Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 1997
Publication Date: N/A
Technical Abstract: The objective of this study was to determine the effects of weaning and changing post-weaning diet composition on growth patterns and growth- related hormonal profiles in neonatal pigs. Forty-eight crossbred piglets were assigned to two groups (n=24/group) based on weaning at 2 or 3 wk of age. At the specified weaning time for each group, piglets were removed from the sow and placed on a commercial starter ration for the first 11 d post-weaning (Phase I diet). At d 12 post-weaning, the piglets were placed on a growing ration for the remainder of the study (Phase II diet). Body weights and blood samples were collected twice weekly from birth until 42 d of age. Serum hormone concentrations (GH, IGF-1, IGF-2, T3, T4 and cortisol) were determined by RIA. Serum concentrations of IGF-1, IGF-2, and ADG were reduced (P<.05) in both groups as a result of weaning, whereas serum concentrations of GH were elevated (P<.05) in both groups. Mild decreases in ADG occurred following the change from phase I to phase II diets (P<.05). Serum IGF-1 concentrations decreased following the phase I to II dietary change in the 2 wk weaning group (P<.05). The numerical increases in GH secretion following the change in diets were not significant in either group (P<.05). A developmental decline in serum T3 concentrations occurred from birth to d 18 in both experimental groups (P<.05). Serum T3 levels were not affected by weaning at either 2 or 3 wk of age, but did decline in both groups following the change in post-weaning diets (P<.05). Change in the patterns of T4 and cortisol secretion was not associated with weaning or the change in diets. These results demonstrate that growth-related endocrine function is affected by management practices associated with dietary changes in the neonatal pig.