Mineral balance of sheep fed pasture, tagasaste, or tagasaste with a mineral supplement

Abstract

Eighteen young sheep (average weight 34 kg) were fed about 750 g DM/day of green pasture, freshly harvested tagasaste, or tagasaste supplemented with minerals [phosphorus (P), sulfur (S), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na)], for 18 days in metabolism cages. The in vivo digestibility of the pasture was significantly greater than that of the tagasaste (730 v. 674 g/kg); the digestibility of the supplements plus tagasaste (651 g/kg) was similar to that of the tagasaste alone. The daily intake of N, P, S, K, Ca, Mg, and Na was less for sheep on the unsupplemented tagasaste diet than on the pasture diet. Retention of minerals by the sheep was similar on all diets, except that there was greater retention of P and S on the pasture diet. Mineral supplementation did not increase retention of any mineral.