Genetic analyses of piglet survival and individual birth weight on first generation data of a selection experiment for piglet survival under outdoor conditions

Abstract

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

Genetic parameters for piglet survival, litter size and birth weight or its variation within litter in sire and dam lines using Bayesian analysis

“…The influence of adjustment for litter size differed between papers (e.g. Roehe, 1999;Roehe et al, 2009) and might be dependent on the population analysed. The unfavourable correlations between the direct and maternal genetic effect of survival suggest that selection on either component might compromise overall improvement if no simultaneous selection on the other genetic effect occurs.…”

“…The much greater magnitudes of the maternal genetic effect compared to the direct genetic effect indicate that SVBP depends more on the genetic effect of the dam rather than the piglet. Studies that considered both genetic effects found heritabilities for the direct genetic effect of survival at birth ranging from 0.00 to 0.10 and for the maternal genetic effect ranging from 0.03 to 0.13 in various breeds (Knol et al, 2002;Su et al, 2008;Ibáñez-Escriche et al, 2009;Roehe et al, 2009).…”

“…Recently, extensive research has been carried out to examine the potential to increase piglet survival by genetic improvement. Heritabilities of traits related to piglet survival have been estimated, and even though they are generally low, the genetic variation is large enough to provide improvement through breeding (Knol et al, 2002;Su et al, 2008;Roehe et al, 2009). Breeding goal differences, with emphasis on reproduction traits within dam lines and on production traits within sire lines, may result in different genetic parameters between lines (Knol et al, 2002;Kapell et al, 2009).…”

“…This allows the threshold characteristic of individual piglet survival at birth to be taken into account, and provides an opportunity to examine the precision of estimation of genetic parameters by using Bayesian confidence intervals. Additionally, birth weight and survival at birth have often only been analysed at the litter level, as a trait of the dam, while few studies took the genetic component of the individual piglet into account (Grandinson et al, 2002;Su et al, 2008;Roehe et al, 2009). However, individual piglet birth weight may be closely related to piglet survival and might therefore be used to indirectly improve piglet survival at birth.…”

Heritabilities of agonistic behavioural traits in pigs and their relationships within and between different age groups

“…The litter effect included both maternal genetic and maternal environmental effects . For pigs, the litter effect is usually known as a random effect in models describing traits such as feed conversion, weight gain or piglet survival (Johnson et al, 1999;Kuhlers et al, 2003;Roehe et al, 2009). For rodents, previous findings have shown that the offspring's behavioural performance is influenced by the mother's behaviour.…”