In Vitro Evaluations and Comparison of the Efficacy of Two Commercial Products Containing Condensed Tannins and of Saifoin (Onobrychis viciifolia Scop.) Hay against Gastrointestinal Nematodes of Goats

Abstract

Gastrointestinal nematodes (GINs) is a limiting health factor for dairy goats, and the integration of the diet with fodder containing condensed tannins (CT) is becoming increasingly important to control GINs. To preliminary evaluate their potential role as part of GIN control in goat breeding, the in vitro anthelmintic efficacy of the CTs of Silvafeed BYPRO (SBP), Silvafeed Q powder (SQ), and sainfoin hay (SH) was evaluated, and the untargeted metabolomics profiling of the selected formulations was performed. CTs were extracted in water and in ethanol, their concentration was determined, and their chemical characterization was conducted using High-Performance Liquid Chromatography (HPLC) coupled to High-Resolution Mass Spectrometry (HRMS) platform. The in vitro anthelmintic activity of the extracts was evaluated using the Eggs Hatch Test (EHT) and the Larval Migration Inhibition Test (LMIT) using different extract concentrations (150, 300, 600, and 1200 μg/mL). The metabolomic profile of the ethanol extract showed a high number of flavonoids, while the water extract showed higher levels of hydrolysable tannins. The ethanol extracts were effective on both eggs hatching and larvae migration at low concentrations (150 μg/mL) for the three analyzed samples, while the water extracts showed more varied results: SH showed the greatest ovicidal efficacy (concentration 150 μg/mL, %IH = 40.9), while SBP and SQ were more effective against the larvae migration (concentration 600 μg/mL, %LMI = 69.7% and 88%), respectively. The integration of CT-rich fodder into the diet may be considered for the control of GIN infection in goats.

Keywords: Eggs Hatch Test (EHT); Larval Migration Inhibition Test (LMIT); condensed tannins; gastrointestinal nematodes.

Figure 1

Hierarchical cluster analysis for the 45 most abundant species of flavonoids identified in ethanol extracts. Heatmap reflects the differences between the relative amount through normalized chromatographic peak areas in respect to sample type; z-color scale indicates normalized peak area value: red and green indicates more and less abundant, respectively.

Figure 2

Hierarchical cluster analysis for the 55 most abundant species of hydrolysable tannins identified in water extracts. Heatmap reflecting the differences between relative amount through normalized chromatographic peak areas in respect to sample type; z-color scale indicates normalized peak area value: red and green indicates more and less abundant, respectively.

Figure 3

Percentage of inhibition of egg hatching with various concentrations of the tested extracts (%IH). Compared to phosphate buffer saline (PBS) and thiabendazole, %IH of PBS (negative control): 0%, %IH of thiabendazole (positive control): 97.3%. The significant inhibitory effects (p-value < 0.05, one-way analysis of variance, followed by Dunnett’s post hoc test) are indicated with *. Each bar represents mean ± standard error of the mean. (A–C) = H₂O (water) extracts; (D–F) = EtOH (ethanol) extracts.

Figure 4

Percentage of inhibition of larval migration with various concentrations of the tested extracts (%LMI). Compared to phosphate buffer saline (PBS), levamisole, or polyvinylpolypyrrolidone (PVPP). %LMI of PBS (negative control): 47%, %LMI of levamisole (positive control): 100%. The significant inhibitory effects (p-value < 0.05, one-way analysis of variance, followed by Dunnett’s for PBS and by Tukey’s post hoc test for PVPP) are indicated with *. Each bar represents mean ± standard error of the mean. (A–C) = H₂O (water) extracts; (D–F) = EtOH (ethanol) extracts.