Evaluation of serum insulin-like growth factor binding proteins (IGFBP) in Angus cattle divergently selected for serum IGF-I concentration.
Postweaning serum insulin-like growth factor-I (IGF-I) concentrations and serum IGF binding proteins (IGFBP) were investigated in 68 (1992 Fall-born) and 84 (1999 Fall-born) Angus cattle selected for either high or low serum IGF-I concentrations since 1989. Relative serum levels of IGFBP were determined by [125I]IGF-I Western ligand blotting. IGFBP species of 38-42, 34, 30, and 24 kDa were identified. The 34 kDa species was identified as IGFBP-2 by immunoblot analysis. No significant line effects were observed for any of the IGFBP. In both 1992 and 1999, heifers had higher IGFBP-2 levels than bulls (P<0.0005). In 1992 calves, relative levels of the 38-42 and 24 kDa species were significantly correlated with serum IGF-I concentration. In 1999 calves, none of the IGFBP were correlated with serum IGF-I, although IGFBP-2 was negatively correlated with several measures of body weight. No significant line effects were observed for growth or serum IGF-I traits in 1992 calves. However, 1999 high line calves had higher serum IGF-I concentrations and body weights than low line calves (P<0.05). In both 1992 and 1999 calves, bulls had higher serum IGF-I concentrations and body weights than heifers (P<0.05). Thus, while selection for high versus low serum IGF-I concentrations has resulted in divergence between the selection lines and also in changes in body weights, it has not resulted in changes in serum IGFBP levels. Furthermore, circulating IGFBP-2 appears to be higher in heifers than in bulls, and also appears to be negatively correlated with body weights.
Pagan
M
M
Department of Animal Science, Michigan State University, 1205 Anthony Hall, East Lansing, MI 48824, USA.
Davis
M E
ME
Stick
D A
DA
Simmen
R C M
RC
Raney
N E
NE
Tempelman
R J
RJ
Ernst
C W
CW
D000818:Animals; D001699:Biometry; D015153:Blotting, Western; D001835:Body Weight; D002417:Cattle / Q000033:anatomy & histology / Q000097:blood / Q000235:genetics*; D005260:Female; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000097:blood; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007457:Iodine Radioisotopes; D008297:Male; D012641:Selection, Genetic; D012727:Sex Characteristics; D014886:Weaning; D015430:Weight Gain
D018971:Insulin-Like Growth Factor Binding Protein 2; D018969:Insulin-Like Growth Factor Binding Proteins; D007457:Iodine Radioisotopes; D007334:Insulin-Like Growth Factor I