Oocyst-Shedding Patterns of Three Eimeria Species in Chickens and Shedding Pattern Variation Depending on the Storage Period of Eimeria tenella Oocysts

Abstract

Various species of Eimeria have different prepatent times and predilection sites, but their life cycles in infected poultry are similar. Practically speaking, chickens can be continuously exposed to various Eimeria species through environmental contamination. Furthermore, storage condition of the oocysts influences subsequent challenge infectivity, since coccidian oocysts contain a polysaccharide energy source known as amylopectin that is required for sporulation of oocysts and survival of the sporozoites. Here analysis of the oocyst-shedding patterns of 3 Eimeria species ( Eimeria acervulina, Eimeria maxima, and Eimeria tenella) and the effects of different oocyst storage time (64, 143, 225, and 332 days) on subsequent propagation patterns were evaluated. Based on the analysis of oocyst-shedding patterns and infectious lesions evaluated by oocyst counts and histopathology, respectively, the peak points of oocyst production and infectious lesion generation in animals infected with E. acervulina were observed to occur earlier in comparison to E. maxima- and E. tenella-infected animals. Prolonged storage of E. tenella oocysts decreased oocyst excretion (measured as oocysts per gram of feces [OPG]) and lengthened the peak period. Chickens infected with the freshest oocysts (Group A) had the highest fecal oocyst output, and animals in this group reached their peak at 7 days post-infection (dpi), which is similar to the normal pattern of oocyst output in fresh isolates. Infection with oocysts stored for longer periods showed a 1-day delay in the fecal oocyst peak count (8 dpi), and these infections also resulted in fewer OPG compared to Group A. Therefore, these results indicate that the storage period is important in affecting the peak point and pattern of oocyst shedding.

Quality traits, fatty acids, mineral content of meat and blood metabolites changes of broiler chickens after artificial infection with sporulatedEimeria tenellaoocysts

“…As shown in Figure 3, the peak faecal oocyst shedding point of E. tenella was at 7 dpi. Numbers of shedding oocysts continuously decreased after the peak-point, consistent with the results of previous studies (Cha et al 2018).…”

“…This study was divided into two parts. First, we tried to elucidate normal oocysts shedding patterns (Cha et al 2018) of E. tenella in faeces until 11 days postinfection (dpi) and identify the Eimeria strain. Second, quality traits, fatty acids, minerals and hematological alterations were conducted at 5, 7 and 9 dpi ( Figure 1).…”

Lesion Scores, Oocysts Output, Hematological and Histopathological Changes of the 7 Days Life Cycle of Eimeria Tenella in Broilers.

“…This result does not agree with Wageha Awadet al (2018) who found that oocyst shedding started at 6 dpi. There were differences of oocyst shedding because of different reproductive rates, differences in the number of schizont stages and the rate at which the stages develop (Cha et al 2018). The packed cell volumes of the infected group were signi cantly lower than in the uninfected group at 3, 4, 5, 6 and 7 dpi (p < 0.05) because blood vessels were disrupted when the schizonts mature and the merozoites were released (Hector et al 2020).…”

The impact of maturity on the ability of Eimeria acervulina and Eimeria meleagrimitis oocysts to sporulate

“…7, indicating it was definitely E. acervulina . This isolate may have been slower to complete its life cycle, or the storage period may have influenced the prepatent period, as shown for Eimeria tenella [ 1 ].…”