Effects of plant extracts against gastrointestinal nematodes of livestock: a meta-analysis

Abstract

Infestation of gastrointestinal nematodes to livestock may cause a loss in production performance and under severe condition may lead to death. This study aimed to evaluate the effects of plant extract additions on larval inhibition and mortality of gastrointestinal nematodes. A total of nine articles that comprised of 16 data points were integrated into a database. For each data point, both control and plant extract treatments were specified that included data on number of samples, mean and standard deviation. Effect size of the meta-analysis was based on Hedges’ d with the continuous random effects of DerSimonian-Laird method. Results showed that addition of plant extracts had a strong effect to inhibit larval of gastrointestinal nematodes with a cumulative effect size (95% confidence interval) of 36.6 (30.5-42.7, P<0.001). All papers supported such larval inhibition effect of plant extracts except one paper only. Further, plant extracts increased adult mortality of gastrointestinal nematodes with a cumulative effect size of 73.1 (44.6-101.7, P<0.001). In conclusion, addition of plant extracts that rich in bioactive compounds are effective to control the population of gastrointestinal nematodes. The use of plant extracts for such purpose is favorable since it is environmentally friendly.