Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/1997
Publication Date: N/A
Technical Abstract: Age-dependent interactions between environmental temperature and pGH treatment on the function of the somatotrophic axis were evaluated in the neonatal pig. At 3 d of age, 40 Landrace X Yorkshire X Duroc piglets received intraperitoneal implants containing either recombinant pGH (.5 mg/day; n=20) or saline (Control; n=20). Piglets were maintained with the sows at either a low (20 deg C, 50% RH; n=20) or high (32 deg C, 50% RH; n=20) temperature. At 4 wk and 6 wk of age, 1/2 of the piglets from each group were sacrificed for blood and tissue collection. Serum concentra- tions of GH, IGF-1, and IGF-2 were determined. Liver GH receptor (GH rec), IGF-1, IGF-2, and IGF binding protein 3 (IGFBP-3) mRNAs were quantified. There was no effect of pGH (P>0.10) on ADG; however, there was an effect of both age (P<0.002) and temperature (P<0.003) on ADG such that those animals maintained at a low temperature and those sacrificed at 6 wk of age had greater ADGs. Serum concentration of GH was elevated by pGH (P<0.004), an was greater in the 4-wk age groups (P<0.02). Serum concentration of IGF-1 was enhanced by pGH (P<0.007) and increased with age (P<0.01). Serum concentration of IGF-2 tended to be elevated by pGH (P<0.08). Liver GH rec mRNA was unaffected by pGH (P>0.10), but was greater in the 6-wk age groups (P<0.0001) and in piglets maintained at the high temperature (P<0.04). IGF-1 mRNA was enhanced by pGH (P<0.0003) and by exposure to high temperature (P<0.03), but did not differ between age groups (P>0.10). IGF- 2 mRNA was greater in the 4-wk age groups (P<0.002) and in piglets maintained at the high temperature, but was unaffected by pGH (P>0.10). IGFBP-3 mRNA was elevated by pGH (P<0.04) and increased with age (P<0.0008).