Influence of Nutritional Factors on Placental Growth and Piglet Imprinting

Uterine crowding affects pre- and post-natal development in pigs. Uterine crowding is a consequence of the selection on litter size resulting in high ovulation rates with increasing pressure on embryonic and foetal development and survival. Placental development is decreasing with increasing numbers of foetuses in the uterus and has negative consequences on foetal development. The consequences of placental insufficiency are considerable according to the theory of ‘foetal origins of adult disease’ or the ‘Barker theory’. Placental insufficiency in rats results in post-natal DNA hypo-methylation, indicating the negative effects on methylation processes and is expected to be the cause for permanent modifications in the chromatin structure (imprinting). In pigs it has been shown that crowding affects pre- and post-natal muscle development (number of secondary fibres, important for post-natal growth). The negative effects of crowding on placental development and consequently foetal development in pigs might be compensated by specific nutrients. Factors affecting methylation processes like Folic acid, B-vitamins and related compounds are therefore of specific interest. Recently it has also been shown that addition of L-Arginine in the diet affects placental development, improves embryonic survival and results in increased litter size. This workshop will focus on these aspects affecting prenatal development and survival.