Mineral composition of the grass grazed by heifers in northeastern Algeria

Abstract

The objective of this study was to provide a more precise understanding of the mineral quality of the grass exploited as pasture by modern breed dairy cows in northeastern Algeria. The study was conducted during two seasons (winter and spring) in four natural prairies located in ecologically distinct areas: El-kala, Lac des oiseaux, El-Aioun, and Bougous.
 During the two consecutive experimental seasons, phytosociological surveys were carried out using the Braun-Blanquet method (1951) to evaluate the floristic composition of each prairie. At each sampling date, forage samples from each prairie were dried in an oven for 48 hours at 60°C, weighed, and ground to determine the mineral composition (Ca, Mg, P, K, and Fe).
 The phytosociological surveys allowed for the identification of a total of 34 plant species, with 13 species in winter and 29 species in spring. However, the contribution of Poaceae and Fabacea was low during both seasons. Furthermore, our observations indicate that the grass during both seasons is deficient in minerals, except for iron. Calcium, magnesium, potassium, and iron levels are higher in spring, but they still remain insufficient to meet the nutritional needs of the heifers. On the other hand, phosphorus values are similar between spring and winter grass (P > 0.01).
 The significant variations in floristic composition between the two seasons, especially concerning legumes, grasses, asters, and other plant families, play a determining role in the observed differences in mineral content between these two periods. These variations in vegetation lead to changes in the available mineral intake from the grass, directly influencing the nutritional quality of the vegetation available to the animals during both seasons.