by: Dr. Taha Mohamed Alaa El-Din — Egypt

Obesity in Broiler Breeder Hens: From Excess Energy and Fat Accumulation to Cardiomyopathy, Gut Microbiota Changes, and Reduced Hatchability

The article examines the complex effects of excessive weight and fat accumulation in broiler breeder hens, emphasizing that body weight alone is not an adequate indicator of health or productivity. Excess energy intake can lead to increased liver and abdominal fat, metabolic disturbances, oxidative stress, inflammation, and cardiac damage.

Research discussed in the article shows that ad libitum feeding can increase body and liver fat while reducing egg production. Dietary composition, including moderate increases in protein and the use of certain fibers, may help reduce fat deposition. Excess energy has also been linked to cardiac lipotoxicity, oxidative stress, inflammation, and impaired heart function.
The article further explores the relationship between gut microbiota and fat metabolism, noting associations between specific bacterial genera and abdominal fat deposition, while stressing that these findings do not prove direct causation.
Most importantly, high maternal abdominal fat is associated with poorer embryonic development and hatchability. A 2026 study reported lower hatchability, more abnormal embryo positioning, and substantially higher rates of embryonic abnormalities in high-fat breeder lines.
The key message for breeders is that preventing obesity should be part of an integrated management program. Weekly body weight, flock uniformity, feed intake, target weight curves, egg production, egg weight, and body condition should be monitored together. Maintaining hens within their target weight range is important not only for productivity, but also for maternal health, reproductive efficiency, and potentially embryo and chick quality.