Studies on the supplementary feeding of sheep consuming mulga (Acacia aneura). 3. The provision of phosphorus, molasses and urea supplements under pen conditions

Abstract

Mulga (Acacia aneura) was fed to five groups of four weaner wethers. One group was given a supplement of phosphorus (P) as NaH2PO4, another energy as molasses (E), a third both phosphorus and molasses (P + E) and the fourth urea, phosphorus and molasses (P + E + N) ; the fifth group acted as an unsupplemented control (C). Total dry matter intake during the 42 weeks of the experiment was progressively increased by the addition of P, E, P + E and P + E + N to the diet. Liveweight gain was highest inthe P + E + Ngroup followed by the P + Egroupandthen the E group. Groups P and C lost weight during the experiment. Balance studies showed that P + E and P + E + N supplementation enhanced nitrogen retention, and phosphorus supplementation increased phosphorus retention. The digestibility of mulga was increased by phosphorus supplementation. Specific gravity and phosphorus content per unit volume of bone were increased by supplementation with P + E + N and P + E, and phosphorus content was marginally increased by P supplementation.