Essential oil spraying enhances sperm kinetics and reduces aggressive behavior in boars

The study was conducted at a semen processing center with the aim of evaluating the effects of spraying essential oils with anxiolytic properties on the productivity, welfare, and health parameters of breeding boars. Fifty boars from two commercial genetic lines (average age 527 days) were used in a crossover design with two treatments.: (1) Control (CON) - placebo solution spray; and (2) Essential Oils (EOIL) - daily spray of lavender (Lavandula angustifolia) and sweet orange (Citrus sinensis) essential oils. Solutions were sprayed on the animals' heads for 10 min daily over 45 consecutive days per round. Health, behavior, and semen quality were evaluated throughout the experimental period. Daily spraying of lavender and sweet orange essential oils significantly improved sperm kinetics, increasing curvilinear displacement (DCL: 112.68 μm vs. 106.75 μm; P = 0.0046), average path displacement (DAP: 61.68 μm vs. 59.09 μm; P = 0.0197), straight line displacement (DSL: 45.61 μm vs. 42.92 μm; P = 0.0417), curvilinear velocity (VCL: 182.43 μm/s vs. 172.89 μm/s; P = 0.0051), average path velocity (VAP: 100.86 μm/s vs. 96.25 μm/s; P = 0.0162), and straight-line velocity (VSL: 76.07 μm/s vs. 71.31 μm/s; P = 0.0288). No alterations were observed in general activity or stereotypical behaviors, but treated boars showed lower lesion scores on the anterior body region (P = 0.002), suggesting fewer aggressive or stall-bar-directed interactions. Treated animals also exhibited a slight reduction in positive investigative contacts with neighboring boars (P = 0.0063). Thus, although behavioral changes were subtle and primarily reflected reduced social conflict indicators, essential oil spraying contributed to physical well-being and improved sperm kinematic parameters.