Demographic studies of the Miranda donkey breed - the challenges to avoid extinction

The endangerment of extinction of most donkeys’ breeds in Europe deems for a better characterization of the genetic diversity of these breeds and understanding the reasons for its declining numbers, biologically and socioeconomically. The main purpose of this study is to predict the viability of the Miranda breed, identify the variables that may be crucial for conservation, and suggest new management strategies. To achieve these aims, pedigree records were analysed and socioeconomic features of herds and owners were typified to identify current environmental and management factors affecting the breeds’ future. The available data showed that, under the current management, this breed faces extinction in the next 50 years. Identified parameters suggested that, keeping all the other variables at the current level, it would be needed to cumulatively:

  1. increase the percentage of females breeding yearly, from 20% to >35%;
  2. to decrease female mortality, from around 20% to 15% for the first year of life and to 2% in the subsequent years until 20 years;
  3. to reduce harvesting to 5 females per year; and
  4. to reduce the age at first offspring in females to 4 years.

The age pyramid of the breed is unbalanced and, without the implementation of an energetic strategy for breeding, in a few years the lack of replacement animals may raise a huge constraint to conservation programs. The analysis showed an important loss of founder genetic diversity, perceived by the low effective number of founders compared to the real number of founders. Less than 55% of the 580 adult females registered in the Studbook ever foaled and the average foaling rate per jenny was only 1.05. This is mainly due to social and demographic changes, which dictated the abandon of donkeys as a rural workforce. Most owners, especially the older ones possessing one or two animals, do not foresee the need to replace their animals in their lifetime and do not want the inconvenience of managing late gestation and raising foals. The relatively long generation intervals observed enhance the importance for a rapid onset of the recovery programs, since it will take time just to replace the current population and even more to rejuvenate it.

Start page
End page