Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/1999
Publication Date: N/A
Technical Abstract: One of the greatest challenges in swine nutrition is to decrease the postweaning lag by stimulating feed intake and growth. Spray-dried plasma (SDP) is often added to phase 1 diets to attempt to stimulate appetite during this lag. The current study was designed to investigate changes in gene expression (messenger ribonucleic acid, mRNA) of neuroendocrine appetite regulators during weaning. Young pigs (14d, 4.69+/0.13 kg) were either crossfostered to a sow (SOW, n=8), weaned and fed a phase 1 diet containing no SDP (NP, n=8), or weaned and fed a diet containing 7% SDP (SDP, n=8). Animals were sacrificed 4d after weaning (or crossfostering) for tissue collection. Gene expression was compared between treatments using initial (pre-weaning) body weight as a covariate. Expression of neuropeptide Y (NPY), a potent stimulator of feed intake, was equivalently decreased (P=0.011) in SDP and NP pigs compared to SOW pigs. There were no otreatment effects seen on adipose leptin, or hypothalamic leptin receptor, orexin (ORX), orexin receptor type 2 (Orec2), or insulin-like growth factor 1 (IGF-I) gene expression. Correlation analysis revealed significant (P<0.001) correlations between initial body weight and hypothalamic ORX, Orec2, NPY, and IGF-1 expression (R=0.664,0.759, 0.791, and 0.697, respectively) across treatments. Interestingly, no such pattern was observed for adipose leptin or hypothalamic leptin receptor expression. Expression of Orec2 mRNA was strongly correlated to ORX expression across treatments (R=0.690, P=0.0002). This study provides not only the first report of endogenous orexin mRNA expression in a livestock species, but gives new insight into the neurochemical impact of weaning.