Hyper-Prolificacy and Acceptable Post-Natal Development - A Possible Contradiction

Although the components of litter size (ovulation rate, embryonic survival and uterine capacity) responsive to genetic selection are well established. However, the reality in existing “hyper-prolific” sows is that increased selection pressure for numbers born has led to indirect negative effects of intra-uterine crowding, reprogramming of fetal development, less efficient post-natal growth performance and adverse effects on carcass quality at slaughter. Therefore, a considerable amount of the variation in growth performance after birth may be pre-programmed during fetal development in the uterus (see Foxcroft and Town, 2004). The effects of prenatal programming on postnatal performance are not limited to effects on muscle development and growth. Harding et al. (2006) showed that the organs most notably affected by pre-natal programming in stillborn pigs with low birth weight were the heart, liver and spleen, with obvious implications for post-natal health outcomes generally.