Seasonal variations of chemical composition, intake and digestibility by ewes of natural pasture in the south-eastern regions of Algeria
2009
Chemmam, M. | Ouzrout, R. | Guellati, M.A. | Moujahed, N.
The effect of season on pasture botanical and chemical compositions, herbage biomass, organic matter intake by ewes and nutrient digestibility coefficients were investigated in the region of Sedrata (south-east of Algeria). The botanical composition and the herbage biomass were determined using the transect method in spring (last two weeks of March) and summer (last two weeks of June). Simultaneously, dry matter intake (DMI) and digestibility coefficients of organic matter (OM), crude protein (CP) and neutral detergent fibre (NDF) of pasture herbage were evaluated using 5 Ouled Djellal breed ewes. Acid insoluble ash (AIA) as an internal marker in faeces and in pasture biomass was used to estimate digestibility and therefore intake. The experiment was repeated through two consecutive years (2001-2002). The legume proportion was higher (P less than 0.01) in spring than in summer (21 and 11 per cent of DM respectively). The same trend was observed for grass proportion (67 and 57 per cent respectively). The crude protein content of the herbage decreased (P less than 0.001) from spring to summer (15 and 9.4 per cent of DM respectively). Total cell wall content (NDF) was higher (P less than 0.001) in summer than in spring (62.7 and 53.7 per cent of DM respectively). The DM intake by ewes decreased significantly (P less than 0.001) as the grazing season advanced (1268 and 1085 g DM per day in spring and in summer, respectively). The same trend was observed for OM, CP and NDF digestibility coefficients (P less than 0.001). It was concluded that in the studied region, pasture was of a higher feeding value in spring than in summer
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