In recent years the widespread use of few genetically superior and outstanding proven sires has caused concern the industry with inbreeding problems. Inbreeding is the mating of animals that are related. It makes pairs of genes alike and thus may reduces genetic diversity of each animal and has harmful effects on production and reproduction traits (Falconer, 1989). The harmful impact of inbreeding on milk production traits has been reported in many studies. Miglior (1994), using records of Canadian Holstein cows, reported that on average the inbreeding depression per each 1% increase in inbreeding is 24.8 kg and 0.9 kg, respectively, for milk and fat yields. For U.S. Holstein cows, estimates were much larger, and were –29.6 kg and –1.1 kg (Wiggans, et al., 1995) and –37.0 kg and –1.0 kg (Cassell, 1999), respectively, for milk and fat yield for each 1% increase in inbreeding. For Iran Holsteins, there is no investigations dealing with inbreeding. The objective of present study was to calculate level of inbreeding and estimate the inbreeding depression on milk and fat yields for Iran Holstein population. 

R. Tohidi, R. V Torshizi, M. M Shahrebabak, M. BS Nejad

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 2002. Session 1, , 1.55, 2002
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