Influence of mineral composition and rumen degradability of <i>Atriplex nummularia</i> (Hatfield Select F₁) plants on selection preference of sheep

Abstract

This study examined intraspecific variation in mineral composition and rumen degradability of Atriplex nummularia plants and the influence on selection preferences of sheep. Individual plants  were categorised into high, medium and least preference groups by assessing the order in which they were selected by sheep. Nine plants were selected from each group and the regrowth of these plants was analysed for neutral detergent fibre (NDF), crude protein (CP), mineral composition and rumen degradability of dry  matter. The data was subjected to one-way and multivariate analyses of variance. Highly preferred plants had a higher concentration of CP,  phosphorous (P) and magnesium (Mg) in their edible forage compared to the medium or least preferred plants. Individual preferences of sheep were not, however, associated with the rumen degradability parameters. Principal component analysis revealed that highly preferred plants had lower NDF, manganese (Mn) and zinc (Zn), and higher CP, calcium, P, Mg and potassium values compared to the least preferred plants. In contrast, medium preferred plants exhibited inconsistent patterns, with a tendency to have higher sodium chloride and sodium, and lower Mn, Zn and copper, concentrations in the forage.

African Journal of Range & Forage Science 2009, 26(2): 91–96