J. Anim Sci., doi: 10.2527/jas.2006-740
©Copyright, 2007, The American Society of Animal Science
Effects of weaning and weaning weight on neuroendocrine regulators of feed intake in pigs
C. J. Kojima 1*,
J. A. Carroll 2,
R. L. Matteri 2,
K. J. Touchette 3,
G. L. Allee 3
1 Department of Animal Science, University of Tennessee, Knoxville 37996
2 Animal Physiology Research Unit, ARS, USDA, Columbia 65211
3 Department of Animal Sciences, University of Missouri, Columbia 65211
* To whom correspondence should be addressed. E-mail: ckojima{at}utk.edu.
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Abstract |
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A depression in feed intake and growth often occurs in the weaned pig. Spray-dried plasma is often added to nursery diets in an attempt to stimulate feed intake during this lag. The present study evaluated gene expression of appetite regulators in hypothalamus and adipose tissue 4 d after weaning. Barrows (2 wk of age) were cross-fostered to a sow (SOW, n = 8) or weaned and fed a nursery diet containing either 0 or 7% spray-dried plasma (NP, n = 8, and SDP, n = 8; respectively). Piglets were allocated such that two size groups existed within each experimental group: small (3.5 to 4.3 kg piglets) and large (4.6 to 5.7 kg piglets). Animals were sacrificed 4 d after weaning for tissue collection. There was a weaning group by size interactive effect (P < 0.05) on hypothalamic neuropeptide Y mRNA expression such that expression was least in the small SDP piglets. No size or weaning group effects were seen on adipose leptin, hypothalamic leptin receptor or hypothalamic proopiomelanocortin gene expression. An effect of size was seen on hypothalamic neuropeptide Y agouti-related protein, orexin and type 2 orexin receptor gene expression such that large pigs expressed greater amounts of these transcripts (P < 0.002). Strong positive correlations in gene expression were found among all of these genes, whose products are known to stimulate appetite. Partial correlation controlling for initial BW revealed that pre-weaning size explained most if not all of these associations. These data suggest that the postweaning expression of appetite-regulating genes is more dependent on preweaning conditions than on weaning diet.
Key Words:
Appetite, growth, neuroendocrine, piglets, weaning
