Geographic distribution of the Bulgarian Screw-Horn Longhair Goat potential threats to the population diversity

Abstract

The geographic distribution of the breeds has its role in the management and conservation of the animal genetic resources. Geographically concentrated populations are more vulnerable, due to increased risk of loss of animals in case of disaster or disease outbreak. Many systems for estimation of the risk include components to account for the concentration, usually via the minimum enclosing circle centred in the centroid of the farm locations and containing 75% of the breed. In this study, we present an approach to investigate the concentration on sub-population level and its impact on the population size and diversity For each subset of farms, concentrated in a circle with radius 25 km and 50 km, we have calculated the potential loss of animals and estimated the effective population size of the remaining population. Although this method is applicable to breeds present in a small number of farms, it provides insight of potential loss of groups of closely located farms The Bulgarian Screw-Horn Longhair Goat, one of the few local goat breeds, is an example of such breed. In year 2020, 20 flocks with 3107 animals were kept, mainly in two distant regions in North-West and South-West Bulgaria, estimated effective population size of the breed – 346. The application of the method to the Bulgarian Screw-Horn Longhair Goat showed that although the breed is not geographically concentrated on country and regional level, there are some clusters of farms in the two main regions. The distribution of the farms and the animals within the farms present a threat of potential loss of 25% to 58% of the population size and effective population size of the remaining population 40% to 88% of the current one.