Select for within-litter piglet birth weight uniformity to reduce mortality
Take Home Message: The variability in piglet birthweight can be reduced by breeding along with other factors such as avoiding very large litters and high backfat gain during pregnancy
Selecting for within-litter piglet birth weight uniformity would be a relevant approach to improve piglet survival. So says France’s INRA’s Hélène Quesnel.
“Within-litter variation of piglet birth weight (BW0) is associated with increased piglet mortality and a high variability in pig weight at weaning and weight or age at slaughter,” she explained.
“To investigate this, data collected in two experimental herds were used to quantify within-litter variability in BW0 and to assess the influence of factors mainly related to the sow.”
Within 24 hour of birth, piglets born alive were individually weighed and stillborn piglets were collectively (first data set) or individually (second data set) weighed. The first data set was restricted to litters with no or only one stillborn piglet (3,338 litters).
It was used to assess the influence of genetic selection on BW0 variation by comparing litter characteristics before (1994 to 1996) and after (2001 to 2004) the development of hyperprolific sows.
The second data set included all litters from sows born between 2000 and 2004. For each litter, mean BW0 and its coefficient of variation (a measure of the variability of birth weight, with higher figures indicating more variation) were calculated. Then, variance analyses were performed to test the influence of litter size, parity, year of sow birth and season at conception.
Prolificacy improvement was associated with an increased coefficient of variation in litters from pure Large White and crossbred sows. The coefficient averaged 21% and was significantly influenced by litter size and parity. It increased from 15% to 24% when litter size varied from less than 10 piglets to more than 15 piglets.
The coefficient of variation was not repeatable from one parity to the following, but it was lowest for first and second parities (20%) and thereafter increased progressively. The coefficient was positively related to sow’s backfat thickness gain during gestation.
“Litter size, parity, year of sow birth and season at conception explained 20% of BW0 variation. So a major part of heterogeneity is due to other factors, presumably including embryo genotype, and factors that influence embryo and foetus development, such as epigenetic factors,” added Dr Quesnel.
Full details: Quesnel H, Brossard L, Valancogne A and Quiniou N: “Influence of some sow characteristics on within-litter variation of piglet birth weight.” Animal 2: 1842-1849.
www.bsas.org.uk
For further information contact: BSAS on 0131 445 4508
