Document Detail

Genetic analysis of litter size, parturition length, and birth assistance requirements in primiparous sows using a joint linear-threshold animal model.
MedLine Citation:
PMID:  15446467     Owner:  NLM     Status:  MEDLINE    
The aim of this study was to investigate whether selection for number of live born piglets has led to prolonged parturition and increased requirement for birth assistance, resulting in increased numbers of stillborn piglets. Data were collected from 6,718 primiparous Norwegian Landrace sows farrowing between 2001 and 2003. The need for birth assistance was recorded as a binary response. Physical intervention in the birth of piglets and/or hormonal treatment by the farmer was recorded as birth assistance. The duration of the parturition was analyzed as a binary trait (<4 h and >4 h). The statistical model used for analysis included contemporary groups of herd-year, litter breed, season of farrowing, parity in which the sow was born, a regression on the age of sow at farrowing, an additive genetic effect, and a service sire effect. A full Bayesian approach via Gibbs sampling was adopted to estimate the genetic relationships between these four traits. A total chain length of 100,000 iterations was run. The first 10,000 samples were discarded as burn-in, and the remaining 90,000 iterations were retained without thinning for post-Gibbs analysis. The highest direct heritability was estimated for the number of live-born piglets (h2 = 0.07), followed by the duration of farrowing (h2 = 0.05), the need for birth assistance (h2 = 0.05), and the number of stillborn piglets (h2 = 0.04). The genetic correlations revealed that the number of live and stillborn piglets was uncorrelated; however, the number of live piglets born had a moderate genetic correlation to the need for birth assistance (rg = 0.24 +/- 0.01) and duration of farrowing (rg = -0.20 +/- 0.01), whereas the number of stillborn piglets was highly correlated to the need for birth assistance (rg = 0.74 +/- 0.01) and the duration of parturition (rg = 0.66 +/- 0.01). The duration of farrowing and the need for birth assistance were genetically highly correlated (rg = 0.89 +/- 0.00). For all traits, the service sire variance was approximately one quarter in magnitude compared with its respective genetic variance. The results showed that selection for the number of live born piglets is not expected to influence the number of stillborn piglets. Increasing the number of live piglets born through selection should have a slight negative effect on farrowing duration and a minor increase in the need for birth assistance. Sows with a high genetic potential for birth assistance and prolonged parturition were more likely to give birth to greater numbers of stillborn piglets.
B Holm; M Bakken; O Vangen; R Rekaya
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of animal science     Volume:  82     ISSN:  0021-8812     ISO Abbreviation:  J. Anim. Sci.     Publication Date:  2004 Sep 
Date Detail:
Created Date:  2004-09-27     Completed Date:  2005-04-04     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  8003002     Medline TA:  J Anim Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2528-33     Citation Subset:  IM    
Norsvin, Hamar, Norway.
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MeSH Terms
Bayes Theorem
Dystocia / epidemiology,  genetics,  veterinary*
Fetal Death / epidemiology,  genetics,  veterinary
Linear Models
Litter Size / genetics*
Models, Genetic
Parturition / genetics*
Pregnancy Outcome / epidemiology,  genetics,  veterinary
Selection, Genetic*
Swine / genetics*
Time Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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