Efficacy of powdered leaf and flower of Lobelia decurrens Cav. to control coccidiosis in calves

Background: Cattle are susceptible to infections by parasitic protozoa, which often require chemical treatments. However, using these products can contaminate the soil and negatively affect flora and fauna, leaving residues in milk and meat, posing a consumer risk. Therefore, it is crucial to seek less harmful alternatives to the environment, such as using bioactive plants. This study aimed to evaluate the efficacy of the pulverized plant contoya (Lobelia decurrens Cav.) at two doses (1 g/kg vs. 2 g/kg) in controlling coccidiosis in naturally infected heifers under extensive rearing conditions. Methods: Groups of heifers with similar parasitic loads (ANOVA p>0.05) were formed and orally administered to the pulverized leaves and flowers of the contoya plant. Efficacy was calculated as the percentage reduction of oocysts per gram of feces using a McMaster chamber. Results: The 2 g/kg dose significantly reduced the parasitic load compared to the 1 g/kg dose (p<0.05). With a dose of 1 g/kg, a minimum efficacy of 38.04% was observed on the third day and a maximum efficacy of 86.93% on the fifteenth day. With the 2 g/kg dose, a minimum efficacy of 73.91% was achieved on the third day and a maximum efficacy of 95.45% on the fifteenth day. Conclusions: These results indicate that the use of contoya at a dose of 2 g/kg can be an effective option for controlling coccidiosis in heifers. This could be advantageous for small-scale cattle producers, providing an alternative to conventional drugs in terms of costs and environmental impact.