Lamb stocking, grazing system and supplementation effects on Triticale and ryegrass swards performance in Uruguay

An experiment was carried out from 3 of July to 22 of October 1998, using a Lolium multiflorum Lom. (ryegrass) and Triticosecale Wittmack (triticale) sward grazed by lambs, to examine the effect of stocking rate (SR; 25 and 35 lambs/ha), grazing system (GS; strip and 7 days rotational grazing) and supplementation (S; with or without) on sward structure, production, composition and nutritive value. SR affected significantly pre and post grazing herbage mass and sward height, being higher at the lower SR (3211 vs 2832 kg DM ha(-1), P < 0.01; 2443 vs 1939 kg DM ha(-1), P < 0.01; 19 vs 17 cm, P < 0.01 and 10 vs 8 cm, P < 0.01 respectively), increasing, at the high SR, the proportions of the ryegrass green leaf component, particularly in the uppermost layers of the sward canopy. In comparison with 7 days rotational GS, strip GS resulted in higher post grazing herbage mass, sward height and nutritive value (2387 vs 1996 DM ha(-1), P < 0.01; 10 vs 9 cm, P < 0.01; 62 vs 67 % NDF, P < 0.01 and 33 vs 37 % ADF, P < 0.01). S increased post grazing herbage mass and sward height (2347 vs 2035 DM ha(-1), P < 0.01 and 10 vs 9 cm, P < 0.01). This experiment showed the high forage productive potential and nutritive value of ryegrass and triticale swards for lamb production in the sandy soil region of Uruguay and the dominant effect of SR on swards variables comparing with GS and S.