142 Utilisation and conservation of farm animal genetic resources
Jörn Bennewitz, Herwin Eding, John Ruane and Henner Simianer
set is formed by breeds that can be considered safe from extinction in the near future. his may encompass breeds that are currently widely used or breeds that already are or
will deinitely be subject to conservation due to special traits, etc.. he diversity is estimated that is conserved by these breeds. hen the breeds not in the safe set are added
one by one with re-placement to the safe set and the increase in conserved diversity of the safe set+1 is estimated. hose breeds that cause the largest increase in conserved
diversity obtain higher priority in the conservation plan. he advantage of this simple approach is that no extinction probabilities need to be speciied; only the breeds for the
safe set have to be chosen. his, however, can also be seen as the biggest disadvantage, since the choice of breeds for conservation is totally independent of the breed’s degree
of endangerment.
6. Is the maximum-utility-strategy efficient for the selection of breeds?
As mentioned in the previous section, the maximum-diversity-strategy is eicient if diversity is the only objective of a conservation plan. If, however, also other features
are included sustainable use in rural areas; chapter 2 in the objective, the maximum- diversity-strategy can be straightforwardly extended to the maximum-utility-strategy,
as it will be shown next. For further details, including applications, the interested reader is referred to Simianer 2002, Simianer
et al. 2003 and Reist-Marti et al. 2006. hese authors also described the use of the optimum allocation scheme Box 6.5
in combination with the utility. he idea of the use of the utility was irst raised by Weitzman 1998.
Let us assume that the objective of a conservation plan includes both the sustainable utilisation and the insurance arguments, the latter including neutral diversity and
special traits paragraph 2. In this case the utility conserved by a set of non-extinct breeds denoted by
K, as in the previous section at a deined future time horizon can be written as Simianer
et al., 2003
K
¦ ¦
i
B i
K j
F K
D K
i j
w k
w D
w U
,
K
K j
K j
j K
i
where U
K
is the utility of the breed set K,
w
D
is the relative value of a unit neutral diversity, D
K
is the neutral diversity of the breed set K;
w
F
j
is the relative value of feature j e.g. a special trait and j∈K denotes for feature j
being present in at least one of the non-extinct breeds, i.e. present in the set K;
• •
• •
also other features included in the conservation objective, e.g. special traits, ixed and variable cost of conservation schemes etc. See Reist-Marti
et al. 2006 for an application.
Utilisation and conservation of farm animal genetic resources 143
Chapter 6. Selection of breeds for conservation
w
B
i
is the relative value of breed i the sustainable utilisation value of the breed;
k
i
is an indicator variable that is equal to 1 if breed i is present in the set K i.e. not extinct or zero otherwise i.e. extinct at the end of the time horizon, depending
on its extinction probability. he irst two terms of the equation shown above address the insurance arguments and
the last term the sustainable utilisation argument. As already stated above, there are 2
N
diferent breed sets K possible, each with a certain probability P
K
. he expected conserved utility at the end of the time horizon
t is
i K
N
P
K
¦
K K
t
U K
P U
E .
i t
i
z U
E mu
w w
Now a marginal utility of a breed can be estimated as mu
i
= -δ EU
t
δ z
i
, which is similar to the estimation of the marginal diversities shown above. Here, a
marginal utility is deined as the change in conserved utility at the end of the deined time horizon when the extinction probability would be lowered by one unit by a
conservation efort. Similarly, a conservation potential of a breed with respect to the utility can be estimated as the product of the marginal utilities and the extinction
probabilities and these can be used to select breeds for conservation.
he second term in the equation shown above, the marginal utility with respect to the special features like e.g. special traits, deserves attention. From a conservation point of
view, it is desirable to maintain such features by conserving at least one breed which has the respective feature. Consequently, the marginal utility of a breed in this context
is heavily dependant on the composition of the set of breeds. For example, if a special trait is present in a number of breeds, of which one is almost perfectly safe, the marginal
utility of the other breeds is low or even zero. If, however, only one breed is let with the desired trait, its marginal utility will be very high, because when it goes extinct, the
special trait will be lost for the whole species.
From a conceptual and systematic point of view, the maximum-utility-strategy seems to be the most favourable method for the selection of breeds. It reduces to the maximum-
diversity-strategy if diversity alone is in the objective of the conservation plan. he problem with this approach is that next to the need for estimates for extinction
probabilities as in the maximum-diversity-strategy additional estimates for the relative economic values of neutral diversity, of the special features e.g. special traits
and for the breed speciic values e.g. the historical value of a breed are needed
w
D
, w
F
j
• •
144 Utilisation and conservation of farm animal genetic resources
Jörn Bennewitz, Herwin Eding, John Ruane and Henner Simianer
and w
F
i
, respectively. At the moment there is no obvious way to obtain these relative weights. he irst attempts have been made by Gandini and Villa 2003 to determine
the cultural values of breeds chapter 2. Deinitely more research is needed to obtain the economic weights for getting the full beneits out of the maximum-utility-approach.
7. What are the practical aspects?
Selection of breeds for conservation is always faced with a substantial amount of uncertainty. We usually have good knowledge about the inventory of breeds and their
