Recent estimates of total pre-weaning piglet mortality range between 16-19% (MLC 2006). With environmental modification using the farrowing crate reaching its potential to decrease mortality, as well as raising serious welfare concerns, a different approach to effectively address piglet survival is needed. Genetic breeding programmes implemented in alternative farrowing systems could prove a viable option.

Piglet survival is based on a complex interaction between the piglets own genetic component (direct genetic effects), the dams genetic contribution (maternal genetic effects) and environmental effects (systematic environmental such as year-season, common litter and individual environmental effects). Disentanglement of direct and maternal genetic effects needs a powerful design of genetic relationships. In order to accomplish this, a two generation selection experiment was designed with different selection groups for direct and maternal effects and cross-classification of these selection groups. Survival at birth and survival during the nursing period may have genetically independent components and would then be treated as different traits. In addition, piglet survival traits are reported to have low direct and maternal heritabilities and traits genetically associated with survival, such as birth weight, may result in a more efficient change in survival than using survival per se. Therefore, the objective of the research was to estimate the genetic parameters of direct and maternal genetic effects of survival and birth weight in order to enhance the selection strategies for piglet survival.

Peri- and postnatal mortality of piglets is reported to be around 20% and genetic improvement in piglet survival has great potential benefits in terms of animal welfare, economics and the environment. The indication of an unfavourable genetic correlation between litter size and survival in particular points to the importance of including piglet survival in those pig breeding programmes that currently only aim to increase litter size. Phenotypically, individual birth weight is closely associated with piglet survival (Roehe and Kalm, 2000). Genetic parameters for piglet survival traits and individual birth weight therefore need to be estimated in order to genetically improve piglet survival efficiency