Ghrelin Gene Expression in Broiler Proventriculus Tissue are Changed by Feed Restriction, Different Dietary Energy and Protein Levels

Problem statement: The aim of this study was to investigate the effects of feed restriction and different energy and protein contents of diet on ghrelin gene expression in broiler chicken. Approach: Feeding programs consisted of ad libitum and feed restriction, two energy levels (3100 and 2800 kcal ME kg^-1) and three protein levels (22.3, 19.3 and 16.3% CP). Feed restriction was applied during 22-32 days of age. Proventriculus samples were collected at 21, 32 and 49 days of age. Ghrelin mRNA expression in proventriculus tissue was quantitate using Real Time quantitative PCR. Results: We found that ghrelin gene expression was increased in restricted chicks compared with those fed ad libitum at 32 days of age (p = 0.09) but feed restriction had no effect on ghrelin gene expression at 49 days of age. A positive response in ghrelin gene expression was achieved by decreasing energy level in the diet at 21 days of age (p<0.07) and at 32 days of age (p<0.05). Also, we showed that dietary protein had no effect on ghrelin gene expression, whereas there was a tendency for an increase in ghrelin gene expression as protein decreased at total period. Conclusion: The present study, we investigated the effects of feed restriction and different energy and protein contents of the diet on ghrelin gene expression in broiler chicken. We have characterized chicken ghrelin cDNA in proventriculus tissue in broiler chicken. We also found that ghrelin gene expression is differently suppressed by diet manipulations. Additional studies are necessary to investigate the role of nutrition on ghrelin gene expression in proventriculus tissue in broiler chicken.