Trend in inbreeding is the most frequently used method to quantify the rate of genetic drift but, as pointed out by Maignel et al. (1996), it relies on some assumption that could be not fully satisfied in cattle populations. In fact, trend in inbreeding is very sensitive to the quality of the available pedigree information and some beef cattle populations might have a large amount of missing information. An alternative way to quantify the genetic drift is to utilise the method based on probabilities of gene origin (Boichard et al., 1997) with its various measures of genetic contributions of the founders.........
