Effect of chronic undernutrition on growth, serum insulin-like growth factor-I (IGF-I) and insulin-like growth factor-binding proteins (IGFBP) in pigs

The present study aims to look at the long-term effects of undernutrition ( both quantitative and qualitative) on growth, serum IGF-I and IGFBP pattern in growing pigs. 144 (Large White X Landrace) male pigs were randomly divi ded into three groups, after weaning. Group 1 was fed on diets containing r aw soya beans (R), group 2 was fed on heat-treated soya ad libitum (C) and group 3 was on heat-treated soya, but 50% restricted feeding (CR). The feed ing trial lasted for 6 months. Sera were collected every month for IGF-I an d IGFBP assays. Average daily gain was lower (p<0.01) in the CR group. Thre e phases of growth pattern were recognised and they were almost similar in the C & R group, but distinctly different in the CR group. The serum IGF-I levels in the C & R groups were lower at 8 months (p<0.05) compared to leve ls at 2 months. However, in the CR group the serum IGF-I levels were higher at 7 (p<0.05) and 8 months (p<0.001) compared to levels at 2 months. The w estern ligand blots showed five IGFBP bands, ranging from 43000 to 18000 mo lecular mass (M-r). The IGFBP-1 and 2 band intensity appeared to increase w ith age, although declining at 8 months in C group. In R and CR groups, the IGFBP 1 and 2 band intensities were similar at X months irrespective of th e changes in IGF-I concentration. It is suggested that the growth inhibitio n in CR group may be attributed to altered developmental pattern of serum I GF-I concentration, due to uncoupling of GH/IGF-I axis. (C) 2000 Elsevier S cience Inc.