Impacts of food scarcity and irregularities under arid conditions on the body reserves and production of local goat population in the southern of Tunisia

The study aims to study the impact of environmental factors on adult weight and assess the impact of their use from a genetic point of view to set up the basis for the future improvement of this important component of efficient production. A total of 3000 records of 104 goats were collected over a period of 3 years in the caprine herd of the Arid Areas Institute of Médenine (South East of Tunisia). Significance of environmental effects was tested with ANOVA procedure. The adult weight mean estimated in this study was 24.69kg with a coefficient of variation of 24.34%. Local breed was characterized by a low weight. Such a low weight corresponds to low energetic needs, which could be considered as an epigenetic strategy of adaptation to the difficult environmental conditions. Effects reflecting environmental and management conditions along time were highly significant in studied trait. This effect is especially due to the variations of climate, food nutritional quality and herd management along time which change greatly in extensive conditions. Difficult years do not allow the distinction of the best goats, and this is important for breeders who aim to improve the performance of their herds. In order to optimize the productive potential of the local goat population, it is essential to adopt an appropriate feeding management program addressing the most important individual trait which was directly involved in increasing lifetime productivity. The variability detected in local goat population allows to hold expectations for the implementation of selection programmes for productive traits in arid regions.