Feeding of pregnant sows with mycotoxin-contaminated diets and their non-effect on foetal and maternal hepatic transcription of genes of the insulin-like growth factor system.

The insulin-like growth factor (IGF) system regulates foetal and placental growth. It can be influenced by dietary factors, but little is known about the effects of mycotoxin feeding on hepatic levels of the IGF system. The aim was (1) to determine the normal foetal and maternal hepatic transcription of major IGF genes at distinct stages of pregnancy and (2) to find out if the mycotoxins deoxynivalenol (DON) and zearalenone (ZON) affect transcript concentrations. Pregnant sows were fed with naturally contaminated diets from days 35 to 70 (experiment 1), or from days 75 to 110 (experiment 2), or with control diets. Foetal hepatic IGF transcripts were determined at days 70 and 110, maternal transcripts at day 70 by quantitative polymerase chain reaction (qPCR). The highest levels of IGF-I transcripts were found in sows. On the contrary, IGF-II was predominantly expressed in foetuses at day 70. Expression of IGF-IR and IGFBP-3 decreased, whereas that of IGFBP-2 increased towards term. IGF-IIR and IGFBP-1 expression was similar in both foetuses and full-term piglets. IGF-IIR showed reduced levels in the maternal liver. The exposure of pregnant sows to DON- and ZON-contaminated diets significantly reduced the maternal and tended to reduce the weight gain of piglets in experiment 2, but had no effects on hepatic levels of IGF transcripts in both experiments. This suggests that mycotoxin-contaminated diets can induce growth depression in pigs during pregnancy without affecting hepatic transcription of major IGF genes.