Morphological evolution of Martina Franca donkey

Aim of the research was to describe some morphological traits of Martina Franca donkey breed and their variations over time. The research was carried out on two databases collected in different ways. The first included 41 Martina Franca donkeys (28 females, 13 males), born between 1998 and 2012 in three farms; the animals were measured (wither height: WH, chest circumference: CC, cannon bone circumference: CBC), and the anamorphosis index (AI: CC^2/WH) and the dactylo-thoracic index (DTI: CBC*100/CC) were calculated. The second database included the body measures from 343 adults registered in the herd book (275 females and 68 males), born between 1979 and 2008. The two databases were then combined (384 animals) and two subgroups were isolated: youngs (age <1 year; n=10, 2 females and 8 males) and adults (age >2 years; n=374, 301 females and 73 males). Animals aged between 1 and 2 years were not included. Measures and indexes were submitted to analysis of variance (youngs: fixed effect of sex, random effect of sire and, as a covariate, the age at measurement; adults: fixed effects of sex, year of birth [five classes: <1991, 1991-1995, 1996-2000, 2001-2005, >2005], two-way interaction, random effect of sire and the age at measurement as an intraclass covariate). The results obtained in youngs must be considered as preliminary, due to the reduced number of cases. In young donkeys, sex was never significant (P>0.05), while in adults it was highly significant (P<0.001); this indicates that sexual dimorphism could be evident from the second year of age. In relation to the effect of the year of birth, the results indicate that morphology changed over the years (WH +7.32%; CC +1.19%; CBC +14.90% higher in animals born after 2005 than those born before 1991). Consequently, AI was reduced by 4.63% between donkeys born before 1991 and those born after 2005, confirming an increase in dolicomorphism in the recent population. It can be concluded that the morphology of Martina Franca donkey evolved over the years; the variations can be explained, in part, by the improvement of breeding and feeding, and in part by the change in the genetic evaluation which is no more oriented to produce heavy animals.