ABSTRACT The aim of this study was to investigate the effects of different dietary levels of L-arginine on the growth performance, blood parameters, and lipogenic gene expression of Arian broiler chickens. For this purpose, 168 Arian broiler chicks (40.33±1.7 g) were assigned to four treatments with three replicates of14 birds each, according to completely randomized design. The experimental treatments consisted of 100, 124, 139, and 154% dietary arginine levels relative to the published requirements of Arian broilers. On 42 d of the experiment, blood samples were collected from two birds (six birds per treatment) for blood metabolite measurements. These birds were then euthanized for carcass evaluation and collection of tissue samples. Increasing dietary arginine levels reduced (p<0.05) the gene expression of fatty acid synthase, acetyl-coenzyme A carboxylase, and malic enzyme in the liver and lipoprotein lipase in the abdominal fat tissue, as well as abdominal fat relative weight. Increasing dietary arginine levels significantly increased (p<0.05) body weight, feed efficiency, carcass yield, breast and thigh relative weights, and glucose and HDL (high-density lipoprotein) blood levels, and reduced cholesterol, triglyceride, and LDL (low-density lipoprotein) blood levels. Since almost similar performance and carcass trait results were obtained both with 124 and 139% arginine levels, supplying Arian broiler diets with 124% arginine is suggested.

ABSTRACT Feeding behavior is regulated via a complex network which interacts via diverse signals from central and peripheral tissues. Endocannabinoids modulate release of GABA in a variety of regions of the central nervous system. Endocannabinoids and GABAergic system have an important role in the central regulation of appetite. Thus, the present study examines the possible interaction of central canabinoidergic and GABAergic systems on food intake in 3-h food-deprived (FD3) neonatal layer-type chicks. The results of this study showed that intracerebroventricular (ICV) injection of 2-AG (2-Arachidonoylglycerol, selective CB1 receptors agonist, 2µg) significantly increased food intake and this effect of 2-AG was attenuated by Picrotoxin (GABAA antagonist, 0.5µg) (P<0.001); but 21ng CGP54626 (GABAB antagonist) had no effect (p>0.05). Also, hyperphagic effect of CB65 (CB2 receptors agonist, 1.25µg) was not affected by Picrotoxin or CGP54626 (p>0.05). Moreover, the food intake of chicks was significantly increased by ICV injection of GABAA agonist (Gaboxadol, 0.2 µg) and SR141716A (CB1 receptors antagonist, 6.25µg) significantly decreased Gaboxadol-induced hyperphagia (P<0.001) but CB2 receptors antagonist (AM630, 1.25µg) had no effect. In contrast, co-injection of SR141716A or AM630 with GABAB agonist (baclofen, 0.2µg) had no effect on the hyperphagia induced by baclofen (p>0.05). These data showed there might be an interaction between central cannabinoidergic and GABAergic systems via CB1 and GABAA receptors in control of food intake in neonatal layer chicks.