Submitted to: Journal of Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2003
Publication Date: 6/4/2003
Citation: SALFEN, B.E., CARROLL, J.A., KEISLER, D.H. ENDOCRINE RESPONSES TO SHORT-TERM FEED DEPRIVATION IN WEANLING PIGS. JOURNAL OF ENDOCRINOLOGY. 2003. V. 178. P. 541-551. Interpretive Summary: Low feed intake by pigs during weaning leads to a suppression of weight gain and may also increase susceptibility to diseases. Our objective was to characterize the hormonal changes that take place during a feed-deprivation period similar to that commonly observed during weaning in pigs. The study elucidated the endocrine control of feed intake in pigs and may prove useful in developing methods to increase feed intake in pigs during weaning, when feed intake is typically low. If a method of increasing feed intake in pigs can be developed, the health and growth of the pig will be increased. This will result in pigs that reach market weight faster, thus saving the producer money associated with feed, medication and facility costs. The end result will be an increased efficiency of pork production. This data will be of interest to all individuals associated with swine production including scientists in academia, government, and industry.
Technical Abstract: Low feed intake by pigs during weaning leads to a suppression of weight gain and may also increase susceptibility to diseases. Our objective was to characterize the hormonal changes that take place during a feed-deprivation period similar to that commonly observed during weaning in pigs. In Experiment 1, eight barrows 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 to CON pigs, but greater than CON pigs at 24 and 30 h (P < 0.01). Serum IGF-I was lower in FD pigs from 12 to 30 h as compared to CON pigs (P < 0.05) and increased following re-feeding (P < 0.06). Experiment 2 included of 32 pigs that were either fed (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), but greater at 36 h and 48 h than CON pigs (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 re-feeding (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 to CON pigs. These results provide evidence that feed deprivation is accompanied by multiple changes in the endocrine and neuroendocrine axis which influences feed intake, somatotrophic response, and HPA axis hormone concentrations.