter were enumerated at Weeks 0, 5, 6, 7, and 9 and in feces at Weeks 5,6, and 7 in broiler houses with different management practices (both farms had identical coccidiostat programs but Farm A had a history of poor performance whereas Farm B had excellent performance records). On Farm A the number of oocysts in litter increased (P < .05) at the time of slaughter (Week 7) and placement of a subsequent flock (Week 9) when compared with Day 0. The number of oocysts in feces on Farm A also increased (P < .05) from Week 5 to 7. On Farm B there were no differences in numbers of oocysts in litter or feces over time. Farm B had (P < .05) lower numbers of oocysts in litter than Farm A at Week 7. The number of oocysts in feces from Farm B were consistently lower (P < .05) than Farm A at Weeks 5, 6, and 7. There were no differences in the species of Eimeria in litter between farms; however, there were differences in the species composition over time. Small (Eimeria mitis) and medium (primarily Eimeria acervulina) oocysts increased significantly over time, whereas the large oocysts (Eimeria tenella and Eimeria brunetti) and Eimeria maxima did not change over time. An increase (P < .05) in large oocysts was observed in fecal samples from Farm A over time.
