Ontogenetic development of the IGF-system and leptin in offspring of sows fed with gestation diets differing in protein content

The aim of this dissertation was to characterize leptin and the different components of the IGF-system in offspring of sows fed with different protein contents throughout pregnancy and to ascertain long term consequences caused by an inadequate nutritional environment in utero. German Landrace gilts (n=78) were fed gestation diets (~15.4 MJ ME/kg) of either low (LP, 6%; n=26), adequate (AP, 12%; n=26), or high (HP, 30%; n=24) protein content. For sampling at day 94 of gestation, 26 gilts with their fetuses were investigated. At parturition, the offspring of the remaining 52 gilts were cross fostered to nursing sows fed a standard lactation diet. Fetal and birth weight of all investigated offspring were recorded and classified into 2 different fetal body weight classes (Fbwc ¿ or > 0.65 kg) or birth weight classes (Bbwc ¿ or > 1.3 kg). In addition, the litter size of any gilt was classified into two groups (Lsgr ¿ or > 12 piglets). Blood and liver samples from 306 piglets in total were collected. In detail, fetuses of day 94 of gestation (dpc), and piglets at their 1st, 28th and 188th day of life (dpn) were sampled. Blood samples were assayed for IGF-1, IGF-2 and leptin by ELISA and for IGF binding proteins via a quantitative, non-radioactive Western ligand blotting protocol established and optimized herein. Liver samples were assayed for IGF-1 receptor by use of ELISA. The concentrations of leptin in offspring were not affected by maternal diet over all postnatal days. With the exception of dpn 1, the IGF-1 concentrations remained unchanged in response to maternal dietary treatment. Piglets born to mothers fed the LP diet had decreased IGF-1 concentrations compared to piglets born to HP mothers (P