Variance and covariance components for liability of piglet survival during different periods

Abstract

Variance and covariance components for piglet survival in different periods were estimated from individual records of 133 004 Danish Landrace piglets and 89 928 Danish Yorkshire piglets, using a liability threshold model including both direct and maternal additive genetic effects. At the individual piglet level, the estimates of direct heritability in Landrace were 0.035, 0.057 and 0.027, and in Yorkshire the estimates were 0.012, 0.030 and 0.025 for liability of survival at farrowing (SVB), from birth to day 5 (SV5) and from day 6 to weaning (SVW), respectively. The estimates of maternal heritability for SVB, SV5 and SVW were, respectively, 0.057, 0.040 and 0.030 in Landrace, and 0.050, 0.038 and 0.019 in Yorkshire. Both direct and maternal genetic correlations between the three survival traits were low and not significantly different from zero, except for a moderate direct genetic correlation between SVB and SV5 and between SV5 and SVW in Landrace. Direct and maternal genetic correlations between piglet birth weight (BW) and SV5 were moderately high, but the correlations between BW and SVB and between BW and SVW were low and most of them were not significantly different from zero. These results suggest that effective genetic improvement in piglet survival before weaning by selection should be based on both direct and maternal additive genetic effects and treat survival in different periods as different traits.

Estimation of genetic associations between reproduction and production traits based on a sire and dam line with common ancestry

“…Few studies have differentiated between a sire and dam line, and none of them originating from the same breed . Studies analysing and comparing different breeds showed that there are clear differences in genetic parameters between breeds (See et al, 1993;Roehe and Kennedy, 1995;Su et al, 2008). Only a few studies (Ferraz and Johnson, 1993;Hermesch et al, 2000c;Serenius et al, 2004b) have used data from Large White pigs in their studies to compare different breeds, and none of these studies differentiated between sire and dam line within the breed.…”

“…Generally estimates for the maternal genetic effects in these studies are higher than the direct genetic effect (Grandinson et al, 2005;Rydhmer et al, 2008;Su et al, 2008). In this study, survival as SB was analysed at sow level, since individual piglet information was not available.…”

“…Several studies over the years looked at the survivability of piglets at birth and from birth till weaning and research has been carried out to determine the heritabilities of traits related to piglet survival (e.g. Rydhmer et al, 2008;Su et al, 2008). These heritabilities are generally low, but the genetic variation is large enough to provide improvement through breeding.…”

Genetic architecture of rainbow trout survival from egg to adult

“…Campbell (1997) found low and non-significant genetic correlation between seedling emergence and survival to flowering in a monocarpic herb Scarlet Gilia (Ipomopsis aggregata). Studies on piglet mortality from farrowing to weaning around 4 weeks of age have found close to zero or even negative genetic correlations between different periods, thus suggesting that different piglet survival traits do not share a common genetic background and should be treated as separate traits (Su et al, 2008, and references therein). Ducrocq et al (2000) found that survival of laying hens during rearing (from birth to housing at 106 days) and productive periods (from housing to 313 days of age) are genetically different traits with different mortality rates and genetic correlation close to zero.…”

“…Low heritability of survival has been found in diverse taxonomic groups in farmed terrestrial animals (e.g. van Arendonk et al, 1996;Ducrocq et al, 2000 ;Knol et al, 2002;Goyache et al, 2003 ;Casellas et al, 2007 ;Su et al, 2008) and in wild organisms (e.g. Futuyma et al, 1995;Campbell, 1997).…”