SUMMARY
Submitted 2020-06-30 | Accepted 2020-08-09 | Available 2020-12-01https://doi.org/10.15414/afz.2020.23.mi-fpap.74-78Farrowing records of the Duroc, Hampshire and Pietrain breed were analysed by means of a three-trait repeatability animal model. The examined traits were number of piglets born alive (NBA), number of weaned piglets (NWE) and litter weight at weaning (LWWE). Heritability estimates were 0.10, 0.08 and 0.12 for NBA, NWE and LWWE, respectively. The ratios of the permanent environmental variance to the phenotypic variance were 0.08, 0.05 and 0.03 for NBA, NWE and LWWE, respectively. Using the estimated breeding values a desired index was constructed in order to improve each trait by one additive genetic standard deviation. NWE and NBA have a high correlation and range within breeds from 0.87 to 0.91, but LWWE had poor to moderate correlation with NBA and NWE (0.13 to 0.59). Animals ranking based on index showed better genetic merit for Duroc breed and the index scores ranged from 49.77 to 186.56. In the case of Hampshire and Pietrain breeds somewhat lower index scores (30.92 to 165.97) were observed. The estimated genetic trend for NBA was highest for the Pietrain breed (0.02), but for Duroc and Hampshire breeds the estimates were zero and negative (-0.01). For NWE the estimated genetic trends were practically zero for Duroc and Pietrain breeds and it was 0.02 for Pietrain. LWWE showed highest genetic trend for Duroc breed (0.17) but it was lower (0.09) for Pietrain and and negative (-0.24) for Hampshire.Keywords: pig, selection, breeding value, desired gain index, aggregate genotypeReferencesBrascamp E.W. (1984). Selection indices with constraints. Animal Breeding Abstracts 52, 645-654.Groeneveld E, Kovac M, Mielenz N. (2008). VCE User’s guide and reference manual. Version 6.0. Neustadt, Germany: Institute of Farm Genetics; p. 1–125.Groeneveld E. (1990). PEST Users’ manual. Institute of animal husbandry and animal behaviour Neustadt: Federal Research Centre.Hamann, H., Steinheuer, R., & Distl, O. (2004). Estimation of genetic parameters for litter size as a sow and boar trait in German herdbook Landrace and Pietrain swine. Livestock Production Science, 85(2-3), 201-207. https://doi.org/10.1016/s0301-6226(03)00135-0Hungarian Pig Breeders Association (2017). Pig performance testing code. Budapest, 1-39.Chen, P., Baas, T. J., Mabry, J. W., Koehler, K. J., & Dekkers, J. C. M. (2003). Genetic parameters and trends for litter traits in US Yorkshire, Duroc, Hampshire, and Landrace pigs. Journal of animal science, 81(1), 46-53. https://doi.org/10.2527/2003.81146xIrgang, R., Favero, J. A., & Kennedy, B. W. (1994). Genetic parameters for litter size of different parities in Duroc, Landrace, and Large White sows. Journal of Animal Science, 72(9), 2237-2246. https://doi.org/10.2527/1994.7292237xNagy, I. (2017). Quantitative genetic studies in multiparous species. DSc. Thesis. 1-150.Nath, M., Singh, B.P., Kataria, M.C. Singh, R.V. (2002). MIX: A software for construction of multi-trait selection index. In: Proc. of the 7th World’s Congress on Genetics Applied to Livestock Production. August 19–23, 2002, Montpellier, France.Skorupski, M. T., Garrick, D. J., & Blair, H. T. (1996). Estimates of genetic parameters for production and reproduction traits in three breeds of pigs. New Zealand Journal of Agricultural Research, 39(3), 387-395. https://doi.org/10.1080/00288233.1996.9513198