Genetic Parameters for Litter Size in Pigs Using a Random Regression Model

  • Lukovic, Z. (Faculty of Agriculture, University of Zagreb) ;
  • Uremovic, M. (Faculty of Agriculture, University of Zagreb) ;
  • Konjacic, M. (Faculty of Agriculture, University of Zagreb) ;
  • Uremovic, Z. (Faculty of Agriculture, University of Zagreb) ;
  • Vincek, D. (Croatian Livestock Center)
  • Received : 2006.03.10
  • Accepted : 2006.07.10
  • Published : 2007.02.01


Dispersion parameters for the number of piglets born alive were estimated using a repeatability and random regression model. Six sow breeds/lines were included in the analysis: Swedish Landrace, Large White and both crossbred lines between them, German Landrace and their cross with Large White. Fixed part of the model included sow genotype, mating season as month-year interaction, parity and weaning to conception interval as class effects. The age at farrowing was modelled as a quadratic regression nested within parity. The previous lactation length was fitted as a linear regression. Random regressions for parity on Legendre polynomials were included for direct additive genetic, permanent environmental, and common litter environmental effects. Orthogonal Legendre polynomials from the linear to the cubic power were fitted. In the repeatability model estimate of heritability was 0.07, permanent environmental effect as ratio was 0.04, and common litter environmental effect as ratio was 0.01. Estimates of genetic parameters with the random regression model were generally higher than in the repeatability model, except for the common litter environmental effect. Estimates of heritability ranged from 0.06 to 0.10. Permanent environmental effect as a ratio increased along a trajectory from 0.03 to 0.11. Magnitudes of common litter effect were small (around 0.01). The eigenvalues of covariance functions showed that between 7 and 8 % of genetic variability was explained by individual genetic curves of sows. This proportion was mainly covered by linear and quadratic coefficients. Results suggest that the random regression model could be used for genetic analysis of litter size.


Pigs;Litter Size;Random Regression Model;Genetic Parameters


  1. Chu, M. X. 2005. Statistical analysis of stillbirths in different genotypes of sows. Asian-Aust. J. Anim. Sci. 18:1475-1478.
  2. Kovac, M., E. Groeneveld and L. A. Garcia-Cortes. 2002. VCE-5, a package for the estimation of dispersion parameters. In Proceedings of the 7th World Congress on Genetics Applied to Livestock Production, Montpelier, France, 33:741-742.
  3. SAS Institute Inc. 2001. The SAS System for Windows, Release 8.02. SAS Institute Inc., Cary, North Carolina.
  4. Alfonso, L., J. L. Noguera, D. Babot and J. Estany. 1997. Estimation of genetic parameters for litter size at different parities in pigs. Livest. Prod. Sci. 47:149-156.
  5. Hanenberg, E. H. A. T., E. F. Knol and J. W. M. Merks. 2001. Estimates of genetic parameters for reproduction traits at different parities in Dutch Landrace pigs. Livest. Prod. Sci. 69:179-186.
  6. Rothschild, M. F. and J. P. Bidanel. 1998. Biology and genetics of reproduction. In: The genetics of the pig (Ed. M. F. Rothschild and A. Ruvinsky). CAB International, Oxon, UK. pp. 313-343.
  7. Haley, C. S., E. Avalos and C. Smith. 1988. Selection for litter size in the pig. Anim. Breed. Abstr. 56:317-332.
  8. Liu, W., G. Cao, Z. Zhou and G. Zhang. 2002. Estimation of genetic and phenotypic covariance functions for body weight as longitudinal data of SD-II swine line. Asian-Aust. J. Anim. Sci. 15:622-626.
  9. Logar, B., M. Kovac and S. Malovrh. 1999. Estimation of genetic parameters for litter size in pigs from different genetic groups. Acta Agr. Kapos. 3:135-143.
  10. Crump, R. E., C. S. Haley, R. Thompson and J. Mercer. 1997. Individual animal model estimates of genetic parameters for reproduction traits of Landrace pigs performance tested in a commercial nucleus herd. Anim. Sci. 65:285-290.
  11. Kaplon, M. J., M. F. Rothschild, P. J. Berger and M. Healey. 1991. Population parameter estimates for performance and reproductive traits in Polish Large White nucleus herd. J. Anim. Sci. 69:91-98.
  12. Chen, P., T. J. Baas, J. W. Mabry, K. J. Koehler and J. C. M. Dekkers. 2003. Genetic parameters and trends for litter traits in U.S. Yorkshire, Duroc, Hampshire, and Landrace pigs. J. Anim. Sci. 81:46-53.
  13. Schaeffer, L. R. 2004. Application of random regression models in animal breeding. Livest. Prod. Sci. 86:35-45.
  14. Schaefer, L. R. and J. C. M. Dekkers. 1994. Random regressions in animal models for test-day production in dairy cattle. In: Proceedings of the 5th World Congress on Genetics Applied to Livestock Production, Guelph. 18:443-446.
  15. Oh, S. H., D. H. Lee and M. T. See. 2006. Estimation of genetic parameters for reproductive traits between first and later parities in pig. Asian-Aust. J. Anim. Sci. 19:7-12.
  16. Wang, C. D. and C. Lee. 1999. Estimation of genetic variance and covariance components for litter size and litter weight in Danish Landrace swine using a multivariate mixed model. Asian-Aust. J. Anim. Sci. 12:1015-1018.
  17. Ferraz, J. B. S. and R. K. Johnson. 1993. Animal model estimation of genetic parameters and response to selection for litter size and weight, growth, and backfat in closed seedstock populations of Large White and Landrace swine. J. Anim. Sci. 71:850-858.

Cited by

  1. Multiple-trait structured antedependence model to study the relationship between litter size and birth weight in pigs and rabbits vol.49, pp.1, 2017,
  2. Estimation of genetic parameters for farrowing traits in purebred Landrace and Large White pigs pp.13443941, 2018,
  3. Selecting for changes in average “parity curve” pattern of litter size in Large White pigs vol.136, pp.2, 2018,