Genetic variation and responses in reproductive performance of sows in lines selected for growth rate under restricted feeding

Abstract

The objective of this study was to examine genetic changes in reproduction traits in sows (total number born (TNB), number born alive (NBA), average piglet birth weight (ABW) and number of piglets weaned (NW), body weight prior to mating (MW), gestation length (GL) and daily food intake during lactation (DFI)) in lines of Large White pigs divergently selected over 4 years for high and low post-weaning growth rate on a restricted ration. Heritabilities and repeatabilities of the reproduction traits were also determined. The analyses were carried out on 913 litter records using average information-restricted maximum likelihood method applied to single trait animal models. Estimates of heritability for most traits were small, except for ABW (0·33) and MW (0·35). Estimates of repeatability were slightly higher than those of heritability for TNB, NBA and NW, but they were almost identical for ABW, MW, GL and DFI. After 4 years of selection, the high growth line sows had significantly heavier body weight prior to mating and produced significantly more piglets born alive with heavier average birth weight than the low line sows. There were, however, no statistical differences between the selected lines in TNB or NW. The lower food intake of high relative to low line sows during lactation was not significant, indicating that daily food intake differences found between grower pigs in the high and low lines (2·71 v. 2·76 kg/day, s.e.d. 0·024) on ad libitum feeding were not fully expressed in lactating sows. It is concluded that selection for growth rate on the restricted ration resulted in beneficial effects on important measures of reproductive performance of the sows.

Empirical Bayes factor analyses of quantitative trait loci for gestation length in Iberian × Meishan F2 sows

“…Within this context, we must be cautious with the heritability provided by the current analysis (h 2 50.13). This moderate value contrasts with the high heritabilities reported by Hanenberg et al (2001) and Cassady et al (2002), although it is similar to the one described by Nguyen et al (2006).…”

“…The moderate to high values of heritability estimated for gestation length during last decade (Hanenberg et al, 2001;Serenius et al, 2004;Nguyen et al, 2006) have increased its importance as a potential breeding goal to improve the efficiency of the sow per time unit. On the other hand, an increase in gestation length has been related with an improved piglet vitality at birth and the reduced stillbirths (Zaleski and Hacker, 1993;Leenhouwers et al, 1999;Knol et al, 2002).…”

Influence of some sow characteristics on within-litter variation of piglet birth weight

“…Repeatability of mean BW0 and within-litter BW0 variation Estimates of repeatability for litter size were similar to those previously reported (Le Cozler et al, 1997;Damgaard et al, 2003;Nguyen et al, 2006). Values of repeatability for CV BW0 were similar in both herds.…”

“…in birth weight. Repeatability for mean BW0 was much stronger, as previously described (Damgaard et al, 2003;Nguyen et al, 2006). Repeatability for maximal BW0 was also found to be strong, whereas repeatability for minimal BW0 was low.…”

A whole genome scan to detect quantitative trait loci for gestation length and sow maternal ability related traits in a White Duroc × Erhualian F2 resource population

“…The moderate-to-high heritability estimates for gestation length (Hanenberg et al, 2001;Nguyen et al, 2006) have increased the potential of this trait as a breeding goal to improve the sow reproduction efficiency. Three QTL were detected for gestation length in this study and the QTL on SSC2 and SSC12 were detected for the first time.…”