Dietary exposure to pesticides in poultry: From semen quality to embryonic mortality and tissue accumulation

The widespread use of pesticides in agriculture increases the risk of chronic dietary exposure in poultry. This study investigated the effects of low-dose exposure to tebuconazole (TEB), imidacloprid (IMI), and glyphosate (GLP), administered individually or in combination at concentrations not exceeding maximum residue limits (MRLs), on male reproductive performance in Gallus gallus. Roosters were assigned to eight groups and exposed for six weeks (Phase I), followed by a four-week pesticide-free recovery period (Phase II). Sub-MRL pesticide exposure impaired male reproductive function, with the most pronounced effects observed following combined treatments. During Phase I, exposure resulted in reduced semen quality, decreased fertility and hatchability, and increased embryo mortality, particularly in groups receiving IMI alone or in combination. These functional impairments were accompanied by detectable pesticide residues in reproductive tissues and body fluids, as well as modulation of local and systemic immune parameters. During Phase II, semen parameters showed partial recovery toward control levels; however, fertility and hatchability remained reduced in several groups, coinciding with the persistence of pesticide residues in semen and selected tissues. Combined pesticide exposure consistently produced stronger and more persistent reproductive effects than individual compounds, indicating mixture-specific toxicity and incomplete reversibility. Collectively, these findings demonstrate that chronic exposure to MRL-compliant pesticide doses can compromise avian reproductive performance, particularly under combined exposure scenarios. The persistence of residues in reproductive compartments and excreta further highlights potential environmental and biological risks, supporting the need to consider reproductive endpoints and chronic mixture exposure in pesticide risk assessment frameworks.