Monitoring of genetic diversity in the endangered Martina Franca donkey population

The Martina Franca (MF) donkey, an ancient native breed of Apulia, was mostly famous for mule production. The breed was at serious risk of extinction in the 1980’s following the drop in demand for draught animals as they were increasingly replaced by agricultural machinery. Much has been done in the last few decades to safeguard the existing donkey breeds, but the situation remains critical. Successful implementation of conservation measures includes an evaluation of the present degree of breed endangerment so the aim of this work was to analyze the demographic and genetic parameters of this breed in order to suggest effective conservation strategies. With a current breed register counting less than 500 recorded animals, the pedigree dataset included 1658 MF donkeys born between 1929 and 2006. Analyses were carried out on the whole dataset as well as on a smaller one consisting of 422 living animals. Demographic and genetic variability parameters were evaluated using the ENDOG (v4.6) software. The pedigree completeness level was evaluated as well as the generation length, which was calculated for each of the four gametic pathways. This information was obtained from animal birth date records together with those of their fathers and mothers. The effective number of founders (fe), the effective number of ancestors (fa), the founder genome (fg), individual inbreeding (F), average relatedness (AR) and the rate of inbreeding (ΔF) per generation were analyzed to describe the genetic variability of the population. Since pedigree depth and completeness were appropriate, especially regarding the current population, the parameters defining genetic variability, namely, fe, fa, fg, F and AR, could be reliably estimated. Analysis of these parameters highlighted the status of endangerment of the MF donkey. Our special concern was with the high percentage of males and females exhibiting elevated AR values. Moreover the effective size of the current population, 48.08, is slightly below the range of the minimum effective size and the rates of inbreeding per generation found in the current MF population exceed the maximum recommended level of 1%. Such a scenario heightens concerns over the endangered status of the MF breed and calls for proper conservation measures and breeding strategies, such as selecting individuals for mating when relationships are below 12.5%.