Genetic parameters of piglet survival and birth weight from a two-generation crossbreeding experiment under outdoor conditions designed to disentangle direct and maternal effects

Sustainable Livestock Systems Group, Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG, United Kingdom.
Journal of Animal Science (Impact Factor: 2.11). 12/2009; 88(4):1276-85. DOI: 10.2527/jas.2009-2287
Source: PubMed


Multivariate Bayesian linear-threshold models were used to estimate genetic parameters of peri- and postnatal piglet survival and individual birth weight of piglets reared under outdoor conditions. Data of 21,835 individual piglet observations were available from a 2-generation crossbreeding experiment selected for direct and maternal genetic effects of postnatal piglet survival on piglet and dam levels, respectively. In the first generation, approximately one-half of the Landrace sires used were selected for large or average breeding values of maternal genetic effects on postnatal piglet survival, whereas in the second generation the Large White sires used were selected for direct genetic effects of the same trait. Estimates of direct and maternal heritability were 0.21 and 0.15, 0.24 and 0.14, and 0.36 and 0.28 for piglet survival at birth and during the nursing period, and individual birth weight, respectively. In particular, direct heritabilities are substantially larger than those from the literature estimated for indoor-reared piglets, suggesting that genetic effects of these traits are substantially greater under outdoor conditions. Direct or maternal genetic correlations between survival traits or with birth weight were small (ranging from 0.06 to 0.17), indicating that peri- and postnatal survival are genetically under rather different control, and survival was only slightly positively influenced by birth weight. There were significant (P < 0.05) negative genetic correlations between direct and maternal genetic effects within each of the analyzed traits ranging from -0.36 to -0.45, which have to be considered when selecting for piglet survival. Adjustment of traits for litter size or inclusion of genetic groups showed insignificant effects on the magnitude of the estimated genetic parameters. The magnitude of genetic parameters suggested that there is substantial potential for genetic improvement of survival traits and birth weight in direct and maternal genetic effects, especially when piglets are kept under outdoor conditions.

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Available from: Rainer Roehe, Sep 16, 2015
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    • "In the literature, the proportion of total variance explained by litter at market age was 4–6% for backfat and 5–12% for weight per day of age and HCW (Lutaaya et al., 2001; Zumbach et al., 2007). However, the common litter effects found in this study were higher than those reported for similar traits in other studies (Zumbach et al., 2007; Roehe et al., 2010), also probably because maternal effect was part of litter effect. Table 4 Estimates (SE) of heritability, sire genetic, and litter effects for survival traits by the statistical model. "
    Livestock Science 02/2015; 174. DOI:10.1016/j.livsci.2015.02.002 · 1.17 Impact Factor
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    • "Consequently, selection for increasing TNB will increase the number of stillborn as well as the preweaning mortality. Previous studies have showed that there is a substantial potential for genetic improvement of piglet survival, especially when piglet mortality is high as under outdoor production systems (Roehe et al., 2010). It was observed that most cases of death occurred at farrowing and during the first 5 d after farrowing in Danish Landrace and Yorkshire (Su et al., 2007, 2008). "
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    ABSTRACT: Selection for litter size at day five after farrowing (LS5) was introduced in 2004 in order to increase number of piglets weaned and reduce piglet mortality in Danish Landrace and Yorkshire. The objective of this study was to investigate selection responses for LS5, total number born (TNB) and mortality (MORT, defined as (TNB-LS5)/TNB), when selection for increasing LS5 was a part of the breeding goal. Data were collected from nucleus herds recorded from 2004 to 2010, including first litters of 42,807 Landrace sows and 33,225 Yorkshire sows. The data were analyzed using a three-trait animal model of TNB, MORT and LS5. Significant (co)variances were estimated between the three traits in both populations. The heritabilities of TNB, MORT, and LS5 were 0.10, 0.09, and 0.09 in Landrace and 0.12, 0.10, and 0.10 in Yorkshire. The genetic correlations were 0.28 and 0.22 between TNB and MORT, 0.74 and 0.68 between TNB and LS5, and -0.43 and -0.57 between MORT and LS5 in Landrace and Yorkshire, respectively. The results show that the genetic improvement of LS5 was a combination of increased TNB and reduced MORT. During the observation period, the genetic improvement was 1.7 piglets per litter for LS5, 1.3 piglets per litter for TNB and 4.7% for MORT in Landrace, and 2.2 piglets per litter, 1.9 piglets per litter, and 5.9% in Yorkshire. Phenotypic improvement was 1.4 piglets per litter for LS5, 0.3 piglets per litter for TNB, and 7.9% for MORT in Landrace, and 2.1 piglets per litter, 1.3 piglets per litter, and 7.6% in Yorkshire. In addition, genetic gain was evaluated in three phenotypic groups of TNB, representing the 25% smallest litters, the 50% medium litters, and the 25% largest litters. In all three groups, the genetic and phenotypic gains of TNB and LS5 increased while MORT reduced in both populations.
    Journal of Animal Science 03/2013; 91(6). DOI:10.2527/jas.2012-5990 · 2.11 Impact Factor
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    • "For instance, in farm animals, growth and survival are sometimes positively correlated (e.g. Chicken: de Greef et al. 2001; Lambs: Riggio et al. 2008; Pigs: Roehe et al. 2010). Accordingly, there is a need for increased understanding why genetic correlations between growth and fitness components are sometimes positive and sometimes negative and what causes the variation in the sign. "
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    ABSTRACT: Explanations for positive and negative genetic correlations between growth and fitness traits are essential for life-history theory and selective breeding. Here, we test whether growth and survival display genetic trade-off. Furthermore, we assess the potential of third-party traits to explain observed genetic associations. First, we estimated genetic correlations of growth and survival of rainbow trout. We then explored whether these associations are explained by genetic correlations with health, body composition and maturity traits. Analysis included 14 traits across life stages and environments. Data were recorded from 249 166 individuals belonging to 10 year classes of a pedigreed population. The results revealed that rapid growth during grow-out was genetically associated with enhanced survival (mean r(G) = 0.17). This resulted because genotypes with less nematode caused cataract grew faster and were more likely to survive. Fingerling survival was not genetically related to weight or to grow-out survival. Instead, rapid fingerling growth made fish prone to deformations (r(G) = 0.18). Evolutionary genetics provides a theoretical framework to study variation in genetic correlations. This study demonstrates that genetic correlation patterns of growth and survival can be explained by a set of key explanatory traits recorded at different life stages and that these traits can be simultaneously improved by selective breeding.
    Evolutionary Applications 11/2012; 5(7):732-45. DOI:10.1111/j.1752-4571.2012.00251.x · 3.90 Impact Factor
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