Effects of rotational poultry grazing on herbaceous vegetation and NIRS characteristics in Mediterranean olive agroecosystems

Silvopastoral systems in Mediterranean olive groves offer a promising strategy to enhance environmental and economic sustainability. Among livestock species suitable for silvopastoral systems, poultry husbandry is gaining interest among olive growers due to its adaptability and potential to complement olive cultivation. Rotational grazing offers a sustainable alternative to continuous grazing by moving animals between pastures, reducing pressure and allowing vegetation to recover. However, its effects in poultry-based systems remain underexplored. This study evaluates the impact of rotationally grazed laying hens on vegetation and forage quality within an organic olive grove. We compare vegetation across three spatial contexts—open grassland (FrGr), shaded areas beneath the olive canopy (OlGr), and ungrazed control plots (NoGr)—assessing biomass production, botanical composition, and forage quality using NIRS. Egg production was monitored in relation to the grazing context. The trial was conducted over two years (2023–2024) at the Triboli Farm in central Italy. A clear year-to-year variation in biomass was observed. In 2023, OlGr showed lower biomass, while in 2024 biomass increased across all treatments. Poaceae dominated, while Fabaceae declined across years and treatments. NIRS analysis showed limited nutritional differences; only ash content was significantly higher in OlGr. Egg production followed a seasonal pattern, with no significant effect of year or biomass on egg output. Rotational poultry grazing can be successfully integrated into Mediterranean olive systems, promoting pasture recovery and system multifunctionality. However, outcomes differ across microhabitats, highlighting the need to maintain plant diversity and apply targeted management strategies to sustain both biomass and ecological balance.