Improved evaluation of breeding values, modern reproductive technologies and effective selection program have increased inbreeding rates in dairy cattle populations. Several studies describing these changes were summarised by Weigel (2001a). In the USA, Wiggans et al. (1995) reported mean inbreeding coefficients of 0.03 for Holsteins during 1990, and similar estimates for this period were given by Short et al. (1992). Canadian Holstein bulls showed average inbreeding of 2.5% at the same time (Miglior and Burnside, 1995). In the UK Holstein-Friesian population the inbreeding coefficient decreased from 0.74% to 0.38% in 1992 and remained at that level up to 1997. The measures of genetic diversity in this population were not affected by the large importation of North American Friesians (Roughsedge et al., 1999). Introgression of Holsteins has also been taking place in Poland, accelerated in recent years by the modernisation of the dairy industry

W. Jagusiak, A. Zarnecki

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 2002. Session 1, , 1.89, 2002
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