Impact of Pesticides on Reproductive Health in Poultry: A Comprehensive Study

In recent years, the adverse effects of high pesticide doses on biological systems have garnered increasing attention. This includes significant concerns about reproductive health in mammals and birds. The widespread use of pesticides, including fungicides, insecticides, and herbicides, contributes to the contamination of animal feed, exposing poultry to these harmful substances. Numerous pesticides, including those approved for use in organic farming systems, as well as synthetic compounds, leave behind persistent residues.

To address the growing concerns about food and feed safety, the European Union has implemented stringent regulations regarding pesticide usage. These include directives establishing maximum residue levels (MRLs) in cereals, vegetables, fruits, and animal-derived products. MRLs are based on empirical data for each type of crop or animal product, dictating the legal limits for pesticide residues in food or feed when products are used according to the recommended doses specified on the label. The EU REACH Regulation further mandates the registration and thorough assessment of chemical substances, ensuring that broader risks to humans and the environment are evaluated.

This study focuses specifically on three pesticides—tebuconazole, glyphosate, and imidacloprid—selected for their extensive agricultural use, environmental persistence, and increasing evidence of negative effects on reproductive health, even at low exposure levels.

Methological Framework

Selected Pesticides

Tebuconazole (TEB) is a triazole fungicide known for inhibiting sterol biosynthesis in fungi. However, it shows poor biodegradability, making it a long-lasting contaminant in soil and food products. TEB has been linked to endocrine disruption, leading to reproductive and developmental toxicity. Toxicological studies indicate that perinatal exposure to TEB can result in significant anomalies, including masculinization in females.

Imidacloprid (IMI), a neonicotinoid insecticide, is known to target nicotinic acetylcholine receptors in insects. Its persistent nature means it accumulates in soil, water, and plants. Despite being selective for insect receptors, studies show it negatively impacts the mammalian reproductive system, causing disrupted spermatogenesis and reduced ovarian morphology.

Glyphosate (GLP) is a broad-spectrum herbicide effective against a variety of weeds. While its relatively low environmental persistence is noted, repeated applications can lead to cumulative risks. Studies have shown that glyphosate may disrupt hormonal functions and even impact sperm motility.

Aim of the Study

The primary purpose of this research was to evaluate the impacts of six weeks of dietary exposure to low, sublethal doses of TEB, IMI, and GLP on the reproductive performance of roosters. We specifically assessed various reproductive metrics, including semen quality, fertilization and hatchability rates, embryonic mortality, and presence of pesticide residues in blood, semen, and tissues.

Material and Methods

Chemicals Used

The substances used in this experiment were sourced from reputable commercial suppliers. The pesticides included Roundup 360 Plus (glyphosate), Orius Extra 250 EW (tebuconazole), and KOHINOR 200 SL (imidacloprid).

Feed Preparation

The levels of pesticides in the feed were derived from MRLs, ensuring realistic exposure scenarios for the poultry. Stock solutions were prepared from the commercial formulations and subsequently incorporated into the feeds.

Animal Description

The study involved 80 roosters of the Green-legged Partridge breed, reared under controlled conditions. Each bird was housed individually, allowing for detailed monitoring of their behavior and physiological parameters.

Experimental Design

Roosters were divided into eight groups, each receiving a different dietary regimen—some with pesticide exposure and one control group. After six weeks, a four-week washout period was observed, followed by gathering data on fertility and other reproductive metrics.

Results

Findings indicate that even within regulatory limits, chronic exposure to pesticides adversely affected key reproductive endpoints. Impairments in sperm functionality, decreased fertilization success, and higher embryo mortality were recorded. These reproductive effects often correlated with measurable pesticide residues in various bodily fluids and tissues.

Effects of Individual Pesticides

Among the chemicals studied, TEB exposure significantly influenced reproductive results, particularly affecting hatchability rates. IMI and GLP, while presenting a somewhat delayed effect, also raised concerns. The study concluded that combined pesticide exposure typically exacerbated these adverse effects on sperm quality and reproductive capacity.

Considerations and Conclusions

This research underscores that regulatory frameworks may underestimate the biological consequences associated with chronic pesticide exposure. The durability of pesticide residues in poultry tissues and the potential for long-term effects on reproductive health necessitate a reevaluation of current safety margins for pesticide use, particularly endocrine disruptors.