Dietary Gamma Aminobutyric Acid in Low Protein Diets Modulates Neuropeptidergic Gene Expression, Growth Performance, and Behavior in Broilers Randi Randi(a), Anisa Aulia(a), Muhtadin Muhtadin(a), Chusnul Hanim(a), Michael T. Kidd(b), Muhsin Al Anas(a),*
a)Department of Animal Nutrition and Feed Science, Faculty of Animal Science, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia
*Corresponding author: muhsin_alanas[at]ugm.ac.id
Phone: +6282226517015
b)Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, AR 72701, United States
Abstract
Low crude protein (CP) diets can improve feed efficiency and reduce ammonia emissions but may disrupt the behaviour it may negatively impact broiler productivity. This study aimed to evaluate the effects of gamma aminobutyric acid (GABA) supplementation in low CP diets on productivity, neuropeptidergic gene expression, and behavior of broilers. A total of 360 male Ross 308 broilers were used in a factorial design experiment with two CP levels (19.5 and 18.0%) and three GABA levels (0, 100, and 200 mg/kg). Result the experiment is CP and GABA levels did not significantly affect broiler productivity (P>0.05). Reducing CP in the diet increased amylase and decreased protease activities (P<0.05). GABA supplementation had no significant effect on enzyme activity (P>0.05). The expression of orexigenic genes (AgRP, NPY, ghrelin) was significantly downregulated, while anorexigenic genes (CCK, PYY, GLP-1, GLP-2) were upregulated in the 18.0% CP group (P<0.05). In contrast, dietary supplementation of GABA significantly increased the expression of orexigenic genes and decreased the expression of anorexigenic genes (P<0.05). The expression of the pro-inflammatory gene TNF-alpha was increased, while the anti-inflammatory gene IL-10 was decreased in the 18.0% CP group (P<0.05). GABA supplementation reversed this effect by downregulating TNF-alpha and upregulating IL-10 expression (P<0.05). Similarly, the expression of tight junction genes (ZO-1 and JAM-2) was decreased in broiler fed 18.0% CP, but significantly upregulated following GABA supplementation (P<0.05). A significant CPxGABA interaction was observed for orexigenic, anorexigenic, inflammatory, and tight junction gene expression (P<0.05). A 1.5% reduction in CP significant effect on decreasing feeding, drinking, and pecking (P<0.05). GABA supplementation enhanced feeding and drinking and reduced pecking (P<0.05), with a significant CPxGABA interaction effecting pecking broiler behaviour (P<0.05). A 1.5% reduction in dietar
Keywords: Broiler, low protein diet, GABA, behaviour, neuropeptidergic
