Endocrine responses to short-term feed deprivation in weanling pigs.

The study objective was to assess endocrine and tIssue responses to feed deprivation in weaned pigs. In experiment 1, eight crossbred castrated male pigs were either fed on a continual basis (CON; n=4) or were feed deprived for 24 h and then re-fed until 30 h (FD; n=4). Relative serum concentrations of ghrelin tended to be lower in FD pigs at 12 h (P=0.08) when compared with CON pigs, but was higher at 24 h and 30 h compared with 12 h (P<0.05). Serum IGF-I was lower in FD pigs from 12 to 30 h as compared with CON pigs (P<0.05) and increased following re-feeding (P<0.06). Experiment 2 consisted of 32 pigs that were either fed for 72 or 96 h (CON72 and CON96; n=16), feed deprived for 72 h (FD72; n=8), or FD72 and then re-fed from 72-96 h (FD72/RF24; n=8). Ghrelin in the FD72 and FD72/RF24 groups was lower at 12 h (P<0.03) compared with CON pigs, but then increased from 12 h to 36 h (P<0.01). Serum IGF-I and leptin decreased following feed deprivation (P<0.001) and remained low until re-feeding. Cortisol was elevated from 12 h to 72 h during feed deprivation (P<0.01) but was not different from CON96 pigs following refeeding (P>0.88). Expression of ghrelin mRNA tended to be lower in the FD72 pigs' stomachs, pituitary glands, and hypothalami (P=0.06, 0.07, and 0.08 respectively) compared with CON pigs. These results provide evidence that feed deprivation is accompanied by multiple changes in the endocrine and neuroendocrine axis which influences feed intake, somatotropic response, and hypothalamic-pituitary-adrenal axis hormone concentrations.