Evaluation of the Anticoccidial Activity of Sheep Bile against Eimeria stiedae Oocysts and Sporozoites of Rabbits: An In Vitro Study

SIMPLE SUMMARY: Coccidiosis is a common disease that infects rabbits, causing substantial problems, such as severe diarrhea, feces containing mucus or blood, weight loss, reduced reproductivity, and a high death rate. The widespread use of the currently available anticoccidial drugs has led to widespread drug resistance, prompting the search for alternative drugs. The bile of animals, such as poultry, cattle, sheep, etc., is a promising candidate for alternative bile-related therapeutic strategies. This study highlights the potential of sheep bile as an anticoccidial agent by demonstrating its capacity to inhibit the sporulation of coccidian oocysts, as well as its anti-sporozoite activity. ABSTRACT: Coccidiosis is one of the most common infectious diseases that causes digestive problems in rabbits, leading to global economic losses. This study was conducted to evaluate the effects of bile obtained from sheep gallbladder on the sporulation and morphology of Eimeria stiedae oocysts and sporozoites affecting rabbit liver cells and to determine the best concentration for sporulation inhibition. Sporulation inhibition per milliliter was measured in samples exposed to five concentrations of sheep bile (SB) in a 2.5% potassium dichromate solution: 12.5%, 25%, 50%, 75%, and 100% concentrations for oocysticidal activity and 125, 250, 500, 750, and 1000 μg/mL concentrations for antisporozoidal activity. A bioassay was performed to assess the in vitro anticoccidial activity of sheep bile against E. stiedae oocysts and sporozoite sporulation. In this assay, six-well plates with 5 mL of bile containing 1000 oocysts showed unsporulated oocysticidal activity after 48, 72, and 96 h and antisporozoidal activity after 12 and 24 h. A chemical assay was performed via infrared spectroscopy to investigate the presence of several anticipated active chemical compounds in sheep bile. Sheep bile was able to inhibit E. stiedae oocysts at 100% and 75% concentrations by about 91% and 81%, respectively. In addition, SB had the highest inhibition of E. stiedae sporozoite viability (92%) at a concentration of 1000 μg/mL and had the lowest inhibition of 8% at a concentration of 125 μg/mL. An increase in the incubation time and a higher dose generally increased the inhibition rate. The results showed that sheep gallbladder bile is effective due to its inhibitory potential and effect on the coccidian oocyst sporulation of E. stiedae. Further studies are needed to determine the precise active chemicals present in SB and their modes of action and application in vivo.