1) Population size min & max: In some areas of the world it can be difficult to estimate population size. For this reason, minimum and maximum estimates are used.
2) Ne: The effective population size (Ne) is calculated according to the formula Ne=(4MF/(M+F)) (Wright, S. 1931, Genetics, vol. 16: 97-159), where M and F are respectively the number of breeding males and females. This formula assumes absence of selection and a "limited" variance of the number of progeny among breeding animals - two conditions that generally do not apply to livestock productions. If selection is present, even some mass selection (i.e. on phenotype), the Wright formula overestimates Ne and consequently leads to an underestimation of expected annual inbreeding rates. Ne is not shown if insufficient data are available for estimation.
3) Estimated ↑ in F per year: is calculated as (1/(2xNe)) x (1/generation interval). The following species generation intervals are used: horse/ass 10 years; cattle/buffalo 5 years; sheep/goat 4 years; pigs 2 years (Groeneveld et al. 2009, Leroy et al. 2013). Inbreeding rate is not shown if insufficient data are available to estimate it.
4) Risk status: is currently computed in different ways, depending on criteria and thresholds considered.The table shows risk status following the criteria currently used by FAO and risk status following the criteria used by EAAP. Risk status is blank if insufficient data are available to estimate it.
The EAAP criteria is based on expected cumulated inbreeding in the next 50 years and is applicable only to the Cattle, Buffalo, Sheep, Goat, Horse, Ass and Pigs breeds. A breed is classified as:
In case the number of herds is less than 10 and the number of breeding females is below 500 the breed is assigned to the upper class. In the number of breeding females is below 1000 and decreasing the breed is classified to the upper level. Alternatively, if the number of breeding females is below 1000 and annual growth rate is below 1 the breed is classified to the next higher EAAP endangerment class.