Impacts of a highly pathogenic ovine Eimeria ovinoidalis on the growth of Hu lambs.

The apicomplexan Eimeria ovinoidalis is distributed worldwide. It can cause clinical coccidiosis, which is one of the most pathogenic species in sheep, reducing growth rates and resulting in significant economic losses in the industry. Its principal clinical sign is profuse diarrhoea in young animals. In this study, we established a model of E. ovinoidalis infection in lambs to understand its pathogenicity and evaluate the gut microbiota and fecal metabolite profiles. Specifically, we observed a significant shift in the abundance of bacteria and disrupted metabolism in lambs. Especially during the peak period of excrete oocysts, it promoted the reproduction of some harmful bacteria in Proteobacteria and Actinobacteriota, and reduced the abundance of beneficial bacteria such as Lachnospiraceae and Rikenellaceae. In the later stage of the patent period, the abundance of harmful bacteria in the intestine decreased, the abundance of beneficial bacteria which could produce anti-inflammatory substances began to increase, and the abundance and diversity of intestinal flora also tended to parallel with the control group. Coccidia infection could lead to the increase of differential metabolites and metabolic pathways between infected and control group, but the difference decreased with time. During the peak period of excrete oocysts, although the antimicrobial metabolites such as Lividamine were up-regulated, the excess of these metabolites could still induce the production of endotoxin, while Butanoic acid and other anti-inflammatory metabolites decreased significantly. A metabolomics analysis showed that E. ovinoidalis infection altered metabolites and metabolic pathways, with biosynthesis of unsaturated fatty acids, Teichoic acid biosynthesis and Butanoate metabolism as the major disrupted metabolic pathways. Details of the gut microbiota and the metabolome after infection with E. ovinoidalis may aid in the discovery of specific diagnostic markers and help us understand the changes in parasite metabolic pathways.