Animal Science
- Animal Science / Volume 66 / Issue 03 / June 1998, pp 685-688
- Copyright © British Society of Animal Science 1998
- DOI: http://dx.doi.org/10.1017/S1357729800009255 (About DOI), Published online: 02 September 2010
Research Article
Estimation of genetic parameters for litter size in sheep: a comparison of a repeatability and a multivariate model
M. J. de Vriesa1, E. H. van der Waaija1 and J. A. M. van Arendonka1
a1 Animal Breeding and Genetics Group, Wageningen Institute of Animal Sciences, Wageningen Agricultural University, PO Box 338, 6700 AH Wageningen, The Netherlands
Abstract
Genetic parameters were estimated for litter size in two prolific sheep breeds, i.e. the Zwartbles and the synthetic breed Swifter. Genetic parameters and breeding values for litter size in different parities were estimated using both a repeatability and a multivariate animal model. The estimated heritability from the repeatability model was 0·10 for the Zwartbles and 0·12 for the Swifter. For the multivariate model, heritability of litter size in first, second and third parity was 0·05, 0·07 and 0·10 for the Zwartbles and 0·09, 0·12 and 0·09 for the Swifter. Genetic correlation for litter size in Swifter was 0·81 between parity 1 and 2 and 0·99 between parity 2 and 3. For the Zwartbles genetic correlations were all very close to unity. Environmental correlations between litter size in subsequent parities were not constant over parities. Phenotypic variance in litter size in both breeds was 0·309 in first parity and was almost 50% higher in later parities. Based on the results it is recommended to apply a multiple trait model.
(Received October 09 1997)
(Accepted December 31 1997)
Keywords
- genetic parameters;
- litter size;
- multiple trait;
- repeatability model;
- sheep
