Effects of supplementing native pasture hay with puncture vine (Tribulus terrestris) on the intake, weight change, nitrogen balance and excretion of purine derivatives of sheep.

Published Article.,Eight male sheep (average 34.17 ± 3.33 kg LW) were used in a nitrogen balance trial to measure dry matter intake, weight change, nitrogen balance and microbial protein yield. A completely randomized design was used and the animals were randomly allocated to the two treatment diets. The sheep were given a) native pasture hay (NPH) + 100 g crushed maize (CM )(control diet) or b) NPH + 100 g CM + 160 g Tribulus terrestris. The native pasture hay comprised of a mixture of grasses with Heteropogon contortus, Eragrostis rigidiour and E. superba being predominant and had a crude protein content of 37.5 g/kg DM. The puncture vine was harvested at the onset of flowering, dried and graded to remove large stems and woody fruits. The total feed intake (918.14 g/d) of sheep given T. terrestris supplement was significantly (P< 0.05) higher than that of the control diet (553.70 g/d). T. terrestris supplementation also resulted in an average weight gain of 38.13 g/d while on the control diet an average loss of 130.43 g/d was recorded. Puncture vine supplementation also resulted in higher nitrogen retention (2.30 g/d) as compared to the control diet (0.43 g/d). Microbial protein yield was 16.48 g/d with puncture vine supplementation and 6.39 g/d for the control diet. The results show that the inclusion of T. terrestris as a protein supplement to low quality natural pasture hay diets increases dry matter intake, nitrogen balance and microbial protein yield