The local goat population in Tunisia is composed of a mosaic of phenotypes and genotypes that remains fundamentally represented by the autochthonous "Arbi" goat breed. The Arbi is more concentrated in the marginal zones, where it is exclusively reared under extensive breeding systems. The Arbi is primarily raised for meat, but milk is also harvested for household use. The Tunisian domestic local goat population displays remarkable adaptation features and the ability to valorize scanty and otherwise unused natural resources. According to the archaeological data, it is believed that the Tunisian local domestic goat derives from the wild Capra aegagrus goat species. The wild type spread to the Mediterranean islands, including the Tunisian Galite Island, and survived amid very low trophic conditions thanks to its high adaptability. The goat was effectively redomesticated in Tunisia by drawing from the wild goat herds on the island and then underwent a wide territorial distribution.

The Tunisian indigenous Arbi goat is also called "Bedouin" or "Moor" goat and it is recognizable by its small size and its dark brown to black coat with long hair. The morphological characteristics are similar to the Berber goat of neighbouring countries, such as a small body size, with a height at the withers from 70 to 76 cm for males and is around 60 cm for females and an average weight of 38 kg for males and 24 kg for females. After its introduction into Tunisia, the Arbi goat population was primarily raised in the southern dry regions of the country. Then the breed experienced a wide evolution that endowed it with an important biological diversity, as demonstrated by the range of different phenotypes and pigmentary types that can be found within the same herd within the same individual. Indeed, the evolutionary history that the Arbi goat has experienced was marked by the casual introduction of and occasional hybridization with six exogenous breeds, namely the Nubian, the Boer, the Maltese, the Murciana, the Alpine and the Damascene breed; which were able to evolve under Tunisian conditions while generating numerous crossbreds. 

The evolution that the Arbi goat underwent in the dry regions has reinforced its genetic merit in terms of adaptation, as this process bestowed to the breed specific superior anatomical and behavioral traits and defined it as a unique and indispensable genetic resource. In fact, the indigenous goat developed effective behavioral and physiological attributes in response to the strong constraints of the dry areas. Indeed, the breed has the particular ability to cover its energy needs and maintain a constant level of intake through various adjustments. It has an affinity for woody plants rather than herbaceous plants and it selects unique species that are less accessible (thorny) but rich in nitrogenous matter and low in crude cellulose, with good digestibility and a higher energy content. This capacity of the Tunisian goat to be highly selective in its consumption is associated with the breed having a superior digestive physiology that enables better urea recycling and digestion of poor-quality forages. Natural selection has allowed the autochthonous goat population to acquire various rusticity features, leading to a continuous evolution for adaptation. The Arbi goat can therefore sustain livelihoods of livestock keepers in environments with low potential for production by other breeds and species or agricultural value chains. 

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Yosra Ressaissi

Photo: Lassad Khlijini and Sarra Chelbi