Eftirfarandi tók ég af heimasíðu EFABIS . Hér eru m.a. skilgreiningar á því hvað telst vera stofn í útrýmingarhættu.
Population structure & inbreeding (F) for the year 2009 Select breeds
Population structure & inbreeding (F) for the year 2009
Breed name:Icelandic goat
Transboundary / brand name:Icelandic goat
Population size - min 585
Population size - max 655
No. of breeding ♀585
No. of breeding ♂70
No. of herds 50
No. of ♀ registered 585
% ♀ being bred pure100
Ne (no selection) 250
Ne (mass selection)175
Estimated ↑ in F per year0.0011
Risk status (FAO - National level) endangered-maintained
Risk status (EAAP - National level) Potentially Endangered
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: Two alternative estimates of effective population size (Ne) are presented in the table. The first, Ne (no selection), 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 (see below). The second method of calculation, Ne (mass selection) originates from the model proposed by Santiago and Caballero (1995, Genetics, vol. 139:1013-1030), that is here implemented in a simplified way as Ne x 0.7. Please note that if index selection is utilized and family information is used to estimate EBVs (such as with BLUP), unless inbreeding restriction strategies are implemented, coefficients smaller than 0.7 should be used. Ne is not shown if insufficient data are available for estimation.
3) Expected inbreeding rate per year: is calculated as (1/(2xNe)) x (1/generation interval), where Ne is the effective population size assuming mass selection. The following species generation intervals are used: horse 4.5 years; cattle 3.5 years; sheep/goat 2.5 years; pigs 1.5 years. 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. A revision of current systems is underway in order to achieve a uniform system across institutions. At this point of time, 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. "Risk status FAO - Global level" is computed considering all breeds with the same transboundary name as one breed.
According to FAO criteria a breed is categorized in one of the following categories:
It is no longer possible to recreate the breed population. This situation becomes absolute when there are no breeding males or breeding females remaining. In reality extinction may be realized well before the loss of the last animal, gamete or embryo.
The total number of breeding females is less than or equal to 100 or the total number of breeding males is less than or equal to five; or The overall population size is less than or equal to 120 and decreasing and the percentage of females being bred to males of the same breed is below 80 percent.
The total number of breeding females is greater than 100 and less than or equal to 1000 or the total number of breeding males is less than or equal to 20 and greater than five; or The overall population size is greater than 80 and less than 1000 and increasing and the percentage of females being bred to males of the same breed is above 80 percent; or The overall population size is greater than 1000 and less than or equal to 1200 decreasing and the percentage of females being bred to males of the same breed is below 80 percent. Breeds may be further categorized as CRITICAL-MAINTAINED or ENDANGERED-MAINTAINED. These categories identify critical or endangered populations for which active conservation programmes are in place or populations are maintained by commercial companies or research institutions.
NOT AT RISK
A breed is categorized as Not at Risk if none of the above definitions apply and: The total number of breeding females and males are greater than 1 000 and 20, respectively; or If the population size is greater than 1 200 and the overall population size is increasing.
The EAAP criteria is based on expected cumulated inbreeding in the next 50 years
and is applicable only to the Cattle, Bufalo, Sheep, Goat, Horse, Ass and Pigs breeds.
A breed is classified as:
Class/Species Cattle/Bufalo Sheep/Goat Horse/Ass Pigs
Critically Endangered Ne<14 Ne<20 Ne<11 Ne<33
Endangered 14<=Ne<20 20<=Ne<28 11<=Ne<16 33<=Ne<47
Minimally Endangered 20<=Ne<32 28<=Ne<45 16<=Ne<25 47<=Ne<74
Potentially Endangered 32<=Ne<67 45<=Ne<95 25<=Ne<52 74<=Ne<157
Not Endangered >=67 >=95 >=52 >=157
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.
Glærur frá nokkrum erindum
Glærur frá nokkurm erindum sem haldin voru á degi geitarinnar 30. nóvember í Þjóðminjasafni Íslands má finna hér
heldur úti heimasíðunni geit.is
Eitt starfandi geitabú á Íslandi
Það er aðeins eitt alvöru geitabú á íslandi og er það Háafell í Hvítársíðu. Bóndinn Jóhanna B. Þorvaldsdóttir mjólkar geiturnar sínar og selur mjólk, kjöt og vörur unnar úr geitamjólk og -mör. Sjáið heimasíðuna hennar geitur.is
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