Effect of Feed Restriction and Dietary Fat Type on Liver Fatty Acid Binding Protein mRNA Expression in the Broiler Chickens Bahman Navidshad Department of Animal Science, University of Mohaghegh Ardabili, Ardabil, Iran Email: bnavidshad@uma.ac.ir Maryam Royan Agricultural Biotechnology Research Institute of Iran- North Branch, Rasht, Iran Email: m_royan2002@yahoo.com Abstract—Liver fatty acid binding protein (L-FABP) is the main cytosolic binding site for long chain fatty acids in hepatocytes. FABPs enhance uptake of fatty acids into the cell by increasing their concentration gradient, due to minimizing unbound fatty acid in the cell. A total of 720, 10- day old male Ross 308 broiler chicks were fed diets with unsaturated to saturated fatty acid ratio (U/S) of 2, 3.5, 5 or 6.5 as ad lib or skip a day feeding schedule (during 18-28 days of age). The results clearly showed that feed restriction induced L-FABP gene expression in the livers of broiler chickens. The L-FABP gene expression increased by dietary unsaturated to saturated fatty acid ratio of 6.5. No interaction of dietary U/S and feed restriction on the liver L- FABP gene expression was observed. This observation proposes that birds have a mechanism for regulation of fatty acids transfer under different nutritional condition. Index Terms— dietary U/S, broiler chickens I. INTRODUCTION Because of limited capacity of digestive tract, plant or animal fats or their mixtures are important components of broilers high-energy diets. Fats with high-unsaturated fatty acid content have a more absorbability and there is a known synergism between saturated and unsaturated fats [1], [2]. Age of birds affects fat digestibility too, because at earlier ages, there is an inadequate production of fat digestive enzymes from liver [3]. Fat metabolism is under exact control and several genes are involved. The intracellular fatty acid-binding proteins (FABPs) comprise a family of 14-15 kDa proteins which bind long-chain fatty acids [4], [5]. Members of this family have been evolved over approximately one billion years by subsequent duplication and diversification of an ancestral intracellular lipid binding protein gene, thereby generating a large number of tissue-specific homologs [6]. The FABPs may modulate lipid metabolism via an involvement in the fatty acid uptake or export process, by Manuscript received March 25, 2015; revised July 2, 2015. regulation of substrate and/or product concentrations in the cytosolic compartment as a whole or more locally near particular enzymes, and/or by specifically delivering or removing fatty acids to/from particular enzymes [7]. FABPs enhance uptake of fatty acids into the cell by increasing their concentration gradient, due to minimizing unbound fatty acid in the cell [8]. It is suggested that L-FABP may function in the partitioning of fatty acids to different lipid metabolic pathways [6]. The control of tissue-specific expression of the various FABP types is only poorly understood. Often, the expression of FABPs in a given tissue reflects its lipid metabolizing capacity and increased fatty acid exposure leads to a marked increase in FABP expression [9]. Liver have a important role in fatty acid absorption [10], [11], directing fatty acids to particular metabolic pathways [6], lipoprotein synthesis [12] and transport of peroxisome proliferator-activated receptor ligands to the nucleus and consequential modulation of target-gene expressions [13]. The basic liver type fatty acid binding protein (Lb- FABP) is the only FABP that is not expressed in mammals. It is found in the liver of birds, fish, reptiles, and amphibians [14]. In chickens, the Lb-FABP gene is expressed only in the hepatocytes, whereas the L-FABP expression is done in both liver and intestinal tissues [15]. In the Ref [15], only little amounts of the L-FABP and Lb-FABP mRNAs were identified in the liver during chicken embryogenesis, but at the onset of hatching a remarkable increase in mRNA expression was detected for both genes, suggesting that the expression of the L- FABP and Lb-FABP genes is coordinated at developmental stages [15]. The L-FABP expression alters by a number of factors that greatly impact hepatic fatty acid metabolism, including feed restriction, high-fat diets and peroxisome proliferators [16], [17]. Ref [18] showed a dose- dependent increase in L-FABP gene expression of the chickens fed soybean lecithin. Ref [19] showed that feed restriction reduced the expression of genes involved in lipogenesis, but enhanced 15 © 2016 Journal of Advanced Agricultural Technologies doi: 10.18178/joaat.3.1.15-19 Journal of Advanced Agricultural Technologies Vol. 3, No. 1, March 2016 L-FABP, real time PCR, feed restriction,