Effect of short- and long-term feed restriction on ghrelin concentrations in turkeys

One-day-old broad-breasted white turkeys (Meleagris gallopavo) were reared as recommended by industry standards. In Experiment 1, starting at 5 wk of age (WOA), birds were placed in individual cages with free access to feed and water. Blood samples were taken after 18 h of fasting (FASTING) and at 90 ± 5 min after feeding (1.5 h after feeding). In Experiment 2, birds were weighed, randomly assigned to 2 treatments, and placed in individual cages. In treatment 1 (n = 10), birds were fed ad libitum (FF), while birds in treatment 2 (n = 11) were placed on a restricted diet to allow for an average daily gain of 10.0 g per d from 4 to 11 WOA (RES). In Experiment 1, concentrations of ghrelin (P = 0.012) and glucose (P < 0.001) were increased 1.5 h after feeding compared with concentration during FASTING, whereas concentrations of adrenocorticotropic hormone (ACTH) (P < 0.001) and corticosterone (P = 0.002) were decreased 1.5 h after feeding. Concentration of insulin, free fatty acids, and ketone bodies followed a normal physiological response to fasting and feeding. Similarly, in Experiment 2, concentrations of ghrelin (P < 0.001) and glucose (P = 0.038) were increased in FF birds, whereas concentrations of corticosterone were decreased (P = 0.002) in FF birds. It could be concluded that in turkeys, preprandial (18 h of fasting) and long-term feed restriction is associated with decreased concentration of ghrelin-thus, the opposite effect of that reported in chickens and mammalian species.