Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/1998
Publication Date: N/A
Technical Abstract: Our objective was to determine what effects the natural birth process would have on the development of the somatotrophic axis in the neonatal pig. Eight crossbred sows were selected for the study (n=4 each for natural birth and Caesarian-Section). Blood and tissue samples from 38 piglets were collected at birth to establish baseline values. Remaining piglets were sustained with the natural birth sows until 2 wk of age at which time 39 piglets were sacrificed for blood and tissue samples. Gestational age at birth did not differ (P>.16) between the natural birth and C-Section piglets (113.6 +/ .14 and 113.2 +/ .27 days, respectively). Serum growth hormone (GH) did not differ (P>.86) between the two groups at birth, but was greater (P<.038) at 2 wk in the C-Section piglets as compared to the natural birth piglets (19.46 +/ 2.63 and 12.44 +/ 1.99 ng/ml, respectively). Serum insulin-like growth factor 1 (IGF-1) was greater (P<.003) in the natural birth piglets as compared to the C-Section piglets (28.77 +/ 2.08 and 20.87 +/ 1.4 ng/ml, respectively) at birth but did not differ at 2 wk of age. Pituitary GH mRNA and GH-releasing hormone receptor mRNA did not differ (P>.14) between the two groups; however, expression of both mRNAs declined (P<.0002) from birth until 2 wk of age. Liver expression of IGF-1 mRNA did not differ (P>.80) between natural birth and C-Section; however, there was an increase (P<.0001) in both groups from birth to 2 wk of age. Liver expression of GH receptor mRNA was greater in the C-Section piglets as compared to the natural birth piglets at birth (P<.038) and at 2 wk of age (P=.006). These data support our hypothesis that the natural birth process may significantly alter the post-natal function of the somatotrophic axis in the neonatal pig.