Overfeeding-induced ovarian dysfunction in broiler breeder hens is associated with lipotoxicity

In mammals, triacylglycerol (TAG) accumulation in nonadipose tissue, termed lipotoxicity, develops with obesity and can provoke insulin resistance, overt diabetes, and ovarian dysfunction. Leptin, an adipose tissue hormone, may mediate these effects. Feed-satiated broiler breeder hens manifest lipotoxicity-like symptoms. Changes in body and organ weights, hepatic and plasma TAG, nonesterified fatty acids (NEFA), ovarian morphology, and egg production in response to acute voluntary increases of feed intake were measured in 2 studies with Cobb 500 broiler breeder hens provided with either 145 or >= 290 g of feed/d per hen for 10 d. In both studies, no hen fed 145 g of feed/d exhibited ovarian abnormalities, whereas similar to 50% of feed-satiated hens did. Egg production in feed-satiated hens was reduced from 73.3 to 55.8% (P = 0.001). Morphology indicated that apoptosis-induced atresia occurred in the hierarchical follicles. Fractional weight of yolk increased from 29.3 to 30.6% (P = 0.016) and no longer correlated to egg weight. Body, liver, and abdominal adipose weights were significantly greater (P < 0.05) in feed-satiated hens, as were plasma concentrations of glucose, NEFA, TAG, insulin, and leptin (P < 0.05). Feed-satiated hens with abnormal ovaries had significantly more liver and abdominal fat, greater plasma leptin and TAG concentrations, and more saturated fatty acids in plasma NEFA than did feed-satiated hens with normal ovaries. Differences in severity of lipotoxic metabolic and hormonal responses among feed-satiated hens were closely linked to the incidence of ovarian abnormalities and granulosa cell susceptibility to apoptosis and necrosis.