Dietary n-3 and n-6 Fatty Acids Alter Avian Pituitary Sensitivity

The effects of dietary saturated and polyunsaturated fatty acids (PUFAs) of the n-3 and n-6 series on avian pituitary sensitivity were investigated by infusing human growth hormone (GH) releasing hormone - fragment 1-29 - and chicken luteinising hormone releasing hormone (LHRH) into catheterized broiler chickens. At 3 weeks of age three groups (n=18; six birds per group) were fed for 6 weeks isonitrogenous and isoenergetic experimental diets containing 80 g/kg of edible tallow (saturated fatty acids), fish oil (n-3 PUFAs) or sunflower oil (n-6 PUFAs). Jugular catheterisation was performed under general anaesthesia during week four of the dietary treatments and the birds allowed 7 days post surgery to recover. A bolus of LHRH (20 b.mug/bird) and a GH releasing hormone (12.5 b.mug/kg) infusion was given on different days to each chicken and serial blood samples taken over a 1 h period. Plasma luteinising hormone and GH concentrations were measured by radioimmunoassay. Pre-infusion GH concentrations were similar for the tallow, fish and sunflower oil dietary groups (5.2±3.9, 5.2±1.0 and 6.1±3.1 ng/ml, respectively), however, GH concentration in response to the GH releasing hormone infusion was elevated in the sunflower oil group (44.7±5.7 ng/ml) when compared to chicken fed tallow (33.7±9.7 ng/ml) or fish oil (21.3±5.0 ng/ml). There was a significant decrease (