Article

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

ABSTRACT

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. "

    Full-text · Article · Feb 2015 · Livestock Science
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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. "
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    ABSTRACT: Records from 99,384 crossbred pigs from Duroc sires and Large White x Landrace dams were used to estimate genetic parameters for survival traits at different stages of the fattening period, and their relations with final weight. Traits analyzed were preweaning mortality (PWM), culling between weaning and harvesting (Call), culling during the farrowing period (Cfar), in the nursery site (Cnur), during the finishing phase (Cfin), and hot carcass weight (HCW). Because of the binary nature of PWM and culling traits, threshold-linear models were used: Model 1, including PWM, Call, and HCW; Model 2, including PWM, Cfar, Cnur, Cfin, and HCW. Both models included sex and parity number as fixed effects for all traits. Contemporary groups were considered as fixed effect for HCW and as random effects for the binary traits. Random effects were sire additive genetic, common litter, and residual effects for all traits and models. Heritability estimates were 0.03 for PWM, and 0.15 for HCW with both models, 0.06 for Call with Model 1, and 0.06 for Cfar, 0.14 for Cnur, and 0.10 for Cfin with Model 2. Litter variance explained a large part of the total variance and its influence declined slightly with age. For Model 1, genetic correlations were −0.36 between PWM and Call, −0.02 between PWM and HCW, and −0.25 between Call and HCW; correlations for litter effect were -0.15 between PWM and Call, −0.19 between PWM and HCW, and −0.21 between Call and HCW. For Model 2, genetic correlations were all positive between PWM and culling traits, except between PWM and Cnur (−0.61). Genetic correlations between HCW and the other traits were moderate and negative to null. Correlations for common litter effect were all negative between traits, except between Cfar and Cfin, and between Cnur and Cfin. Heritability of PWM and culling traits increased with age period. Therefore, selection for survival after weaning may be more efficient. The low genetic correlations between PWM and culling traits suggest that different genes influence pre- and postweaning mortality. The HCW was not correlated with the other traits. However, relationships are not strongly unfavorable, therefore selection for survival and high final weight is possible.
    Full-text · Article · Sep 2014 · Livestock Science
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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.
    Full-text · Article · Mar 2013 · Journal of Animal Science
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