Technique of direct evaluation of the animal load of a steppe rangeland dominated by Artemisia herba alba in the region of Tebessa (Eastern Algeria)

摘要

The Algerian steppe rangelands are undergoing a degradation of their natural resources, leading to a drastic fall in forage productivity. This fodder production is marked by a great inter-seasonal and inter-annual variability, which makes difficult their management and the calculation of the animal load/hectare during the season. The objective of our study is to develop a direct evaluation technique, simple and quick to implement, to determine the animal load of a steppe rangeland, dominated by the forage plant Artemisia herba alba. For this, we made the hypothesis that there is a fairly strong correlation between the pastoral value (PV) (expressed as a note or score) and the pastoral productivity (PP). Knowing that PP is expressed in FMU/ha/season and calculated from the yield and nutritional value of the plant, we can indirectly deduce an animal load. The disadvantage is that it is an expensive (chemical composition), cumbersome and time-consuming method. These obstacles do not suit the users, especially the time factor closely linked to the stage of exploitation of the plant which evolves rapidly in these areas. On the other hand, the (PV) is a direct evaluation technique less expensive, faster, the result is expressed as a note or a score corresponding to an animal load. The correspondence is established thanks to a set of information such as the global coverage, the specific contribution and the specific index (calculated on the basis of a set of information such as bromatological, appreciation of the stockbreeders, bibliographic...). For our study, the specific index will no longer be empirical and its calculation will be based on the clump volumes of the plant studied. The study proposes a simple management tool to define an opportune period of exploitation of steppe rangelands thanks to the nutritional value of the plant The hypothesis that (PV) and (PP) are strongly correlated was verified (r=0.87), also the hypothesis that dry matter and clump volume are fairly correlated was verified (r=0.74). The results show a pastoral productivity (PP) in the order of 380.38 +/- 12.13 FU/ha and a pastoral value (PV) equal to 11.78 +/- 0.33, which corresponds to a possible load per hectare of the studied range oscillating between 3.13 +/- 0.18 and 3.66 +/- 0.12 sheep units in spring.