[en] The improvement of pastoral livelihoods in the context of a highly uncertain economic and climatic future implies a double need for conserving livestock biodiversity and reaching productivity gains. In situ conservation through participative genetic improvement programs is a tool of choice for these sustainable development pursuits. In this regard, selection criteria chosen by pastoralist breeders can be classified in two broad categories : productivity-seeking or risk-alleviating. The latter aim was an important motive for the constitution of the present indigenous breeds while the former is often a rationale for their neglect. Understanding the balance can help finding the way to sustainable biodiversity management. As the basis of pastoral livelihood systems, livestock shoulders many roles, among which that of savings may be considered central. Credit facilities lacking in these remote areas, breeders would thus sell part of their productive capital to invest in its improvement. The present model consists in a theoretical inquiry for the possible consequence of this polyvalence of livestock, productive capital and mobilizable saving, on the choice between the two above-mentioned breeding aims under liquidity constraint. A major outcome of the proposed model is the existence of a threshold herd size effect on investment in risk-control. This effect does not bear on investment in productivity and is no longer observed if credit constraint is relaxed. This threshold is thus proposed to entail the presence of an “erosion trap” for biodiversity and further recalls the difficulty to design a breeding program for a group of breeders with very diverse endowments. As a result, appropriate credit programs should be considered as an important key to adoption of breeding schemes for in situ conservation, and thus both their efficiency and viability.