Exploring the Impact of Metformin on Broiler Breeder Hens

A surge of research is revealing new applications for established medications across various species. One notable example is metformin, a widely used drug for managing type 2 diabetes and polycystic ovary syndrome (PCOS) in humans. Recent findings indicate that metformin may significantly enhance reproductive health and productivity in broiler breeder hens.

The Challenges of Broiler Breeder Hens

Broiler breeder hens are specifically selected for their ability to produce rapidly growing meat chickens. However, the intense genetic selection for accelerated growth has brought about unintended reproductive issues. Many of these hens experience ovarian dysfunction characterized by excessive follicular recruitment, disrupted hormone levels, and a decline in egg production and fertility—conditions mirroring PCOS in women.

Research Study Overview

To evaluate the potential benefits of metformin on these reproductive challenges, researchers conducted a comprehensive 40-week study involving 180 hens. The hens were split into four groups, each receiving diets supplemented with varying doses of metformin: 0, 25, 50, or 75 mg/kg body weight.

Key Findings

The study yielded several significant and multifaceted outcomes, revealing numerous physiological improvements in the metformin-treated hens:

• Body Weight and Fat Reduction: Hens receiving the highest dose of metformin (75 mg/kg) exhibited notably reduced body weight and abdominal fat pad mass. This suggests that metformin may play a role in controlling excessive weight gain, which is detrimental to reproductive health.
• Restoration of Normal Ovarian Function: Untreated hens exhibited abnormal numbers of large yellow follicles (LYFs), indicating over-recruitment of follicles. Metformin supplementation, especially at higher doses, helped restore a more natural follicular hierarchy, essential for regular ovulation and egg laying.
• Improved Egg Production and Hatchability: Hens treated with 50 or 75 mg/kg of metformin laid significantly more eggs and showed improved fertility and hatchability rates, particularly at 65 weeks of age, a period typically marked by declining reproductive performance.
• Hormonal Balance: Metformin treatment impacted circulating reproductive hormone levels, notably decreasing plasma testosterone and the testosterone-to-androstenedione ratio. Elevated testosterone is often linked to reproductive dysfunction; thus, this hormonal shift likely played a crucial role in restoring ovarian activity.
• Upregulation of Key Ovarian Genes: The treatment led to enhanced expression of genes involved in steroidogenesis in theca cells, such as STAR, CYP11A1, HSD3B1, and CYP17A1, which are essential for the synthesis of sex steroids and overall ovarian function.

The Significance of the Findings

The implications of this study are invaluable for the poultry industry. Subfertility in broiler breeder hens can lead to decreased egg production and hatchability, directly impacting commercial efficiency. Integrating metformin into feeding regimens could offer a straightforward, non-invasive method to enhance reproductive performance while ensuring animal welfare.

This research also underscores the physiological similarities in reproductive disorders across different species. By using hens as a model, researchers can study PCOS-like conditions, opening new avenues for both agricultural and biomedical research.

Future Directions

Further studies are essential to optimize metformin dosing, evaluate long-term safety, and delve deeper into the underlying molecular mechanisms. Nonetheless, this research illustrates the potential of repurposing well-established human medications to tackle complex challenges in animal agriculture.

By harnessing insights from cross-species research, metformin may not only become a critical tool in managing chronic conditions in humans but also enhance the health and productivity of vital food-producing animals.

Source: National Library of Medicine